Technology of cereals and pulses Class notes
mohitjindal
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About This Presentation
Technology of cereals and pulses Class notes
Slide Content
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 1 of 162
Some important crops globally.
India- Targets and Achievements of Production of major crops during 2002-03 to
2006-07 (Million Tonnes)
Crop 2002-03 2003-04 2004-05 2005-06 2006-07
(Kharif only)
Serial
No.
Common Name Vernacular
Name
Botanical Name
1 Wheat Gehun Triticum spp.
2 Maize or Corn Makka Zea mays
3 Rice Chaval Oryzae sativa
4 Oats Jai Avena spp.
5 Barley Jau Hordeum vulgare
6 Sorghum Jowar Sorghum vulgare or S. bicolor
7 Pearl Millet Bajra Pennisetum typhoideum or P. Americana
8 Finger Millet Ragi Eleusine coracana
9 Kodo Millet Pakodi Arika Paspalum scrobiculatum
10 Proso Millet Vari or Kutki Panicum miliaceum
11 Little Millet Panicum miliare
12 Foxtail Millet Rala or KangniSetaria italica
13 Japenese Barnyard Millet Echinochloa colona
14 Gram or Chick Pea Chana Cicer arietinum
15 Peas Mattar Pisum sativum
16 Pigeon Pea Arhar Cajanus spp.
17 Lentil Masur Lens culinaris or L. esculenta
18 Mung Bean Mung Phaseolus aureus
19 Urd Bean or Black GramUrd Phaseolus mungo
20 Moth Bean Moth Phaseolus aconitifolius
21 Soybean Bhatt or Japan PeaGlycine max
22 Lablab Sem Dolichos lablab
23 Groundnut or Peanut Moongphali Arachis hypogaea
e-- [email protected] Page 1 of 162
Some important crops globally.
India- Targets and Achievements of Production of major crops during 2002-03 to
2006-07 (Million Tonnes)
Crop 2002-03 2003-04 2004-05 2005-06 2006-07
(Kharif only)
Serial
No.
Common Name Vernacular
Name
Botanical Name
1 Wheat Gehun Triticum spp.
2 Maize or Corn Makka Zea mays
3 Rice Chaval Oryzae sativa
4 Oats Jai Avena spp.
5 Barley Jau Hordeum vulgare
6 Sorghum Jowar Sorghum vulgare or S. bicolor
7 Pearl Millet Bajra Pennisetum typhoideum or P. Americana
8 Finger Millet Ragi Eleusine coracana
9 Kodo Millet Pakodi Arika Paspalum scrobiculatum
10 Proso Millet Vari or Kutki Panicum miliaceum
11 Little Millet Panicum miliare
12 Foxtail Millet Rala or KangniSetaria italica
13 Japenese Barnyard Millet Echinochloa colona
14 Gram or Chick Pea Chana Cicer arietinum
15 Peas Mattar Pisum sativum
16 Pigeon Pea Arhar Cajanus spp.
17 Lentil Masur Lens culinaris or L. esculenta
18 Mung Bean Mung Phaseolus aureus
19 Urd Bean or Black GramUrd Phaseolus mungo
20 Moth Bean Moth Phaseolus aconitifolius
21 Soybean Bhatt or Japan PeaGlycine max
22 Lablab Sem Dolichos lablab
23 Groundnut or Peanut Moongphali Arachis hypogaea
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 2 of 162
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Rice 93 71.82 93.00 88.53 93.50 83.13 87.80 91.04 80.78 75.74
Wheat78 65.76 78.00 72.15 79.50 68.64 75.53 69.48 - -
Coarse
Cereal
s
33 26.07 34.00 37.60 36.80 33.46 36.52 34.67 28.69 24.51
Pulses 16 11.13 15.00 14.91 15.30 13.13 15.15 13.11 5.78 4.97
Food
Grains
220174.7
7
220.0
0
213.1
9
225.1
0
198.3
6
215.0
0
208.3
0
115.2
5
105.2
2
Oil
Seeds
27 14.8424.7025.1926.2024.3526.5827.7318.1213.24
# Million Bales of 170 kg. each.
@ Million Bales of 180 kg. each.
Advance Estimates as on 15.07.2006
$ Advance Estimates as on 15.09.2006
4.2: Three Largest Producing States of Important Crops during 2005-06
Production : Million Tonnes
Crop/ Group of Crops States Production
I. Foodgrains
Rice West Bengal 14.51
Andhra Pradesh 11.70
Uttar Pradesh 11.13
Wheat Uttar Pradesh 24.07
Punjab 14.49
Haryana 8.86
Maize Andhra Pradesh 3.09
Karnataka 2.73
Bihar 1.36
Total Coarse Cereals Karnataka 6.56
Maharashtra 6.09
Rajasthan 4.53
Total Pulses Madhya Pradesh 3.23
Uttar Pradesh 2.23
Maharashtra 2.01
Total Foodgrains Uttar Pradesh 40.41
Punjab 25.18
Andhra Pradesh 16.95
II .Oilseeds
Groundnut Gujarat 3.39
Andhra Pradesh 1.37
e-- [email protected] Page 2 of 162
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Rice 93 71.82 93.00 88.53 93.50 83.13 87.80 91.04 80.78 75.74
Wheat78 65.76 78.00 72.15 79.50 68.64 75.53 69.48 - -
Coarse
Cereal
s
33 26.07 34.00 37.60 36.80 33.46 36.52 34.67 28.69 24.51
Pulses 16 11.13 15.00 14.91 15.30 13.13 15.15 13.11 5.78 4.97
Food
Grains
220174.7
7
220.0
0
213.1
9
225.1
0
198.3
6
215.0
0
208.3
0
115.2
5
105.2
2
Oil
Seeds
27 14.8424.7025.1926.2024.3526.5827.7318.1213.24
# Million Bales of 170 kg. each.
@ Million Bales of 180 kg. each.
Advance Estimates as on 15.07.2006
$ Advance Estimates as on 15.09.2006
4.2: Three Largest Producing States of Important Crops during 2005-06
Production : Million Tonnes
Crop/ Group of Crops States Production
I. Foodgrains
Rice West Bengal 14.51
Andhra Pradesh 11.70
Uttar Pradesh 11.13
Wheat Uttar Pradesh 24.07
Punjab 14.49
Haryana 8.86
Maize Andhra Pradesh 3.09
Karnataka 2.73
Bihar 1.36
Total Coarse Cereals Karnataka 6.56
Maharashtra 6.09
Rajasthan 4.53
Total Pulses Madhya Pradesh 3.23
Uttar Pradesh 2.23
Maharashtra 2.01
Total Foodgrains Uttar Pradesh 40.41
Punjab 25.18
Andhra Pradesh 16.95
II .Oilseeds
Groundnut Gujarat 3.39
Andhra Pradesh 1.37
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 3 of 162
Tamil Nadu 1.10
Rapeseed & Mustard Rajasthan 4.42
Uttar Pradesh 0.91
Madhya Pradesh 0.85
Soyabean Madhya Pradesh 4.50
Maharashtra 2.53
Rajasthan 0.86
Sunflower Karnataka 0.79
Andhra Pradesh 0.30
Maharashtra 0.21
Total Oilseeds Rajasthan 5.96
Madhya Prd. 5.72
Gujarat 4.68
World Crop Production Summary: 2001 to 2006
[In millions of metric tons, (581.08 represents
581,080,000), except as indicated]
Commodity World \1 Asia
Selected
Other
Million metric tons RussiaChina IndiaPakistanAustralia
Wheat:
2004-2005 628.7745.4091.9572.06 19.50 22.60
2005-2006 preliminary 621.8647.7097.4572.00 21.50 24.50
Coarse Grains:
2004-2005 1,014.6229.60138.2534.15 1.98 11.57
2005-2006 preliminary 973.4827.60147.4733.67 1.98 13.96
Rice (Milled):
2004-2005 400.49 0.31125.3683.13 4.92 0.23
2005-2006 preliminary 413.11 0.38126.4089.88 5.50 0.72
Total Grains \3:
2004-2005 2,043.8775.31355.57189.34 26.40 34.40
2005-2006 preliminary 2,008.4575.68371.32195.55 28.98 39.17
Oilseeds \4:
2004-2005 381.17 5.6357.9728.64 5.53 2.57
2005-2006 preliminary 390.13 7.4456.5629.82 5.01 2.44
INTERNET LINK
http://www.fas.usda.gov/wap_arc.asp
TOP WHEAT PRODUCING NATIONS - 1996-2002
updated 2/03 with 1/30/03 International Grains Council
"Grain Market Report" figures
Million Tons
Country **2002*2001
China 89.094.0
e-- [email protected] Page 3 of 162
Tamil Nadu 1.10
Rapeseed & Mustard Rajasthan 4.42
Uttar Pradesh 0.91
Madhya Pradesh 0.85
Soyabean Madhya Pradesh 4.50
Maharashtra 2.53
Rajasthan 0.86
Sunflower Karnataka 0.79
Andhra Pradesh 0.30
Maharashtra 0.21
Total Oilseeds Rajasthan 5.96
Madhya Prd. 5.72
Gujarat 4.68
World Crop Production Summary: 2001 to 2006
[In millions of metric tons, (581.08 represents
581,080,000), except as indicated]
Commodity World \1 Asia
Selected
Other
Million metric tons RussiaChina IndiaPakistanAustralia
Wheat:
2004-2005 628.7745.4091.9572.06 19.50 22.60
2005-2006 preliminary 621.8647.7097.4572.00 21.50 24.50
Coarse Grains:
2004-2005 1,014.6229.60138.2534.15 1.98 11.57
2005-2006 preliminary 973.4827.60147.4733.67 1.98 13.96
Rice (Milled):
2004-2005 400.49 0.31125.3683.13 4.92 0.23
2005-2006 preliminary 413.11 0.38126.4089.88 5.50 0.72
Total Grains \3:
2004-2005 2,043.8775.31355.57189.34 26.40 34.40
2005-2006 preliminary 2,008.4575.68371.32195.55 28.98 39.17
Oilseeds \4:
2004-2005 381.17 5.6357.9728.64 5.53 2.57
2005-2006 preliminary 390.13 7.4456.5629.82 5.01 2.44
INTERNET LINK
http://www.fas.usda.gov/wap_arc.asp
TOP WHEAT PRODUCING NATIONS - 1996-2002
updated 2/03 with 1/30/03 International Grains Council
"Grain Market Report" figures
Million Tons
Country **2002*2001
China 89.094.0
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 4 of 162
India 71.568.8
United States44.053.3
France 39.031.4
Russia 50.646.9
TOP RICE PRODUCING NATIONS
China, India, Indonesia, and Bangladesh account for nearly 70 percent of global rice production. China
produces both indica (mostly in the south) and japonica (mostly in the north). India, Indonesia, and
Bangladesh grow primarily indica rice. In addition to China, the other major producers of japonica are:
Japan, South Korea, North Korea, Taiwan, the European Union, Australia, Egypt, and the United
States. Other major producers of indica rice are Thailand and Vietnam.
TOP BARLEY PRODUCING NATIONS
Serial
No. Barley Production 2003
Metric
Ton
1Russian Federation 17,967,900
2Canada 12,327,600
3Germany 10,665,700
4France 9,818,000
5Spain 8,698,400
source: FAOSTAT data, 2004.
TOP MAIZE PRODUCING NATIONS
The top five producers of maize are the
US 229 million MT,
China 124 m MT,
Brazil 35.5 m MT,
Mexico 19 m MT and
France 16 m MT.
e-- [email protected] Page 4 of 162
India 71.568.8
United States44.053.3
France 39.031.4
Russia 50.646.9
TOP RICE PRODUCING NATIONS
China, India, Indonesia, and Bangladesh account for nearly 70 percent of global rice production. China
produces both indica (mostly in the south) and japonica (mostly in the north). India, Indonesia, and
Bangladesh grow primarily indica rice. In addition to China, the other major producers of japonica are:
Japan, South Korea, North Korea, Taiwan, the European Union, Australia, Egypt, and the United
States. Other major producers of indica rice are Thailand and Vietnam.
TOP BARLEY PRODUCING NATIONS
Serial
No. Barley Production 2003
Metric
Ton
1Russian Federation 17,967,900
2Canada 12,327,600
3Germany 10,665,700
4France 9,818,000
5Spain 8,698,400
source: FAOSTAT data, 2004.
TOP MAIZE PRODUCING NATIONS
The top five producers of maize are the
US 229 million MT,
China 124 m MT,
Brazil 35.5 m MT,
Mexico 19 m MT and
France 16 m MT.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 5 of 162
WHEAT
e-- [email protected] Page 5 of 162
WHEAT
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 6 of 162
•1/5 of all calories consumed by humans
•30% of world grain production
•50% of world grain trade
Main wheat exporters- US, Canada, Australia, Argentina, France
Main parts-Germ, Endosperm, Bran
Germ (Embryo)- Germination of wheat seed, all nutrients are present
Endosperm- Store house of wheat, storage as starch mainly
Bran- Outermost covering layer
Some High Yielding Wheat Varieties
1. Sonalika (HD-1553) released in 1967. This is an early maturing variety. It is single gene
dwarf wheat with attractive grains, resembling good quality desi wheats. It is suitable for
timely as well as late sowings in U.P., Haryana, Delhi, Rajasthan, M.P., Maharashtra, A.P.,
Tamil Nadu and Karnataka.
2. Kalyan Sona (HD-1 593) released in 1967. it is a medium late maturing variety. It is high
yielding wheat with widest adaptability. It has been grown in Jammu and Kashmir, Punjab,
Haryana, Delhi, U.P., Rajasthan, M.P., Bihar, Orissa, West Bengal and Maharashtra.
3. Sharbati Sonora released in 1967. Sharbati Sonora is an amber mutant of Sonora-64 with
early maturity and synchronous habit of filleting. It is grown in all wheat growing regions.
4. Shera (HD-1925) released in 1974. It is double dwarf wheat with very good bold amber
grains. It ;s resistant to lodging, shattering and black rust in Central and Western zones of
our country.
5. Rai-911 released in 1974. It is a 2-gene dwarf durum. It is high yielding as well as resistant
to rust. It is suitable for the central wheat tract.
6. Malvika (HD-1502). It is a triple dwarf durum. It is suited for peninsular wheat tract.
7. WL 71 1, UP 368 and HD 2177 are recommended for cultivation under timely sown
irrigated high fertility condition of Punjab, Jammu area, Haryana, Delhi, Western Uttar
Pradesh and Rajasthan (except Kota and Udaipur divisions). These varieties are better than
Kalyan Sona and Sonalika in yield and rust- resistance.
8. WL 410 and C 306 are good for cultivation under low fertility rain-fed conditions of north-
western India.
9. UP 115 and HP 1209 are good for irrigated high fertility and late sowing conditions of
Bihar, eastern Uttar Pradesh, West Bengal, Assam, Orissa and other eastern states.
10. High yielding and disease resistant CC 464 and HD 2189 are good for -peninsular India
comprising Maharashtra, Karnataka, Andhra Pradesh and the plains of Tamil Nadu.
11. HD (Hybrid Delhi)-2204. It is for the first time that a variety of g wheat combines high
yield and disease resistance. It has been recommended for Large-scale cultivation under
high fertility irrigated conditions in the north-western plain zone comprising the country's
wheat bowl areas of Punjab, Haryana, Rajasthan, Uttar Pradesh, Delhi and Jammu and-
Kashmir.
12. IWP-72. It has been recommended for the above-mentioned zone of HD-2204 for rain-
fed cultivation.
13. HW-657. This highly disease-resistant variety has been recommended for filn-fed
cultivation in the peninsular zone states of Maharashtra, Karnataka and Andhra Pradesh.
14. X-7410 and HUW-12. These two varieties have been re- commended for irrigated areas
in the north-eastern plains.
15. VL-421 (Vivekanand Laboratory, Almora). This variety has been recommended for the
north hill zone.
16. The Punjab Agricultural University released a new variety of wheat called WL-71 1.
A brief account of some of the high yielding varieties of wheat is given below.
e-- [email protected] Page 6 of 162
•1/5 of all calories consumed by humans
•30% of world grain production
•50% of world grain trade
Main wheat exporters- US, Canada, Australia, Argentina, France
Main parts-Germ, Endosperm, Bran
Germ (Embryo)- Germination of wheat seed, all nutrients are present
Endosperm- Store house of wheat, storage as starch mainly
Bran- Outermost covering layer
Some High Yielding Wheat Varieties
1. Sonalika (HD-1553) released in 1967. This is an early maturing variety. It is single gene
dwarf wheat with attractive grains, resembling good quality desi wheats. It is suitable for
timely as well as late sowings in U.P., Haryana, Delhi, Rajasthan, M.P., Maharashtra, A.P.,
Tamil Nadu and Karnataka.
2. Kalyan Sona (HD-1 593) released in 1967. it is a medium late maturing variety. It is high
yielding wheat with widest adaptability. It has been grown in Jammu and Kashmir, Punjab,
Haryana, Delhi, U.P., Rajasthan, M.P., Bihar, Orissa, West Bengal and Maharashtra.
3. Sharbati Sonora released in 1967. Sharbati Sonora is an amber mutant of Sonora-64 with
early maturity and synchronous habit of filleting. It is grown in all wheat growing regions.
4. Shera (HD-1925) released in 1974. It is double dwarf wheat with very good bold amber
grains. It ;s resistant to lodging, shattering and black rust in Central and Western zones of
our country.
5. Rai-911 released in 1974. It is a 2-gene dwarf durum. It is high yielding as well as resistant
to rust. It is suitable for the central wheat tract.
6. Malvika (HD-1502). It is a triple dwarf durum. It is suited for peninsular wheat tract.
7. WL 71 1, UP 368 and HD 2177 are recommended for cultivation under timely sown
irrigated high fertility condition of Punjab, Jammu area, Haryana, Delhi, Western Uttar
Pradesh and Rajasthan (except Kota and Udaipur divisions). These varieties are better than
Kalyan Sona and Sonalika in yield and rust- resistance.
8. WL 410 and C 306 are good for cultivation under low fertility rain-fed conditions of north-
western India.
9. UP 115 and HP 1209 are good for irrigated high fertility and late sowing conditions of
Bihar, eastern Uttar Pradesh, West Bengal, Assam, Orissa and other eastern states.
10. High yielding and disease resistant CC 464 and HD 2189 are good for -peninsular India
comprising Maharashtra, Karnataka, Andhra Pradesh and the plains of Tamil Nadu.
11. HD (Hybrid Delhi)-2204. It is for the first time that a variety of g wheat combines high
yield and disease resistance. It has been recommended for Large-scale cultivation under
high fertility irrigated conditions in the north-western plain zone comprising the country's
wheat bowl areas of Punjab, Haryana, Rajasthan, Uttar Pradesh, Delhi and Jammu and-
Kashmir.
12. IWP-72. It has been recommended for the above-mentioned zone of HD-2204 for rain-
fed cultivation.
13. HW-657. This highly disease-resistant variety has been recommended for filn-fed
cultivation in the peninsular zone states of Maharashtra, Karnataka and Andhra Pradesh.
14. X-7410 and HUW-12. These two varieties have been re- commended for irrigated areas
in the north-eastern plains.
15. VL-421 (Vivekanand Laboratory, Almora). This variety has been recommended for the
north hill zone.
16. The Punjab Agricultural University released a new variety of wheat called WL-71 1.
A brief account of some of the high yielding varieties of wheat is given below.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 7 of 162
Variety Description Areas of adaptability
Kalyan Sona A double dwarf variety
released jointly by IARI and
the Punjab Agricultural
University. Most widely
grown in India presently.
Suitable for cultivation under
both normal and late
plantings as well as high
and low fertility conditions,
and irrigated and rain fed
areas. Yields range from 60-
70 quintals/ ha. Grains are
amber, medium and
lustrous. Highly resistant to
loose smut and hill bunt
diseases.
Suitable for cultivation
throughout India.
Sonalika A single dwarf variety next in
popularity to Kalyan Sona in
India. Grains are bold, hard,
lustrous and very attractive.
Sonalika is highly field
resistant to black and brown
rusts. It is suitable for
cultivation under both
normal and late plantings
but particularly suitable for
the later category of
conditions. Yield potential
from 50-65 quintals/ ha.
Suitable for cultivation
throughout India.
Sharbati Sonora An amber grained double
dwarf variety through
irradiation of the red seeded
Sonora-64. It has high
resistance to black rust.
Grains are amber, hard,
lustrous and of medium size.
Protein content high (up to
16%) One of the best
wheats today in India for
bread-making purposes.
Yield potential 50-65
quintals/ ha
Late planting in produced
Punjab, U.P., Rajasthan,
and normal plantings , in
M.P., Bihar, W. Bengal,
Gujarat, Maharashtra, A Pt.,
and Tamil Nadu
The dorsal side of the wheat grain is rounded, and the ventral side has a deep groove or
crease along the entire longitudinal axis. At the apex or small end (stigmatic end) of the grain
is a cluster of short, fine hairs known as brush hairs. The pericarp, or (try fruit coat, consists
of' four layers: epidermis, hypodermis, cross cells, and tube cells. The remaining tissues
of the grain are the inner bran (seed coat and nucellar tissue), endosperm, and embryo
(germ). The aleurone layer consists of' large, rectangular, heavy-walled, starch - free cells.
Botanically, the aleurone is the outer layer of the endosperm, but as it tends to remain
attached to the outer coats during wheat milling.
e-- [email protected] Page 7 of 162
Variety Description Areas of adaptability
Kalyan Sona A double dwarf variety
released jointly by IARI and
the Punjab Agricultural
University. Most widely
grown in India presently.
Suitable for cultivation under
both normal and late
plantings as well as high
and low fertility conditions,
and irrigated and rain fed
areas. Yields range from 60-
70 quintals/ ha. Grains are
amber, medium and
lustrous. Highly resistant to
loose smut and hill bunt
diseases.
Suitable for cultivation
throughout India.
Sonalika A single dwarf variety next in
popularity to Kalyan Sona in
India. Grains are bold, hard,
lustrous and very attractive.
Sonalika is highly field
resistant to black and brown
rusts. It is suitable for
cultivation under both
normal and late plantings
but particularly suitable for
the later category of
conditions. Yield potential
from 50-65 quintals/ ha.
Suitable for cultivation
throughout India.
Sharbati Sonora An amber grained double
dwarf variety through
irradiation of the red seeded
Sonora-64. It has high
resistance to black rust.
Grains are amber, hard,
lustrous and of medium size.
Protein content high (up to
16%) One of the best
wheats today in India for
bread-making purposes.
Yield potential 50-65
quintals/ ha
Late planting in produced
Punjab, U.P., Rajasthan,
and normal plantings , in
M.P., Bihar, W. Bengal,
Gujarat, Maharashtra, A Pt.,
and Tamil Nadu
The dorsal side of the wheat grain is rounded, and the ventral side has a deep groove or
crease along the entire longitudinal axis. At the apex or small end (stigmatic end) of the grain
is a cluster of short, fine hairs known as brush hairs. The pericarp, or (try fruit coat, consists
of' four layers: epidermis, hypodermis, cross cells, and tube cells. The remaining tissues
of the grain are the inner bran (seed coat and nucellar tissue), endosperm, and embryo
(germ). The aleurone layer consists of' large, rectangular, heavy-walled, starch - free cells.
Botanically, the aleurone is the outer layer of the endosperm, but as it tends to remain
attached to the outer coats during wheat milling.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 8 of 162
The embryo (germ) consists of the plumule and radicle, which are connected by the
mesocotyl. The scutellum serves as an organ for food storage. The outer layer of the
scutellum, the epithelium, may function as either a secretary or an absorption organ. In a
well-filled wheat kernel, the germ comprises 2-3% of the kernel, the bran 13-17%, and the
endosperm the remainder. The inner bran layers (the aleurone) are high in protein, whereas
the outer bran (pericarp, seed coats, and nucellus)-is high in cellulose, hemicelluloses, and
minerals; biologically, the outer bran functions as a protective coating and remains practically
intact when the seed germinates. The germ is high in proteins, lipids, sugars, and minerals;
the endosperm consists of largely of starch granules embedded in a protein matrix.
Some Implications of Kernel Structure
Significance Parameter Effect Commodity
Threshing Germ Damage or
Skinning
Reduced Germinability,
Impaired Storability
All Cereal Grains
Drying Cracks, Fissures and
Breakage: Hardening
Reduced Commercial
Value; Lowered Grade,
Impaired Storability, Dust
Formation, Reduced
Starch Yield
Mainly Corn and Rice
Discoloration Reduced Commercial
Value, Lowered Grade
Mainly Rice
Marketing Breakage Reduced Commercial
Value in Food
Processing
Mainly Corn and Rice
General Use High Husk: Caryopsis
Ratio or High
Pericarp: Endosperm
Ratio
Reduced Nutritional
Value as Food and Feed
All Cereal Grains
General Use Kernel Shape and
Dimensions;
Proportion of Tissues
in the Kernel;
Distribution of
Nutrients in the
Tissues
Yield of Food Products;
Nutritional Value of
Cereal (or Cereal
Products) as Food or
Feed
All Cereal Grains
Malting Germ Damage,
Skinning, or
Inadequate Husk
Adherence
Reduced Germinability,
Uneven Malting
Mainly Barley
Milling Uneven Surface,
Deep Crease, or
Uneven Aleurone
Reduced Milling YieldMainly Wheat and
Rice
Milling Steely Texture Increased Power
Requirements, Starch
Damage, High Water
Absorption, Difficulty in
Air Classification
Wheat and Malt
Milling
Germination-
Malting
Starch Granule SizeUneven Degradation All Cereal Grains
Consumption-
Nutrition
Distribution and
Composition of
Proteins
Change in Nutritional
Value
All Cereal Grains
e-- [email protected] Page 8 of 162
The embryo (germ) consists of the plumule and radicle, which are connected by the
mesocotyl. The scutellum serves as an organ for food storage. The outer layer of the
scutellum, the epithelium, may function as either a secretary or an absorption organ. In a
well-filled wheat kernel, the germ comprises 2-3% of the kernel, the bran 13-17%, and the
endosperm the remainder. The inner bran layers (the aleurone) are high in protein, whereas
the outer bran (pericarp, seed coats, and nucellus)-is high in cellulose, hemicelluloses, and
minerals; biologically, the outer bran functions as a protective coating and remains practically
intact when the seed germinates. The germ is high in proteins, lipids, sugars, and minerals;
the endosperm consists of largely of starch granules embedded in a protein matrix.
Some Implications of Kernel Structure
Significance Parameter Effect Commodity
Threshing Germ Damage or
Skinning
Reduced Germinability,
Impaired Storability
All Cereal Grains
Drying Cracks, Fissures and
Breakage: Hardening
Reduced Commercial
Value; Lowered Grade,
Impaired Storability, Dust
Formation, Reduced
Starch Yield
Mainly Corn and Rice
Discoloration Reduced Commercial
Value, Lowered Grade
Mainly Rice
Marketing Breakage Reduced Commercial
Value in Food
Processing
Mainly Corn and Rice
General Use High Husk: Caryopsis
Ratio or High
Pericarp: Endosperm
Ratio
Reduced Nutritional
Value as Food and Feed
All Cereal Grains
General Use Kernel Shape and
Dimensions;
Proportion of Tissues
in the Kernel;
Distribution of
Nutrients in the
Tissues
Yield of Food Products;
Nutritional Value of
Cereal (or Cereal
Products) as Food or
Feed
All Cereal Grains
Malting Germ Damage,
Skinning, or
Inadequate Husk
Adherence
Reduced Germinability,
Uneven Malting
Mainly Barley
Milling Uneven Surface,
Deep Crease, or
Uneven Aleurone
Reduced Milling YieldMainly Wheat and
Rice
Milling Steely Texture Increased Power
Requirements, Starch
Damage, High Water
Absorption, Difficulty in
Air Classification
Wheat and Malt
Milling
Germination-
Malting
Starch Granule SizeUneven Degradation All Cereal Grains
Consumption-
Nutrition
Distribution and
Composition of
Proteins
Change in Nutritional
Value
All Cereal Grains
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 9 of 162
THE HULL AND BRAN LAYERS
The outer pericarp layers of' wheat (epidermis and hypodermis) have no intercellular spaces
and are closely adhering thick walled cells. The inner layers of the pericarp, on the other
hand, consist of thinned walled cells and often contain intercellular spaces, through which
water can move rapidly and in which molds are commonly found. Molds can also enter
through the large intercellular spaces at the base, of the kernel where the grain was
detached from the plant at harvest and where there is no protective epidermis. The structure
of the pericarp, seed coats, and nucellus also explains how the kernel reacts to water.
Following initial rapid water absorption, the rate decreases significantly. The seed coat offers
more water resistance than the nucellus. The ability of the germ to absorb and hold
considerable amounts of water probably accounts in part for the susceptibility of the germ to
attack by molds.
An intact grain stores much better than damaged or ground grain. Deteriorative changes (i.e.,
rancidity, off-flavors, etc) occur slowly in the whole grain but rapidly after the grain has been
ground. The hull, apparently, prevents the grain from becoming rancid by protecting tile bran
layers from mechanical damage during harvesting and subsequent handling.
THE GERM
The germ is a separate structure that generally can be easily separated from the rest of the
cereal grain. However, the scutellar epithelium (located next to the endosperm) has finger
like cells. The free ends protrude toward the adjacent starch endosperm cells and form all
amorphous cementing layers between the germ and endosperm. If part of the layer projects
into the spaces between the fingerlike cells of the scutellar epithelium and into the folds of
the scutellar structure, it may be difficult to separate the germ from the endosperm unless the
cementing layer is softened. The softening may be accomplished by steeping in corn wet
milling or by conditioning in wheat milling. In rice, a layer of crushed cells separating the
scutellar epithelium from the starchy endosperm provides a line of easy fracture.
Germ separation is also enhanced by the fact that the germ takes up water faster and swells
more readily than the endosperm. The strains resulting from differential swelling contribute to
easy separation in milling.
COMPOSITION
Like that of other foods of plant origin, the chemical composition of the dry matter of different
cereal grains varies widely. Variations are encountered in the relative amounts of proteins,
lipids, carbohydrates, pigments, vitamins, and ash; mineral elements present also vary
widely. As a food group, cereals-are characterized by relatively low protein and high
carbohydrate contents; the carbohydrates consist, essentially of starch (90% or more),
dextrins, pentosans, and sugars.
Table 4-2 Weight, Ash, Protein, Lipid and Crude Fiber Contents of main anatomical
parts of the wheat kernel and flours of different milling extraction rates.
Parameter
(%)
Wheat Kernel Fractions Milling Extraction (%)
PericarpAleurone
Layer
Starchy
Endosperm
Germ
Weight 9 8 80 3 75 83 100
Ash 3 16 0.5 5 0.5 1 1.5
Protein 5 18 10 26 11 12 12
e-- [email protected] Page 9 of 162
THE HULL AND BRAN LAYERS
The outer pericarp layers of' wheat (epidermis and hypodermis) have no intercellular spaces
and are closely adhering thick walled cells. The inner layers of the pericarp, on the other
hand, consist of thinned walled cells and often contain intercellular spaces, through which
water can move rapidly and in which molds are commonly found. Molds can also enter
through the large intercellular spaces at the base, of the kernel where the grain was
detached from the plant at harvest and where there is no protective epidermis. The structure
of the pericarp, seed coats, and nucellus also explains how the kernel reacts to water.
Following initial rapid water absorption, the rate decreases significantly. The seed coat offers
more water resistance than the nucellus. The ability of the germ to absorb and hold
considerable amounts of water probably accounts in part for the susceptibility of the germ to
attack by molds.
An intact grain stores much better than damaged or ground grain. Deteriorative changes (i.e.,
rancidity, off-flavors, etc) occur slowly in the whole grain but rapidly after the grain has been
ground. The hull, apparently, prevents the grain from becoming rancid by protecting tile bran
layers from mechanical damage during harvesting and subsequent handling.
THE GERM
The germ is a separate structure that generally can be easily separated from the rest of the
cereal grain. However, the scutellar epithelium (located next to the endosperm) has finger
like cells. The free ends protrude toward the adjacent starch endosperm cells and form all
amorphous cementing layers between the germ and endosperm. If part of the layer projects
into the spaces between the fingerlike cells of the scutellar epithelium and into the folds of
the scutellar structure, it may be difficult to separate the germ from the endosperm unless the
cementing layer is softened. The softening may be accomplished by steeping in corn wet
milling or by conditioning in wheat milling. In rice, a layer of crushed cells separating the
scutellar epithelium from the starchy endosperm provides a line of easy fracture.
Germ separation is also enhanced by the fact that the germ takes up water faster and swells
more readily than the endosperm. The strains resulting from differential swelling contribute to
easy separation in milling.
COMPOSITION
Like that of other foods of plant origin, the chemical composition of the dry matter of different
cereal grains varies widely. Variations are encountered in the relative amounts of proteins,
lipids, carbohydrates, pigments, vitamins, and ash; mineral elements present also vary
widely. As a food group, cereals-are characterized by relatively low protein and high
carbohydrate contents; the carbohydrates consist, essentially of starch (90% or more),
dextrins, pentosans, and sugars.
Table 4-2 Weight, Ash, Protein, Lipid and Crude Fiber Contents of main anatomical
parts of the wheat kernel and flours of different milling extraction rates.
Parameter
(%)
Wheat Kernel Fractions Milling Extraction (%)
PericarpAleurone
Layer
Starchy
Endosperm
Germ
Weight 9 8 80 3 75 83 100
Ash 3 16 0.5 5 0.5 1 1.5
Protein 5 18 10 26 11 12 12
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 10 of 162
Lipid 1 9 1 10 1 1.5 2
Crude
Fiber
21 7 >0.5 3 >0.5 0.5 2
The various components are not, uniformly distributed in the different kernel structures. Table
4-2 compares the weights and compositions of the main anatomical parts of the wheat kernel
with the composition of flours, which vary in milling extraction rate. The hulls and pericarp are
high in cellulose, pentosans, and ash; the germ is high in lipid content and rich in proteins,
sugars, and ash constituents. The endosperm contains the starch and is lower in protein
content than the germ and, in some cereals, bran; it is also low in crude fat and ash
constituents is greatly reduced by the milling processes used to prepare refined food. In
these processes, hulls, germ, and bran which are the structures rich in minerals and
vitamins, are more or less completely removed.
All cereal grains contain vitamins of the B group, but all are completely lacking in vitamin C
(unless the grain is sprouted) and vitamin D. Yellow corn differs from white corn and the
other cereal grains in containing carotenoid pigments (principally cryptoxanthin, with smaller
quantities of carotenes), which are convertible in the body to vitamin A. Wheat also contains
yellow pigments, but they are almost entirely xanthophylls, which are not precursors of
vitamin A. The oils of the embryos of cereal grains are rich sources of vitamin E. The relative
distribution of vitamins in kernel structures is not uniform, although the endosperm invariably
contains the least.
Protein contents of wheat and barley are important indexes of their quality for manufacture of
various foods. The bread-making potentialities of bread wheat are largely associated with the
quantity and quality of its protein. The cereal grains contain water-soluble proteins
(albumins), salt-soluble proteins (globulins), alcohol-soluble proteins (prolamins), and acid
and alkali-soluble proteins (glutelins). The prolamins are characteristics of the grass family
and, together with the glutelins, comprise the bulk of the proteins of cereal grain. The
following are names given to prolamins in proteins of the cereal grains: gliadin in wheat,
hordein in barley, zein in maize, avenin in oats, kafferin in grain sorghum, and secalin in rye.
The various proteins are not distributed uniformly in the kernel. Thus, the proteins
fractionated from the inner endosperm of wheat consist chiefly of a prolamin (gliadin) and
glutelin (glutelin), apparently in approximately equal amounts. The embryo proteins consist of
nucleoproteins, an albumin (leucosin), a globulin, and proteoses, whereas in wheat bran a
prolamin predominates with smaller quantities of albumins and globulins. When water is
added, the wheat endosperm proteins, gliadin and glutenin, form a tenacious colloidal
complex, known as gluten (see Figure 4- 1).
Gluten is responsible for the superiority of wheat over the other cereals for the manufacture
of leavened products, since it makes possible the formation of a dough that retains the
carbon dioxide produced by yeast or chemical leavening agents
The gluten proteins collectively contain about 17.55% nitrogen; hence, in estimating the
crude protein content of wheat and wheat products from the determination of total nitrogen,
the factor 5.7 is normally employed rather than the customary value of 6.25, which is based
on the assumption that, on the average proteins contain 16% nitrogen.
As a class, cereal proteins are not so high in biological value as those of certain legumes,
nuts, or animal products. Zein, the prolamin of corn, lacks lysine and is low in tryptophan.
The limiting amino acid in wheat endosperm proteins is lysine. While biological values of the
proteins of entire cereal grains are greater than those of the refined mill products, which
consist chiefly of the endosperm, the American and North European diets normally include
e-- [email protected] Page 10 of 162
Lipid 1 9 1 10 1 1.5 2
Crude
Fiber
21 7 >0.5 3 >0.5 0.5 2
The various components are not, uniformly distributed in the different kernel structures. Table
4-2 compares the weights and compositions of the main anatomical parts of the wheat kernel
with the composition of flours, which vary in milling extraction rate. The hulls and pericarp are
high in cellulose, pentosans, and ash; the germ is high in lipid content and rich in proteins,
sugars, and ash constituents. The endosperm contains the starch and is lower in protein
content than the germ and, in some cereals, bran; it is also low in crude fat and ash
constituents is greatly reduced by the milling processes used to prepare refined food. In
these processes, hulls, germ, and bran which are the structures rich in minerals and
vitamins, are more or less completely removed.
All cereal grains contain vitamins of the B group, but all are completely lacking in vitamin C
(unless the grain is sprouted) and vitamin D. Yellow corn differs from white corn and the
other cereal grains in containing carotenoid pigments (principally cryptoxanthin, with smaller
quantities of carotenes), which are convertible in the body to vitamin A. Wheat also contains
yellow pigments, but they are almost entirely xanthophylls, which are not precursors of
vitamin A. The oils of the embryos of cereal grains are rich sources of vitamin E. The relative
distribution of vitamins in kernel structures is not uniform, although the endosperm invariably
contains the least.
Protein contents of wheat and barley are important indexes of their quality for manufacture of
various foods. The bread-making potentialities of bread wheat are largely associated with the
quantity and quality of its protein. The cereal grains contain water-soluble proteins
(albumins), salt-soluble proteins (globulins), alcohol-soluble proteins (prolamins), and acid
and alkali-soluble proteins (glutelins). The prolamins are characteristics of the grass family
and, together with the glutelins, comprise the bulk of the proteins of cereal grain. The
following are names given to prolamins in proteins of the cereal grains: gliadin in wheat,
hordein in barley, zein in maize, avenin in oats, kafferin in grain sorghum, and secalin in rye.
The various proteins are not distributed uniformly in the kernel. Thus, the proteins
fractionated from the inner endosperm of wheat consist chiefly of a prolamin (gliadin) and
glutelin (glutelin), apparently in approximately equal amounts. The embryo proteins consist of
nucleoproteins, an albumin (leucosin), a globulin, and proteoses, whereas in wheat bran a
prolamin predominates with smaller quantities of albumins and globulins. When water is
added, the wheat endosperm proteins, gliadin and glutenin, form a tenacious colloidal
complex, known as gluten (see Figure 4- 1).
Gluten is responsible for the superiority of wheat over the other cereals for the manufacture
of leavened products, since it makes possible the formation of a dough that retains the
carbon dioxide produced by yeast or chemical leavening agents
The gluten proteins collectively contain about 17.55% nitrogen; hence, in estimating the
crude protein content of wheat and wheat products from the determination of total nitrogen,
the factor 5.7 is normally employed rather than the customary value of 6.25, which is based
on the assumption that, on the average proteins contain 16% nitrogen.
As a class, cereal proteins are not so high in biological value as those of certain legumes,
nuts, or animal products. Zein, the prolamin of corn, lacks lysine and is low in tryptophan.
The limiting amino acid in wheat endosperm proteins is lysine. While biological values of the
proteins of entire cereal grains are greater than those of the refined mill products, which
consist chiefly of the endosperm, the American and North European diets normally include
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 11 of 162
various cereals, as well as animal products. Under those conditions, different proteins tend to
supplement each other, and the cereals are important and valuable sources of amino acids
for the synthesis of body proteins.
In most cereal grains, as total protein contents increases to about 14% the concentration of
the albumins plus globulins (and consequently of lysine) in the protein decreases.
The main form of carbohydrate is starch, which is the main source of calories provided by the
grains. The major portion of the carbohydrates is in the starchy endosperm.
Fatty acids in cereals occur in three main types-neutral lipids, glycolipids, and phospholipids.
The lipids in cereals are relatively rich in the essential fatty acid, linoleic acid. Saturated fatty
acids (mainly palmitic) represent less than 25% of the total fatty acids for most grains.
In summary, cereal grains are a diversified and primary source of nutrients. Their high starch
contents make them major contributors of calories; they also contribute to our needs for
proteins, lipids, vitamins, and minerals. Vitamins and minerals lost during milling into refined
food products (wheat flour or white rice) can be (and in many countries are) replaced by
nutrient fortification. The composition of cereal grains and their milled products make them
uniquely suited in the production of wholesome, nutritional, and consumer-acceptable foods.
COMPOSITION OF WHEAT
Table 1.2 Range of Major Components in Wheat
Determination Range of Analytical Results, %
Low High
Protein (N x 5.7) 7.0 18.0
Mineral Matter (Ash) 1.5 2.0
Lipids (Fat) 1.5 2.0
Starch 60.0 68.0
Cellulose (Crude Fiber) 2.0 2.5
WHEAT FLOUR PROTEINS
NON GLUTEN
-15%
-Non Dough Forming
GLUTEN
-85%
-Dough Forming
GLIADIN GLUTENIN
-ALBUMINS (60%)
-GLOBULINS (40%)
-PEPTIDES
-AMINO ACIDS
-Flour enzymes
-Soluble, foaming proteins
-Coagulable proteins
HIGH MOLECULAR
WEIGHT
(>1,00,000)
LOW MOLECULAR
WEIGHT
(25,000 – 1,00,000)
GLIADIN SPECIES
-Extensible
-Low elasticity
-Soluble in acids, bases,
hydrogen bonding solvents
GLUTENIN SPECIES
-Low extensibility
-Elastic
- Suspendable in acids, bases, hydrogen
bonding solvents
-Complexes with lipids
e-- [email protected] Page 11 of 162
various cereals, as well as animal products. Under those conditions, different proteins tend to
supplement each other, and the cereals are important and valuable sources of amino acids
for the synthesis of body proteins.
In most cereal grains, as total protein contents increases to about 14% the concentration of
the albumins plus globulins (and consequently of lysine) in the protein decreases.
The main form of carbohydrate is starch, which is the main source of calories provided by the
grains. The major portion of the carbohydrates is in the starchy endosperm.
Fatty acids in cereals occur in three main types-neutral lipids, glycolipids, and phospholipids.
The lipids in cereals are relatively rich in the essential fatty acid, linoleic acid. Saturated fatty
acids (mainly palmitic) represent less than 25% of the total fatty acids for most grains.
In summary, cereal grains are a diversified and primary source of nutrients. Their high starch
contents make them major contributors of calories; they also contribute to our needs for
proteins, lipids, vitamins, and minerals. Vitamins and minerals lost during milling into refined
food products (wheat flour or white rice) can be (and in many countries are) replaced by
nutrient fortification. The composition of cereal grains and their milled products make them
uniquely suited in the production of wholesome, nutritional, and consumer-acceptable foods.
COMPOSITION OF WHEAT
Table 1.2 Range of Major Components in Wheat
Determination Range of Analytical Results, %
Low High
Protein (N x 5.7) 7.0 18.0
Mineral Matter (Ash) 1.5 2.0
Lipids (Fat) 1.5 2.0
Starch 60.0 68.0
Cellulose (Crude Fiber) 2.0 2.5
WHEAT FLOUR PROTEINS
NON GLUTEN
-15%
-Non Dough Forming
GLUTEN
-85%
-Dough Forming
GLIADIN GLUTENIN
-ALBUMINS (60%)
-GLOBULINS (40%)
-PEPTIDES
-AMINO ACIDS
-Flour enzymes
-Soluble, foaming proteins
-Coagulable proteins
HIGH MOLECULAR
WEIGHT
(>1,00,000)
LOW MOLECULAR
WEIGHT
(25,000 – 1,00,000)
GLIADIN SPECIES
-Extensible
-Low elasticity
-Soluble in acids, bases,
hydrogen bonding solvents
GLUTENIN SPECIES
-Low extensibility
-Elastic
- Suspendable in acids, bases, hydrogen
bonding solvents
-Complexes with lipids
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 12 of 162
Moisture 8.0 18.0
Wheat composition can vary considerably from one area to another as well as from year to
year within any given area. A fairly typical range in composition of wheat samples within the
U.S. in one crop year is indicated in Table 1.2. Samples represented many different varieties
of all commercial grades.
In addition to publications on the proximate composition of wheat, which indicate only broad
classes of chemical constituents, a vast amount of analytical data has been assembled on
the amino acid content of wheat proteins, the elements constituting the ash or mineral
matter, enzyme activity, vitamin content, and the properties of wheat starch and other
carbohydrate materials.
Proteins
The uniqueness of wheat among cereal grains depends mostly upon the characteristics of its
protein content. In wheat, as in other plants, protein is developed from simpler substances
extracted from the environment. As a plant develops from a seed, two metabolic processes
take place in the cells--photosynthesis and nitrogen fixation.
Photosynthesis involves formation of carbohydrates from carbon dioxide, water, and energy
while nitrogen fixation is the conversion of nitrogen gas into chemically combined nitrogen
that can readily assimilated by the plant.
Nitrogen fixation can be carried out by legumes, which bear root nodules containing certain
kinds of bacteria, by some algae, by chemical synthesis, or by electrical discharges in the
atmosphere (lightning). Recent research seems to indicate that a minor amount (at least) of
nitrogen fixation may occur in many more plant species than previously recognized but, even
so, almost all the protein made by the wheat plant is based on soluble nitrogen compounds
absorbed through the roots. These relatively simple compounds are transformed into
proteins by enzymic processes and the proteins then used as part of the structural materials
and protective tissues of the seed, and as enzymes and storage proteins. The latter will
ultimately be used in constructing some of the tissues of the new plant, which emerges from
the seed as it sprouts.
The proteins of wheat are complex, and there is no simple explanation of their constitution or
biological function. Neither difference in the amounts of the various classes of proteins nor
differences in the amount or kind of amino acids account for the wide variations in baking
properties of flours.
The storage proteins in wheat kernels are the source of gluten, which is the complex of
nitrogenous compounds that give wheat flour dough its cohesive and elastic properties.
Gluten can be separated from wheat flour by making a stiff dough from a mixture of flour and
water, then washing (manually or mechanically) this dough in an excess of water (as in a
stream of water) until the starch granules and all soluble materials have been removed.
Gluten appears to be a mixture of two major components called glutenin and gliadin. The
gliadin fraction is soluble in neutral 70% aqueous ethanol. It consists mainly of monomeric
proteins that associate by noncovalent hydrogen bonding and by hydrophobic interactions,
but also contains polymeric proteins that are related structurally to some glutenin subunits.
The glutenins are essentially insoluble in 70% ethanol, and appear to consist of proteins or
subunits that are aggregated into high molecular weight polymers by covalent disulfide
bonds.
e-- [email protected] Page 12 of 162
Moisture 8.0 18.0
Wheat composition can vary considerably from one area to another as well as from year to
year within any given area. A fairly typical range in composition of wheat samples within the
U.S. in one crop year is indicated in Table 1.2. Samples represented many different varieties
of all commercial grades.
In addition to publications on the proximate composition of wheat, which indicate only broad
classes of chemical constituents, a vast amount of analytical data has been assembled on
the amino acid content of wheat proteins, the elements constituting the ash or mineral
matter, enzyme activity, vitamin content, and the properties of wheat starch and other
carbohydrate materials.
Proteins
The uniqueness of wheat among cereal grains depends mostly upon the characteristics of its
protein content. In wheat, as in other plants, protein is developed from simpler substances
extracted from the environment. As a plant develops from a seed, two metabolic processes
take place in the cells--photosynthesis and nitrogen fixation.
Photosynthesis involves formation of carbohydrates from carbon dioxide, water, and energy
while nitrogen fixation is the conversion of nitrogen gas into chemically combined nitrogen
that can readily assimilated by the plant.
Nitrogen fixation can be carried out by legumes, which bear root nodules containing certain
kinds of bacteria, by some algae, by chemical synthesis, or by electrical discharges in the
atmosphere (lightning). Recent research seems to indicate that a minor amount (at least) of
nitrogen fixation may occur in many more plant species than previously recognized but, even
so, almost all the protein made by the wheat plant is based on soluble nitrogen compounds
absorbed through the roots. These relatively simple compounds are transformed into
proteins by enzymic processes and the proteins then used as part of the structural materials
and protective tissues of the seed, and as enzymes and storage proteins. The latter will
ultimately be used in constructing some of the tissues of the new plant, which emerges from
the seed as it sprouts.
The proteins of wheat are complex, and there is no simple explanation of their constitution or
biological function. Neither difference in the amounts of the various classes of proteins nor
differences in the amount or kind of amino acids account for the wide variations in baking
properties of flours.
The storage proteins in wheat kernels are the source of gluten, which is the complex of
nitrogenous compounds that give wheat flour dough its cohesive and elastic properties.
Gluten can be separated from wheat flour by making a stiff dough from a mixture of flour and
water, then washing (manually or mechanically) this dough in an excess of water (as in a
stream of water) until the starch granules and all soluble materials have been removed.
Gluten appears to be a mixture of two major components called glutenin and gliadin. The
gliadin fraction is soluble in neutral 70% aqueous ethanol. It consists mainly of monomeric
proteins that associate by noncovalent hydrogen bonding and by hydrophobic interactions,
but also contains polymeric proteins that are related structurally to some glutenin subunits.
The glutenins are essentially insoluble in 70% ethanol, and appear to consist of proteins or
subunits that are aggregated into high molecular weight polymers by covalent disulfide
bonds.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 13 of 162
Proteins with enzyme activity are the albumins and globulins located in the embryo,
aleurone, and endosperm.
The protein content of wheat kernels is affected both by the genetic constitution of the plant
and by environmental conditions during growth of the plant and development of the seed.
Typically, hard red spring wheat and durum will analyze about 13 to 17% protein. Hard red
winter wheat will test out at 11 to 15% protein, in most cases. Soft winter wheat and club
wheat would ordinarily fall in the range of 7 to 11% protein. Of course, in the normal course
of events, many samples will be found that fall outside this range because of unusual
weather events, heavy fertilizer applications, disease, or characteristics of a particular
variety.
The total protein of the wheat kernel is not a well-balanced nutrient so far as the human diet
is concerned. It has a PER far below that of egg or milk, for example, although its protein
quality is within the same range as most other cereals. The limiting amino acid is lysine,
as is the case with most cereal proteins. Generally speaking, the more refined the product,
the less lysine is present. Germ contains the most. Various attempts have been made to
develop strains of wheat, which have better than average protein quality, particularly by
increasing the content of lysine. Some success has been achieved, but high lysine strains
generally have other defects, such as poor yield, reduced bread making quality, etc.
Carbohydrates
Starch is the carbohydrate present in the greatest amount in the mature wheat kernel;
in fact, it exceeds all other types of compounds, being several times larger than the next
largest class of substances. It is formed out of carbon dioxide and water by the process of
photosynthesis and is deposited in plant cells as microscopic particles of varying size and
conformation. Many genes are involved in determining the shape, crystalline pattern, and
chemical properties of starch granules. Starch is a polymer of D-glucose, most of the hexose
units being joined together by α-(1-4) bonds. There are varying proportions of amylose and
amylopectin, the former being virtually a straight chain, but with a few branch points, while
the latter contains numerous side chains attached by 4 to 5% α-(1-6)-D-glucosidic linkages
and has a molecular weight greater than about 10
8
.
The starch granules grow in the developing endosperm as single entities in amyloplasts. In
wheat starch, they have a bimodal size distribution, with about 3 to 4% (50 to 75% by weight)
being lenticular and 15 to 40 microns in size and the remainder being small, approximately
spherical, granules, ranging in size from about 1 to 10 microns. In spite of the apparent
bimodal distribution, there is actually a continuous gradation in size of granules from smallest
to largest, especially evident during development of the kernel, as would be expected since
the sudden appearance of large granules without any intermediate growth stages would
indeed be a curious phenomenon. In the ripened kernel, though, the intermediate size
granules are not numerous, constituting in many cases only a fractional percentage of the
total weight of starch.
Polysaccharides other than starch are found in cell walls of the parenchymatous and lignified
tissues of the wheat plant. In the cell wall parenchymatous tissues, they are mainly the
arabinoxylans and the soluble β-D- glucans. Small amounts of cellulose and
glucomannans may be present, but pectins and pectic substances are absent. Wheat
endosperm is comparatively rich in arabinoxylan and very low in β-D-glucans. Cell walls of
the lignified bran layers of the kernels contain appreciable amounts of cellulose.
Arabinoxylans are present in the endosperm. Lignin and protein can be found in the isolated
polysaccharide fraction (Lineback and Rasper 1988). ,
e-- [email protected] Page 13 of 162
Proteins with enzyme activity are the albumins and globulins located in the embryo,
aleurone, and endosperm.
The protein content of wheat kernels is affected both by the genetic constitution of the plant
and by environmental conditions during growth of the plant and development of the seed.
Typically, hard red spring wheat and durum will analyze about 13 to 17% protein. Hard red
winter wheat will test out at 11 to 15% protein, in most cases. Soft winter wheat and club
wheat would ordinarily fall in the range of 7 to 11% protein. Of course, in the normal course
of events, many samples will be found that fall outside this range because of unusual
weather events, heavy fertilizer applications, disease, or characteristics of a particular
variety.
The total protein of the wheat kernel is not a well-balanced nutrient so far as the human diet
is concerned. It has a PER far below that of egg or milk, for example, although its protein
quality is within the same range as most other cereals. The limiting amino acid is lysine,
as is the case with most cereal proteins. Generally speaking, the more refined the product,
the less lysine is present. Germ contains the most. Various attempts have been made to
develop strains of wheat, which have better than average protein quality, particularly by
increasing the content of lysine. Some success has been achieved, but high lysine strains
generally have other defects, such as poor yield, reduced bread making quality, etc.
Carbohydrates
Starch is the carbohydrate present in the greatest amount in the mature wheat kernel;
in fact, it exceeds all other types of compounds, being several times larger than the next
largest class of substances. It is formed out of carbon dioxide and water by the process of
photosynthesis and is deposited in plant cells as microscopic particles of varying size and
conformation. Many genes are involved in determining the shape, crystalline pattern, and
chemical properties of starch granules. Starch is a polymer of D-glucose, most of the hexose
units being joined together by α-(1-4) bonds. There are varying proportions of amylose and
amylopectin, the former being virtually a straight chain, but with a few branch points, while
the latter contains numerous side chains attached by 4 to 5% α-(1-6)-D-glucosidic linkages
and has a molecular weight greater than about 10
8
.
The starch granules grow in the developing endosperm as single entities in amyloplasts. In
wheat starch, they have a bimodal size distribution, with about 3 to 4% (50 to 75% by weight)
being lenticular and 15 to 40 microns in size and the remainder being small, approximately
spherical, granules, ranging in size from about 1 to 10 microns. In spite of the apparent
bimodal distribution, there is actually a continuous gradation in size of granules from smallest
to largest, especially evident during development of the kernel, as would be expected since
the sudden appearance of large granules without any intermediate growth stages would
indeed be a curious phenomenon. In the ripened kernel, though, the intermediate size
granules are not numerous, constituting in many cases only a fractional percentage of the
total weight of starch.
Polysaccharides other than starch are found in cell walls of the parenchymatous and lignified
tissues of the wheat plant. In the cell wall parenchymatous tissues, they are mainly the
arabinoxylans and the soluble β-D- glucans. Small amounts of cellulose and
glucomannans may be present, but pectins and pectic substances are absent. Wheat
endosperm is comparatively rich in arabinoxylan and very low in β-D-glucans. Cell walls of
the lignified bran layers of the kernels contain appreciable amounts of cellulose.
Arabinoxylans are present in the endosperm. Lignin and protein can be found in the isolated
polysaccharide fraction (Lineback and Rasper 1988). ,
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 14 of 162
Mono- and disaccharides are present, but in very small amounts. As a percentage of dry
matter, the following values may be considered fairly representative of wheat kernels:
fructose 0.06, glucose, 0.08, galactose 0.02, sucrose 0.54, difructose 0.26, and maltose
0.05. Raffinose has been reported as being present at about 0.19%. Table 1.5 gives
the results of a compilation of numerous analyses performed by several laboratories
investigating the carbohydrate content of wheat kernels.
Table-1.5 Sugars and Polysaccharides in Wheat Kernels
Component Content Component Content
Total Alcohol Soluble Sugars2.15 - 3.96Glucose 0.03 - 0.09
Glucofructosans 0.94 - 1.14Fructose 0.06 - 0.08
Raffinose 0.19 - 0.68Galactose 0.02
Glucodifructose 0.26 - 0.41Starch 62.9 - 75.0
Maltose 0.01 - 0.18Crude Fiber 1.70 - 3.02
Sucrose 0.54 - 1.55Pentosans 5.57 - 9.00
Lipids
Among the lipids reported to have been found in wheat kernels are free fatty acids, simple
glycerides, galactosylglycerides, phosphoglycerides, sterol lipids, sphingolipids, diol
lipids, tocopherols, carotenoids, wax esters, and hydrocarbons. In amount, the principal
lipids are acyl lipids containing the fatty acids palmitic, stearic, oleic, linoleic, and α-
linolenic. Reports have indicated minor amounts of many other fatty acids. The principal
glyceride in wheat is triglyceride, with minor amounts of diglyceride and monoglyceride. The
glycolipids consist of glycosylglycerides, sterylglycosides, and glycosylceramides. The
ubiquitous plant phosphoglycerides are present, phosphatidylcholine,
phosphatidylethanolamine, phosphatidylinositol, phosphatidylglycerol, phosphatidic
acid, most of the corresponding monoacyl derivatives of lysophospholipids, and N-acyl
phosphohpids. The principal sterols are the C29 and C28 4-dimethyl sterols sitosterol and
campesterol. Significant amounts of cholesterol have occasionally been reported, but there is
not universal agreement these results are accurate. Most of the sphingolipids consist of
ceramide and a series of ceramide glycosides, containing no phosphorus. Acylated diols
(with C2 to C5) have been reported in wheat (Morrison 1988).
Minerals
Minerals form a small part of the wheat kernel and an even smaller proportion of the
endosperm-less than 1%. Major constituents of the mineral fraction are the phosphates and
sulfates of potassium, magnesium, and calcium. Some of the phosphate is present in the
form of phytic acid. There are significant quantities of iron, manganese, zinc, and copper as
well as trace amounts of many other elements. One report shows the following ranges, in mg
per kg, for wheat: iron 18-31, zinc 21-63, copper 1.8-6.2, manganese, 24-37, and
selenium 0.04-0.71. Hard wheat generally contains more of these elements than soft wheat.
Potassium is present at about 0.37% in whole soft wheat (air dry basis), magnesium at
0.1.5%, phosphorus at 0.42%, and calcium at 335 ppm (O’Dell et al. 1972). The sodium
content of wheat is quite low.
The results of one extensive set of analyses are reproduced in Table 1.7.
TABLE 1.7 MINERAL AND PHYTATE CONTENT OF WHEAT KERNELS
Element or
Compound
and Unit
CONTENT IN KERNEL OR PART
Whole
Kernel
Germ Endosperm Aleurone Hull
e-- [email protected] Page 14 of 162
Mono- and disaccharides are present, but in very small amounts. As a percentage of dry
matter, the following values may be considered fairly representative of wheat kernels:
fructose 0.06, glucose, 0.08, galactose 0.02, sucrose 0.54, difructose 0.26, and maltose
0.05. Raffinose has been reported as being present at about 0.19%. Table 1.5 gives
the results of a compilation of numerous analyses performed by several laboratories
investigating the carbohydrate content of wheat kernels.
Table-1.5 Sugars and Polysaccharides in Wheat Kernels
Component Content Component Content
Total Alcohol Soluble Sugars2.15 - 3.96Glucose 0.03 - 0.09
Glucofructosans 0.94 - 1.14Fructose 0.06 - 0.08
Raffinose 0.19 - 0.68Galactose 0.02
Glucodifructose 0.26 - 0.41Starch 62.9 - 75.0
Maltose 0.01 - 0.18Crude Fiber 1.70 - 3.02
Sucrose 0.54 - 1.55Pentosans 5.57 - 9.00
Lipids
Among the lipids reported to have been found in wheat kernels are free fatty acids, simple
glycerides, galactosylglycerides, phosphoglycerides, sterol lipids, sphingolipids, diol
lipids, tocopherols, carotenoids, wax esters, and hydrocarbons. In amount, the principal
lipids are acyl lipids containing the fatty acids palmitic, stearic, oleic, linoleic, and α-
linolenic. Reports have indicated minor amounts of many other fatty acids. The principal
glyceride in wheat is triglyceride, with minor amounts of diglyceride and monoglyceride. The
glycolipids consist of glycosylglycerides, sterylglycosides, and glycosylceramides. The
ubiquitous plant phosphoglycerides are present, phosphatidylcholine,
phosphatidylethanolamine, phosphatidylinositol, phosphatidylglycerol, phosphatidic
acid, most of the corresponding monoacyl derivatives of lysophospholipids, and N-acyl
phosphohpids. The principal sterols are the C29 and C28 4-dimethyl sterols sitosterol and
campesterol. Significant amounts of cholesterol have occasionally been reported, but there is
not universal agreement these results are accurate. Most of the sphingolipids consist of
ceramide and a series of ceramide glycosides, containing no phosphorus. Acylated diols
(with C2 to C5) have been reported in wheat (Morrison 1988).
Minerals
Minerals form a small part of the wheat kernel and an even smaller proportion of the
endosperm-less than 1%. Major constituents of the mineral fraction are the phosphates and
sulfates of potassium, magnesium, and calcium. Some of the phosphate is present in the
form of phytic acid. There are significant quantities of iron, manganese, zinc, and copper as
well as trace amounts of many other elements. One report shows the following ranges, in mg
per kg, for wheat: iron 18-31, zinc 21-63, copper 1.8-6.2, manganese, 24-37, and
selenium 0.04-0.71. Hard wheat generally contains more of these elements than soft wheat.
Potassium is present at about 0.37% in whole soft wheat (air dry basis), magnesium at
0.1.5%, phosphorus at 0.42%, and calcium at 335 ppm (O’Dell et al. 1972). The sodium
content of wheat is quite low.
The results of one extensive set of analyses are reproduced in Table 1.7.
TABLE 1.7 MINERAL AND PHYTATE CONTENT OF WHEAT KERNELS
Element or
Compound
and Unit
CONTENT IN KERNEL OR PART
Whole
Kernel
Germ Endosperm Aleurone Hull
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 15 of 162
Total P, % 0.42 1.66 0.11 1.39 0.08
Phytate P, %0.32 1.10 0.001 1.16 0
Zn, ppm 40.4 222 14.1 119 88.7
Fe, ppm 54.6 235 21.5 186 110
Mn, ppm 56.4 402 8.80 130 182
Cu, ppm 4.25 18 2.80 12 22.6
Ca, ppm 335 1760 173 730 2570
Mg, % 0.15 0.54 0.02 0.58 0.13
K, % 0.37 0.91 0.12 1.10 0.24
The kernel was composed of 3.5% germ, 70.5% Endosperm, 23% Aleurone and 3%
Hull.
All analysis reported on air dry weight.
Bioavailability of the wheat minerals must be considered in any nutritional evaluation of the
grain. Phytate, most of which is found in the aleurone layer, forms insoluble complexes
with some minerals, and these complexes are poorly absorbed from the digestive
tract. Zinc may be rendered totally unavailable by this effect, and the availability of other
essential minerals may be adversely affected. Calcium is said to increase the binding effect
of phytin on zinc.
Vitamins
There are considerable variations in published figures for the vitamin content of wheat, but
the grain is considered to be a significant source of the vitamins thiamin, niacin, and Bs.
Davis et al. 1981 reported the vitamin content of 406 wheat cultivars from five market
classes. The mean values, in mg per kg, were 4.6 for thiamin, 1.3 for riboflavin, 55 for
niacin, and 4.6 for pyridoxine. Ranges were 3.3 to 6.5, 1.0 to 1.7, 38 to 93 and 1.6 to 7.9,
respectively. From another source, content in a wheat sample (HRS) of other vitamins in mg
per kg on a dry weight basis were, biotin 0.056, folacin 0.56, and pantothenic acid 9.1.
The content of vitamin A is known to be negligible, but the germ is one of the richest
known sources of vitamin E. In one large sample of wheat, the total tocopherols ranged
from 4.9 to 40.1 mg per kg.
Fiber
As with all discussions of dietary fiber, quantitative presentations are clouded by the almost
continual changes in definition and concept of this category of substances which have
occurred over the past decade or so, as well as by the lack of standardization in test
conditions which existed until quite recently. Wheat endosperm contains only minor amounts
of substances, which could be called fiber even by the most liberal definition, and this
consideration carries through to white flour. Wheat flour (containing some of the outer layers)
and whole-wheat flour (containing all the fractions in the same proportion as in the kernel)
are somewhat better, but are not superior, sources of dietary fiber. White flour, whole-
wheat flour, and wheat bran contain, on the average, 2.78%, 12.57%, and 42.65% dietary
fiber (dry matter basis) according to Cumming and Englyst (1987).
Pigments
Ripe wheat grain varies from light buff or yellow to red-brown, according to the amount of red
pigmentation in the seed coat. The color will vary little in true breeding cultivars, allowing
wheat varieties to be reliably classified as red or white. Red pigmentation is controlled by
three genetic loci, with the result that depth of color can vary between varieties classified as
red. The amber color of some durum wheats results from the endosperm pigments showing
through the translucent exterior layers. Nearly all bread wheat grown in the U.S. is red, but
Australia produces white wheat exclusively. Canadian wheat is all, or nearly all, of the red
e-- [email protected] Page 15 of 162
Total P, % 0.42 1.66 0.11 1.39 0.08
Phytate P, %0.32 1.10 0.001 1.16 0
Zn, ppm 40.4 222 14.1 119 88.7
Fe, ppm 54.6 235 21.5 186 110
Mn, ppm 56.4 402 8.80 130 182
Cu, ppm 4.25 18 2.80 12 22.6
Ca, ppm 335 1760 173 730 2570
Mg, % 0.15 0.54 0.02 0.58 0.13
K, % 0.37 0.91 0.12 1.10 0.24
The kernel was composed of 3.5% germ, 70.5% Endosperm, 23% Aleurone and 3%
Hull.
All analysis reported on air dry weight.
Bioavailability of the wheat minerals must be considered in any nutritional evaluation of the
grain. Phytate, most of which is found in the aleurone layer, forms insoluble complexes
with some minerals, and these complexes are poorly absorbed from the digestive
tract. Zinc may be rendered totally unavailable by this effect, and the availability of other
essential minerals may be adversely affected. Calcium is said to increase the binding effect
of phytin on zinc.
Vitamins
There are considerable variations in published figures for the vitamin content of wheat, but
the grain is considered to be a significant source of the vitamins thiamin, niacin, and Bs.
Davis et al. 1981 reported the vitamin content of 406 wheat cultivars from five market
classes. The mean values, in mg per kg, were 4.6 for thiamin, 1.3 for riboflavin, 55 for
niacin, and 4.6 for pyridoxine. Ranges were 3.3 to 6.5, 1.0 to 1.7, 38 to 93 and 1.6 to 7.9,
respectively. From another source, content in a wheat sample (HRS) of other vitamins in mg
per kg on a dry weight basis were, biotin 0.056, folacin 0.56, and pantothenic acid 9.1.
The content of vitamin A is known to be negligible, but the germ is one of the richest
known sources of vitamin E. In one large sample of wheat, the total tocopherols ranged
from 4.9 to 40.1 mg per kg.
Fiber
As with all discussions of dietary fiber, quantitative presentations are clouded by the almost
continual changes in definition and concept of this category of substances which have
occurred over the past decade or so, as well as by the lack of standardization in test
conditions which existed until quite recently. Wheat endosperm contains only minor amounts
of substances, which could be called fiber even by the most liberal definition, and this
consideration carries through to white flour. Wheat flour (containing some of the outer layers)
and whole-wheat flour (containing all the fractions in the same proportion as in the kernel)
are somewhat better, but are not superior, sources of dietary fiber. White flour, whole-
wheat flour, and wheat bran contain, on the average, 2.78%, 12.57%, and 42.65% dietary
fiber (dry matter basis) according to Cumming and Englyst (1987).
Pigments
Ripe wheat grain varies from light buff or yellow to red-brown, according to the amount of red
pigmentation in the seed coat. The color will vary little in true breeding cultivars, allowing
wheat varieties to be reliably classified as red or white. Red pigmentation is controlled by
three genetic loci, with the result that depth of color can vary between varieties classified as
red. The amber color of some durum wheats results from the endosperm pigments showing
through the translucent exterior layers. Nearly all bread wheat grown in the U.S. is red, but
Australia produces white wheat exclusively. Canadian wheat is all, or nearly all, of the red
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 16 of 162
type. In some emmer wheats, a purplish kernel color has been observed. Soft, chalky
endosperm increases the paleness of white wheats and decreased the color of red
wheats, while hard, vitreous endosperm has the opposite effect.
The endosperm of wheat has a pale yellow color, which is slightly more intense in hard
wheat, as compared to soft wheat, and durum has even more color. The outer layers of
wheat have a slight red to dark brown color, depending on the cultivar. These pigments are
not desired in white bread, but the yellow color is much less objectionable than the
grayish effect given by bran particles. The yellow color is highly desirable in pasta,
however, and therefore is a quality factor in durum semolina. Bran specks are at least
as objectionable in pasta as in bread, and probably more so.
The yellow pigments are primarily carotenoids, hydroxylated xanthophylls (lutein),
mono- and di-esters of lutein, and flavones (primarily tricin). Very small amounts of
other xanthine compounds and chlorophyll decomposition products have also been
reported. The bleaching agents used on some types of flour oxidize carotene; nutritionally
this is not important since there is not enough provitamin A in flour to be a significant source
for humans. Xanthophylls are easily oxidized to colorless compounds. Both carotenes and
xanthophylls are insoluble in water but readily dissolve in many organic solvents. Tricin is the
major flavone in wheat. The flavone pigments range in color from yellow to brown.
A preparation of the enzyme(s) called hpoxygenase is commercially available for use
as a bleaching agent in bread dough. In a rather complex series of reactions, carotene is
oxidized by this enzyme preparation, so that a lighter-colored breadcrumb is obtained.
Enzymes
There are certainly hundreds, perhaps thousands, of different kinds of enzymes in wheat,
since virtually all of the reactions, which make up the metabolic activities of the plant, are
expedited and guided by these organic catalysts. In the intact, dry, ungerminated grain, the
total enzyme activity appears to be very slight, but this picture changes dramatically when
germination begins. Then, activity becomes pronounced as new enzymes are generated and
preformed but hindered enzymes are released. The enzymes, which have received the most
attention from investigators, are the amylases, or starch-digesting enzymes, primarily
because the effects of these enzymes are so important in baking and, particularly, in malting
and brewing.
Among the carbohydrases; in cereals are α-amylases, β-amylases, debranching
enzymes, cellulases, β-glucanases, and many glucosidases. Alpha-amylase appears to
be the most important carbohydrase. Wheat also contains a large number of proteolytic
enzymes, such as endoproteolytic enzymes (cleaving peptide bonds some distance from
the ends of protein molecules) and exoproteolytic enzymes (attacking either the
carboxyl or amino termination of a protein molecule). The acid carboxypeptidases,
which are exoproteolytic enzymes reacting at the carboxyl termination, are relatively
abundant. Ester hydrolases include enzymes such as lipases, esterases, and
phosphatases; the first two are differentiated by their ability to break ester linkages from
water-insoluble esters and soluble carboxylic acid esters, respectively. Phosphatases act
primarily on esters of orthophosphoric acid.
Phytase catalyzes the hydrolysis of phytic acid to inositol and free orthophosphate.
Lipoxygenase, which catalyzes the peroxidation of certain polyunsaturated fatty acids
by molecular oxygen, is present in relatively high concentration in soybeans and is found in
wheat. Polyphenol oxidases (catechol oxidase, tyrosinase, etc.) oxidize phenols to
quinones and are evidently more concentrated in the bran than in the endosperm; some of
e-- [email protected] Page 16 of 162
type. In some emmer wheats, a purplish kernel color has been observed. Soft, chalky
endosperm increases the paleness of white wheats and decreased the color of red
wheats, while hard, vitreous endosperm has the opposite effect.
The endosperm of wheat has a pale yellow color, which is slightly more intense in hard
wheat, as compared to soft wheat, and durum has even more color. The outer layers of
wheat have a slight red to dark brown color, depending on the cultivar. These pigments are
not desired in white bread, but the yellow color is much less objectionable than the
grayish effect given by bran particles. The yellow color is highly desirable in pasta,
however, and therefore is a quality factor in durum semolina. Bran specks are at least
as objectionable in pasta as in bread, and probably more so.
The yellow pigments are primarily carotenoids, hydroxylated xanthophylls (lutein),
mono- and di-esters of lutein, and flavones (primarily tricin). Very small amounts of
other xanthine compounds and chlorophyll decomposition products have also been
reported. The bleaching agents used on some types of flour oxidize carotene; nutritionally
this is not important since there is not enough provitamin A in flour to be a significant source
for humans. Xanthophylls are easily oxidized to colorless compounds. Both carotenes and
xanthophylls are insoluble in water but readily dissolve in many organic solvents. Tricin is the
major flavone in wheat. The flavone pigments range in color from yellow to brown.
A preparation of the enzyme(s) called hpoxygenase is commercially available for use
as a bleaching agent in bread dough. In a rather complex series of reactions, carotene is
oxidized by this enzyme preparation, so that a lighter-colored breadcrumb is obtained.
Enzymes
There are certainly hundreds, perhaps thousands, of different kinds of enzymes in wheat,
since virtually all of the reactions, which make up the metabolic activities of the plant, are
expedited and guided by these organic catalysts. In the intact, dry, ungerminated grain, the
total enzyme activity appears to be very slight, but this picture changes dramatically when
germination begins. Then, activity becomes pronounced as new enzymes are generated and
preformed but hindered enzymes are released. The enzymes, which have received the most
attention from investigators, are the amylases, or starch-digesting enzymes, primarily
because the effects of these enzymes are so important in baking and, particularly, in malting
and brewing.
Among the carbohydrases; in cereals are α-amylases, β-amylases, debranching
enzymes, cellulases, β-glucanases, and many glucosidases. Alpha-amylase appears to
be the most important carbohydrase. Wheat also contains a large number of proteolytic
enzymes, such as endoproteolytic enzymes (cleaving peptide bonds some distance from
the ends of protein molecules) and exoproteolytic enzymes (attacking either the
carboxyl or amino termination of a protein molecule). The acid carboxypeptidases,
which are exoproteolytic enzymes reacting at the carboxyl termination, are relatively
abundant. Ester hydrolases include enzymes such as lipases, esterases, and
phosphatases; the first two are differentiated by their ability to break ester linkages from
water-insoluble esters and soluble carboxylic acid esters, respectively. Phosphatases act
primarily on esters of orthophosphoric acid.
Phytase catalyzes the hydrolysis of phytic acid to inositol and free orthophosphate.
Lipoxygenase, which catalyzes the peroxidation of certain polyunsaturated fatty acids
by molecular oxygen, is present in relatively high concentration in soybeans and is found in
wheat. Polyphenol oxidases (catechol oxidase, tyrosinase, etc.) oxidize phenols to
quinones and are evidently more concentrated in the bran than in the endosperm; some of
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 17 of 162
their reaction products are colored. Peroxidases and catalase are classed as
hydroperoxidases that catalyze the oxidation of certain aromatic amines and phenols by
hydrogen peroxide; they are also more active in bran than in the endosperm.
Wheat-Processing, Milling
Over two-thirds of the annual harvest of wheat is processed for food. The limited use for
industrial purposes is due mainly to its high price in relation to other cereal grains. The main
use of wheat for food is the manufacture of flour for making bread, biscuits, pastry products,
and semolina and farina for alimentary pastes. A small portion is converted into breakfast
cereals. Large quantities of flour are not sold in the form in which they come from the mill but
are utilized as blended and prepared flours for restaurants, cafeterias, and schools and as
all-purpose flours for the private household.
Industrial uses of wheat include the manufacture of malt, potable spirits, starch, gluten,
pastes, and core binders. Because of the relatively high price, wheat malt is used little in
the brewing and distilling industries. It is used mainly by the flour milling industry to increase
the alpha-amylase activity of high-grade flours. In the USA, small quantities of wheat flour
(mainly low-grade clears) are used to manufacture wheat starch as a by-product of viable
(functionally in bread making) gluten. The gluten is used to supplement flour proteins in
specialty-baked goods (hamburger buns, hot-dog buns, hearth-type breads, specialty
breads, etc) and as a raw material for the manufacture of monosodium glutamate, which
is used to accentuate the flavors of foods. Some low-grade flours are used in the
manufacture of pastes for bookbinding and paper hanging, in the manufacture of plywood
adhesives, and in iron foundries as a core binder in the preparation of molds for castings. In
Australia, the starch is a by-product of wheat gluten manufacture. Low-grade flours are also
used in Australia as an adjunct in brewing (as a source of fermentable sugars). The high
yields of wheat in western Europe (compared to those of corn) make attractive production of
starch and gluten, provided both products can be marketed economically.
WHEAT AND FLOUR QUALITY
In wheat and flour technology, the term quality denotes the suitability of the material for some
particular end use. It has no reference to nutritional attributes. Thus, the high-protein hard
wheat flour is of good bread making quality but is inferior to soft wheat flours for
chemically leavened products such as biscuits, cakes, and pastry.
The miller desires wheat that mills easily and gives a high flour yield. Wheat kernels should
be plump and uniformly large for ready separation of foreign materials without undue loss of
millable wheat. The wheat should produce a high yield of flour with maximum and clean
separation from the bran and germ without excessive consumption of power. Since the
endosperm is denser than the bran and the germ, high-density wheats produce more flour. In
production of bread flours, the reduction in protein content from wheat to flour should be
minimum (not above 1%). The test weight is affected by kernel shape, moisture content,
wetting and subsequent drying, and even handling, because these characteristics and
operations affect the grain packing. Weathering lowers
the test weight by swelling kernels, but the proportion of the endosperm remains the same.
Some environmental factors influence the ease of milling. Bran of weathered and frosted
wheats tends to pulverize, and it is difficult to secure clean separation of flour from bran.
ROLLER MILLING
e-- [email protected] Page 17 of 162
their reaction products are colored. Peroxidases and catalase are classed as
hydroperoxidases that catalyze the oxidation of certain aromatic amines and phenols by
hydrogen peroxide; they are also more active in bran than in the endosperm.
Wheat-Processing, Milling
Over two-thirds of the annual harvest of wheat is processed for food. The limited use for
industrial purposes is due mainly to its high price in relation to other cereal grains. The main
use of wheat for food is the manufacture of flour for making bread, biscuits, pastry products,
and semolina and farina for alimentary pastes. A small portion is converted into breakfast
cereals. Large quantities of flour are not sold in the form in which they come from the mill but
are utilized as blended and prepared flours for restaurants, cafeterias, and schools and as
all-purpose flours for the private household.
Industrial uses of wheat include the manufacture of malt, potable spirits, starch, gluten,
pastes, and core binders. Because of the relatively high price, wheat malt is used little in
the brewing and distilling industries. It is used mainly by the flour milling industry to increase
the alpha-amylase activity of high-grade flours. In the USA, small quantities of wheat flour
(mainly low-grade clears) are used to manufacture wheat starch as a by-product of viable
(functionally in bread making) gluten. The gluten is used to supplement flour proteins in
specialty-baked goods (hamburger buns, hot-dog buns, hearth-type breads, specialty
breads, etc) and as a raw material for the manufacture of monosodium glutamate, which
is used to accentuate the flavors of foods. Some low-grade flours are used in the
manufacture of pastes for bookbinding and paper hanging, in the manufacture of plywood
adhesives, and in iron foundries as a core binder in the preparation of molds for castings. In
Australia, the starch is a by-product of wheat gluten manufacture. Low-grade flours are also
used in Australia as an adjunct in brewing (as a source of fermentable sugars). The high
yields of wheat in western Europe (compared to those of corn) make attractive production of
starch and gluten, provided both products can be marketed economically.
WHEAT AND FLOUR QUALITY
In wheat and flour technology, the term quality denotes the suitability of the material for some
particular end use. It has no reference to nutritional attributes. Thus, the high-protein hard
wheat flour is of good bread making quality but is inferior to soft wheat flours for
chemically leavened products such as biscuits, cakes, and pastry.
The miller desires wheat that mills easily and gives a high flour yield. Wheat kernels should
be plump and uniformly large for ready separation of foreign materials without undue loss of
millable wheat. The wheat should produce a high yield of flour with maximum and clean
separation from the bran and germ without excessive consumption of power. Since the
endosperm is denser than the bran and the germ, high-density wheats produce more flour. In
production of bread flours, the reduction in protein content from wheat to flour should be
minimum (not above 1%). The test weight is affected by kernel shape, moisture content,
wetting and subsequent drying, and even handling, because these characteristics and
operations affect the grain packing. Weathering lowers
the test weight by swelling kernels, but the proportion of the endosperm remains the same.
Some environmental factors influence the ease of milling. Bran of weathered and frosted
wheats tends to pulverize, and it is difficult to secure clean separation of flour from bran.
ROLLER MILLING
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 18 of 162
Milling grain as food for man has been traced back more than 8,000 years. Flour milling has
advanced from a primitive and laborious household task to a vast and sophisticated, to a
large extent automated industry. In the production of white flour, the objective is to separate,
the starchy endosperm of the grain from the bran and germ. The separated endosperm is
pulverized. A partial separation of the starchy endosperm is possible because its physical
properties differ from those of the fibrous pericarp and oily germ. Bran is tough because of its
high fiber content, but the starchy endosperm is friable. The germ, because of its high oil
content, flakes when passed between smooth rolls. In addition, the particles from various
parts of the wheat kernel differ in density. This makes possible their separation by using air
currents.
The differences in friability of the bran and the starchy endosperm are enhanced by wheat
conditioning, which involves adding water before wheat is actually milled. The addition of
water toughens the bran and mellows the endosperm. The actual milling process comprises
a gradual reduction in particle size, first between corrugated break rolls and later between
smooth reduction rolls. The separation is empirical and not quantitative. The milling process
results in the production of many streams of flour and offals that can be combined in different
ways to produce different grades of flour. Still, the offals contain some of the starchy
endosperm particles, and some of the flour streams have little bran and germ particles.
Selection and Blending
The miller must produce a flour of definite characteristics and meet certain specifications for
a particular market. The most critical requirement is maintaining a uniform product from a
product (wheat) that may show a wide range of characteristics and composition.
Consequently, selection of wheats and milling according to quality for proper blending are
essential phases of modern milling. An adequate supply of wheat, binned according to
quality characteristics, makes it possible to build a uniform mix to meet some of the most
stringent specifications. The availability of rapid, nondestructive, near-infrared reflectance
instruments has made this task substantially easier.
Cleaning
Wheat received in the mill contains many impurities. Special machines are available to
remove those impurities. Preliminary cleaning involves the use of sieves, air blasts, and disc
separators. This is followed by dry scouring in which the wheat is forced against a perforated
iron casting by beaters fixed to a rapidly revolving drum. This treatment removes foreign
materials in the crease of the kernel and in the brush hairs. Some mills are equipped with
washers in which the wheat is scrubbed under a flowing stream of water. The washed wheat
is then passed through a "whizzer" (centrifuge), which removes free water. In practice, little
wheat is washed today, because the process is relatively ineffective, may actually increase
microbial populations, and creates problems of disposing large amounts of polluted water
with a high biological oxygen demand (BOD).
Conditioning
In this process water is added and allowed to stand for up to 24 hours to secure maximum
toughening of the bran with optimum mellowing of the starchy endosperm. The quantity of
water and the conditioning time are varied with different wheats to bring them to the optimum
conditioning for milling. The quantity of added water increases with decreasing moisture
content of the wheat, with increasing vitreousness, and with increasing plumpness.
Generally, hard wheats are tempered to 15-16% moisture and soft wheats to 14-15%
moisture. In the customary conditioning, the wheat is scoured again, after it has been held in
e-- [email protected] Page 18 of 162
Milling grain as food for man has been traced back more than 8,000 years. Flour milling has
advanced from a primitive and laborious household task to a vast and sophisticated, to a
large extent automated industry. In the production of white flour, the objective is to separate,
the starchy endosperm of the grain from the bran and germ. The separated endosperm is
pulverized. A partial separation of the starchy endosperm is possible because its physical
properties differ from those of the fibrous pericarp and oily germ. Bran is tough because of its
high fiber content, but the starchy endosperm is friable. The germ, because of its high oil
content, flakes when passed between smooth rolls. In addition, the particles from various
parts of the wheat kernel differ in density. This makes possible their separation by using air
currents.
The differences in friability of the bran and the starchy endosperm are enhanced by wheat
conditioning, which involves adding water before wheat is actually milled. The addition of
water toughens the bran and mellows the endosperm. The actual milling process comprises
a gradual reduction in particle size, first between corrugated break rolls and later between
smooth reduction rolls. The separation is empirical and not quantitative. The milling process
results in the production of many streams of flour and offals that can be combined in different
ways to produce different grades of flour. Still, the offals contain some of the starchy
endosperm particles, and some of the flour streams have little bran and germ particles.
Selection and Blending
The miller must produce a flour of definite characteristics and meet certain specifications for
a particular market. The most critical requirement is maintaining a uniform product from a
product (wheat) that may show a wide range of characteristics and composition.
Consequently, selection of wheats and milling according to quality for proper blending are
essential phases of modern milling. An adequate supply of wheat, binned according to
quality characteristics, makes it possible to build a uniform mix to meet some of the most
stringent specifications. The availability of rapid, nondestructive, near-infrared reflectance
instruments has made this task substantially easier.
Cleaning
Wheat received in the mill contains many impurities. Special machines are available to
remove those impurities. Preliminary cleaning involves the use of sieves, air blasts, and disc
separators. This is followed by dry scouring in which the wheat is forced against a perforated
iron casting by beaters fixed to a rapidly revolving drum. This treatment removes foreign
materials in the crease of the kernel and in the brush hairs. Some mills are equipped with
washers in which the wheat is scrubbed under a flowing stream of water. The washed wheat
is then passed through a "whizzer" (centrifuge), which removes free water. In practice, little
wheat is washed today, because the process is relatively ineffective, may actually increase
microbial populations, and creates problems of disposing large amounts of polluted water
with a high biological oxygen demand (BOD).
Conditioning
In this process water is added and allowed to stand for up to 24 hours to secure maximum
toughening of the bran with optimum mellowing of the starchy endosperm. The quantity of
water and the conditioning time are varied with different wheats to bring them to the optimum
conditioning for milling. The quantity of added water increases with decreasing moisture
content of the wheat, with increasing vitreousness, and with increasing plumpness.
Generally, hard wheats are tempered to 15-16% moisture and soft wheats to 14-15%
moisture. In the customary conditioning, the wheat is scoured again, after it has been held in
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 19 of 162
the tempering bins for several hours. A second small addition of 0.5% water is made about
20-60 minutes before the wheat goes to the rolls.
Breaking
The first part of the grinding process is carried out on corrugated rolls (break rolls), usually
24-30 inches long and 9 inches in diameter. Each stand has two pairs of rolls, which turn in
opposite directions at a differential speed of about 2.5: 1. In the first break rolls there are
usually 10-12 corrugations per inch. This number increases to 26-28 corrugations on the fifth
break roll. The corrugations run the length of the roll with a spiral cut, which is augmented
with an increase in the number of corrugations. As the rolls turn rapidly toward each other,
the edges of the corrugations of the fast roll cut across those of the slow roll, producing a
shearing and crushing action on the wheat, which falls in a rapid stream between them. The
first break rolls are spaced so that the wheat is crushed lightly and only a small quantity of
white flour is produced. After sieving, the coarsest material is conveyed to the second break
rolls. The second break rolls are set a little closer together than the first break rolls so that
the material is crushed finer and more endosperm particles are released. This process of
grinding and sifting is repeated up to six times. The material going to each succeeding break
contains less and less endosperm. After the last break, the largest fragments consist of
flakes of the wheat pericarp. They are passed through a wheat bran duster, which removes a
small quantity of low-grade flour.
Sieving
After each grinding step, the crushed material called stock or chop, is conveyed, to a sifter,
which is a large box fitted with a series of sloping sieves. The break sifters have a relatively
coarse wire sieve at the top and progressively'-finer silk sieves below, and end with a fine
flour silk at the bottom. The sifter is given a gyratory motion so that the finer stock particles
pass through the sieves from the head (top) to the tail (bottom). Particles that are too coarse
to pass through a particular sieve tail over it and are removed from the sifter box. The
process results in separation of three classes of material:, (1) coarse fragments, which are
fed to the next break until only bran remains; (2) flour, or fine particles, which pass through
the finest (flour) sieve; and (3) intermediate granular particles, which are called middlings.
Purification
The middlings consist of fragments of endosperm, small pieces of bran, and the released
embryos. Several sizes are separated from each of the break stocks; individual streams of
similar size and degree of refinement result from the sieving of several break stocks and are
combined. Subsequently, the bran-rich material is removed from the middlings. This is
accomplished in purifiers. Purifiers also produce a further classification of middlings
according to size and thereby complete the work of the sifters. In the purifier, the shallow
stream of middlings travels over a large sieve, while shaken rapidly backward and forward.
The sieve consists of a tightly stretched bolting silk or grits gauze, which becomes
progressively coarser from the head to the tail end of the purifier. An upward air current
through the sieve draws off light material to dust collectors and holds bran particles on the
surface of the moving middlings so that they drift over to the tail of the sieve.
Reduction
The purified and classified middlings are gradually pulverized to flour between smooth
reduction rolls, which revolve at a differential of about 1.5: 1. The space between the rolls is
adjusted to the granulation of the middlings. The endosperm fragments passing through the
e-- [email protected] Page 19 of 162
the tempering bins for several hours. A second small addition of 0.5% water is made about
20-60 minutes before the wheat goes to the rolls.
Breaking
The first part of the grinding process is carried out on corrugated rolls (break rolls), usually
24-30 inches long and 9 inches in diameter. Each stand has two pairs of rolls, which turn in
opposite directions at a differential speed of about 2.5: 1. In the first break rolls there are
usually 10-12 corrugations per inch. This number increases to 26-28 corrugations on the fifth
break roll. The corrugations run the length of the roll with a spiral cut, which is augmented
with an increase in the number of corrugations. As the rolls turn rapidly toward each other,
the edges of the corrugations of the fast roll cut across those of the slow roll, producing a
shearing and crushing action on the wheat, which falls in a rapid stream between them. The
first break rolls are spaced so that the wheat is crushed lightly and only a small quantity of
white flour is produced. After sieving, the coarsest material is conveyed to the second break
rolls. The second break rolls are set a little closer together than the first break rolls so that
the material is crushed finer and more endosperm particles are released. This process of
grinding and sifting is repeated up to six times. The material going to each succeeding break
contains less and less endosperm. After the last break, the largest fragments consist of
flakes of the wheat pericarp. They are passed through a wheat bran duster, which removes a
small quantity of low-grade flour.
Sieving
After each grinding step, the crushed material called stock or chop, is conveyed, to a sifter,
which is a large box fitted with a series of sloping sieves. The break sifters have a relatively
coarse wire sieve at the top and progressively'-finer silk sieves below, and end with a fine
flour silk at the bottom. The sifter is given a gyratory motion so that the finer stock particles
pass through the sieves from the head (top) to the tail (bottom). Particles that are too coarse
to pass through a particular sieve tail over it and are removed from the sifter box. The
process results in separation of three classes of material:, (1) coarse fragments, which are
fed to the next break until only bran remains; (2) flour, or fine particles, which pass through
the finest (flour) sieve; and (3) intermediate granular particles, which are called middlings.
Purification
The middlings consist of fragments of endosperm, small pieces of bran, and the released
embryos. Several sizes are separated from each of the break stocks; individual streams of
similar size and degree of refinement result from the sieving of several break stocks and are
combined. Subsequently, the bran-rich material is removed from the middlings. This is
accomplished in purifiers. Purifiers also produce a further classification of middlings
according to size and thereby complete the work of the sifters. In the purifier, the shallow
stream of middlings travels over a large sieve, while shaken rapidly backward and forward.
The sieve consists of a tightly stretched bolting silk or grits gauze, which becomes
progressively coarser from the head to the tail end of the purifier. An upward air current
through the sieve draws off light material to dust collectors and holds bran particles on the
surface of the moving middlings so that they drift over to the tail of the sieve.
Reduction
The purified and classified middlings are gradually pulverized to flour between smooth
reduction rolls, which revolve at a differential of about 1.5: 1. The space between the rolls is
adjusted to the granulation of the middlings. The endosperm fragments passing through the
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 20 of 162
rolls are reduced to finer middlings and flour. The remaining fibrous fragments of bran are
flaked or flattened. After each reduction step, the resulting stock is sifted. Most of the bran
fragments are removed on the top sieve while the flour passes through the finest bottom
sieve. The remaining middlings are separated according to size, are moved to their
respective purifiers, and are then passed to other reduction rolls. These steps are repeated
until most of the endosperm has been converted to flour and most of the bran has been
removed as offal b the reduction sifters. What remains is a mixture of fine middlings and bran
with a little germ; this is called feed middlings. Impact mills have been used in reduction
grinding, especially with soft wheats. Close grinding using clean middlings on reduction rolls,
followed by a pin mill or detacher, increases the yield of flour from a reduction step. This
process has been used more for soft than for hard wheats.
The embryos are largely released by the break 'system and appear as lemon-yellow particles
in some of the coarser middling streams. These streams are called sizings. The embryos are
flattened in reduction of the sizings and are separated as flakes during sieving. Germ may be
separated also without reduction of the sizings by gravity and regular air currents. Previously,
the entire germ was mixed with the shorts as feed. Some special uses of germ in foods and
as a source of pharmaceuticals have been developed.
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rolls are reduced to finer middlings and flour. The remaining fibrous fragments of bran are
flaked or flattened. After each reduction step, the resulting stock is sifted. Most of the bran
fragments are removed on the top sieve while the flour passes through the finest bottom
sieve. The remaining middlings are separated according to size, are moved to their
respective purifiers, and are then passed to other reduction rolls. These steps are repeated
until most of the endosperm has been converted to flour and most of the bran has been
removed as offal b the reduction sifters. What remains is a mixture of fine middlings and bran
with a little germ; this is called feed middlings. Impact mills have been used in reduction
grinding, especially with soft wheats. Close grinding using clean middlings on reduction rolls,
followed by a pin mill or detacher, increases the yield of flour from a reduction step. This
process has been used more for soft than for hard wheats.
The embryos are largely released by the break 'system and appear as lemon-yellow particles
in some of the coarser middling streams. These streams are called sizings. The embryos are
flattened in reduction of the sizings and are separated as flakes during sieving. Germ may be
separated also without reduction of the sizings by gravity and regular air currents. Previously,
the entire germ was mixed with the shorts as feed. Some special uses of germ in foods and
as a source of pharmaceuticals have been developed.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 21 of 162
e-- [email protected] Page 21 of 162
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 22 of 162
How Wheat Becomes Flour
(A simplified diagram)
ELEVATOR - storage
and care of wheat.
PRODUCT CONTROL -
chemists inspect and
classify wheat, blending
is often done at this
point
MAGNETIC
SEPARATOR - iron or
steel articles stay here.
SEPARATOR -
reciprocating screens
remove stones, sticks
and other coarse and
fine materials.
ASPIRATOR - air
currents remove lighter
impurities
DE-STONER
DISC SEPARATOR -
barley, oats, cockle and
other foreign materials
are removed.
e-- [email protected] Page 22 of 162
How Wheat Becomes Flour
(A simplified diagram)
ELEVATOR - storage
and care of wheat.
PRODUCT CONTROL -
chemists inspect and
classify wheat, blending
is often done at this
point
MAGNETIC
SEPARATOR - iron or
steel articles stay here.
SEPARATOR -
reciprocating screens
remove stones, sticks
and other coarse and
fine materials.
ASPIRATOR - air
currents remove lighter
impurities
DE-STONER
DISC SEPARATOR -
barley, oats, cockle and
other foreign materials
are removed.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 23 of 162
SCOURER - beaters in
screen cylinder scour
off inpurities and
roughage.
TEMPERING MIXER -
moistens wheat
evenly.
TEMPERING - water
toughens outer bran
coats for easier
separation- softens or
mellows endosperm.
BLENDING - types of
wheat are blended to
make specific flours.
IMPACT SCOURER -
impact machine breaks
and removes unsound
wheat.
FIRST BREAK -
corrugated rolls break
wheat into coarse
particles.
e-- [email protected] Page 23 of 162
SCOURER - beaters in
screen cylinder scour
off inpurities and
roughage.
TEMPERING MIXER -
moistens wheat
evenly.
TEMPERING - water
toughens outer bran
coats for easier
separation- softens or
mellows endosperm.
BLENDING - types of
wheat are blended to
make specific flours.
IMPACT SCOURER -
impact machine breaks
and removes unsound
wheat.
FIRST BREAK -
corrugated rolls break
wheat into coarse
particles.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 24 of 162
broken wheat is
sifted through
successive screens
of increasing
fineness.
air currents and
sieves separate
bran and classify
particles (or
middlings).
REDUCING
ROLLS - smooth
rolls reduce
middlings into
flour.
A series of
purifiers, reducing
rolls and sifter
repeat the
process.
BLEACHING -
flour is matured
and color
neutralized.
from the sifter . . .
from the sifter . . .
from bulk storage . . .
e-- [email protected] Page 24 of 162
broken wheat is
sifted through
successive screens
of increasing
fineness.
air currents and
sieves separate
bran and classify
particles (or
middlings).
REDUCING
ROLLS - smooth
rolls reduce
middlings into
flour.
A series of
purifiers, reducing
rolls and sifter
repeat the
process.
BLEACHING -
flour is matured
and color
neutralized.
from the sifter . . .
from the sifter . . .
from bulk storage . . .
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 25 of 162
Flour Grades
Each grinding and sieving operation produces flour. In addition to the various break and
middlings flours, a small quantity of flour is obtained from dust collectors and bran and shorts
dusters. With each successive reduction, the flour contains more pulverized bran and germ.
The flour from the last reduction, called "red dog," is dark in color and high in components
originating from the bran and germ, such as ash, fiber, pentosans, lipids, sugars, and
vitamins. Such flour bakes into dark-colored, coarse-grained bread but is mostly sold as feed
flour.
In a large mill there may be 30 or more streams that vary widely in composition. If all the
streams are combined, the product is called straight flour. A straight flour of 100%, however,
does not mean whole-wheat flour. It means, generally, 75% flour; because wheat milling
yields about 75% white flour and about 25% feed products. Frequently, the more-highly
refined (white) streams are taken off and sold separately as patent flours; the remaining
streams, which contain some bran and germ, are called clear flours. A diagram of flours and
milled feed products is given in Figure 8-2. Some clear flours are dark in color and low in
bread-making quality. Some of the better, lighter, clear flours are used in blends with rye
and/or whole wheat fl6urs in the production of specialty breads. The darker grades of clear
flours are used in the manufacture of gluten, starch, monosodium glutamate, and pet foods.
Yields of Mill Products
The plump wheat grain consists of about 8% endosperm, 14.5% bran, and 2.5% germ.
These three structures are not separated completely, however, in the milling process. The
yield of total flour ranges from 72% to 75%, and the flour contains little bran and germ. In
ordinary milling processes only about 0.25% of the germ is recovered. Bran range from 12%
to 16% of the wheat milled. The remaining by-products are shorts. The low-grade flour and
feed middlings may be sold separately as feed by-products. The objective of efficient milling
is to maximize the monetary value of the total mill products, generally by increasing the yield
of flours.
Flour Fractionation
Wheat flour produced by conventional roller milling contains particles of different sizes (from
1 to 150 μm), such as large endosperm chunks, small particles of free protein, free starch
granules, and small chunks of protein attached to starch granules. The flour can be ground,
pin milled to avoid excessive starch damage, to fine particles in which the protein is freed
from the starch. The pin-milled flour is then passed through an air classifier A fine fraction,
made up of particles about 40 μm and smaller, is removed and passed through a second air
classifier. Particles of about 20 μm and smaller are separated; they comprise about 10% of
the original flour and contain up to about twice the protein of the unfractionated flour. This
e-- [email protected] Page 25 of 162
Flour Grades
Each grinding and sieving operation produces flour. In addition to the various break and
middlings flours, a small quantity of flour is obtained from dust collectors and bran and shorts
dusters. With each successive reduction, the flour contains more pulverized bran and germ.
The flour from the last reduction, called "red dog," is dark in color and high in components
originating from the bran and germ, such as ash, fiber, pentosans, lipids, sugars, and
vitamins. Such flour bakes into dark-colored, coarse-grained bread but is mostly sold as feed
flour.
In a large mill there may be 30 or more streams that vary widely in composition. If all the
streams are combined, the product is called straight flour. A straight flour of 100%, however,
does not mean whole-wheat flour. It means, generally, 75% flour; because wheat milling
yields about 75% white flour and about 25% feed products. Frequently, the more-highly
refined (white) streams are taken off and sold separately as patent flours; the remaining
streams, which contain some bran and germ, are called clear flours. A diagram of flours and
milled feed products is given in Figure 8-2. Some clear flours are dark in color and low in
bread-making quality. Some of the better, lighter, clear flours are used in blends with rye
and/or whole wheat fl6urs in the production of specialty breads. The darker grades of clear
flours are used in the manufacture of gluten, starch, monosodium glutamate, and pet foods.
Yields of Mill Products
The plump wheat grain consists of about 8% endosperm, 14.5% bran, and 2.5% germ.
These three structures are not separated completely, however, in the milling process. The
yield of total flour ranges from 72% to 75%, and the flour contains little bran and germ. In
ordinary milling processes only about 0.25% of the germ is recovered. Bran range from 12%
to 16% of the wheat milled. The remaining by-products are shorts. The low-grade flour and
feed middlings may be sold separately as feed by-products. The objective of efficient milling
is to maximize the monetary value of the total mill products, generally by increasing the yield
of flours.
Flour Fractionation
Wheat flour produced by conventional roller milling contains particles of different sizes (from
1 to 150 μm), such as large endosperm chunks, small particles of free protein, free starch
granules, and small chunks of protein attached to starch granules. The flour can be ground,
pin milled to avoid excessive starch damage, to fine particles in which the protein is freed
from the starch. The pin-milled flour is then passed through an air classifier A fine fraction,
made up of particles about 40 μm and smaller, is removed and passed through a second air
classifier. Particles of about 20 μm and smaller are separated; they comprise about 10% of
the original flour and contain up to about twice the protein of the unfractionated flour. This
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
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high-protein flour is used to fortify low-protein bread flours or for enrichment in the production
of specialty baked goods. A comparable fraction containing about half the protein content of
the unfractionated flour is also obtainable.
Air classification has created considerable interest in the milling industry. Its advantages are
numerous, such as manufacture of uniform flours from varying wheats; increase of protein
content of bread flours and decrease of protein content in cake and cookie flours; controlled
particle size and chemical composition and production of special flours for specific uses. A
number of equipment and process patents on fine grinding and separation have been issued.
The technology of the process is well known, yet its benefits and potential have not been fully
utilized mainly because of the availability of low and high-protein wheats and the high-energy
cost involved in air classification. In recent years there has been interest in air-classified low-
protein fractions as a replacement of chlorinated wheat flour in high-ratio cake production.
Soft Wheat Milling
Soft wheats are milled by the method of gradual reduction, similar to the method for milling
hard bread wheats. Patent flours containing 7-9% protein, milled from soft red winter wheats,
are especially suitable for chemically leavened biscuits and hot breads. Special mixtures of
soft wheats are used to make cake flours for use in cookie and cake making; such flours
usually contain 8% protein or less and are milled to very short patents (about 30%).
Treatment with heavy dosages of chlorine lower the pH to about 5.1-5.3, weaken the gluten,
and facilitate the production of short pastry. Cake flours are sieved through silk of finer mesh
than that used for biscuit or bread flours.
Durum Wheat Milling
In durum milling, the objective is the production of a maximum yield of highly purified
semolina. Although the same sequence of operations is employed in the production of flour
and semolina, the milling systems differ in design. In semolina manufacture, the cleaning and
purifying systems must remove impurities and the mill offals. Durum wheat milling involves
cleaning and conditioning of the grain, light grinding, and extensive purification. The cleaning,
breaking, sizing, and purifying systems are much more elaborate and extensive than in
flourmills. On the other hand, the reduction system is shorter in durum mills, because the
primary product is removed and finished in the granular condition. For maximum yield of
large endosperm particles, break rolls with U-cut corrugations are employed. The break
system is extensive to permit lighter and more gradual grinding than in flourmills. Durum
wheat of good milling quality normally yields about 62% semolina, 16% clear flour, and 22%
feeds. Particle size distribution and granulation of semolina are highly important in the
production of macaroni.
Flour Bleaching and Maturing
Bleaching of flour was introduced as early as 1879 in Britain and around 1900 in America. In
the earliest days flour was treated with nitrogen peroxide. Subsequently other methods came
into use to make the flour whiter and simultaneously improve the dough handling and bread
characteristics. The treated flour possesses baking properties similar to those of flour that
has been stored and naturally aged. Today, much bread and practically all cake flours in the
United States are bleached. In addition, maturing agents are used to obtain maximum baking
performance. Flour improvers are used in Great Britain, Canada and many other countries.
In West Germany only ascorbic acid may be used legally as a flour improver. In still other
countries no flour improver is allowed. Agents that have maturing action but little or no
bleaching action include bromates, iodates, peroxysulfates, peroxyborates, calcium peroxide,
and ascorbic acid (which is enzymatically converted to dehydroascorbic acid, an oxidizing
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high-protein flour is used to fortify low-protein bread flours or for enrichment in the production
of specialty baked goods. A comparable fraction containing about half the protein content of
the unfractionated flour is also obtainable.
Air classification has created considerable interest in the milling industry. Its advantages are
numerous, such as manufacture of uniform flours from varying wheats; increase of protein
content of bread flours and decrease of protein content in cake and cookie flours; controlled
particle size and chemical composition and production of special flours for specific uses. A
number of equipment and process patents on fine grinding and separation have been issued.
The technology of the process is well known, yet its benefits and potential have not been fully
utilized mainly because of the availability of low and high-protein wheats and the high-energy
cost involved in air classification. In recent years there has been interest in air-classified low-
protein fractions as a replacement of chlorinated wheat flour in high-ratio cake production.
Soft Wheat Milling
Soft wheats are milled by the method of gradual reduction, similar to the method for milling
hard bread wheats. Patent flours containing 7-9% protein, milled from soft red winter wheats,
are especially suitable for chemically leavened biscuits and hot breads. Special mixtures of
soft wheats are used to make cake flours for use in cookie and cake making; such flours
usually contain 8% protein or less and are milled to very short patents (about 30%).
Treatment with heavy dosages of chlorine lower the pH to about 5.1-5.3, weaken the gluten,
and facilitate the production of short pastry. Cake flours are sieved through silk of finer mesh
than that used for biscuit or bread flours.
Durum Wheat Milling
In durum milling, the objective is the production of a maximum yield of highly purified
semolina. Although the same sequence of operations is employed in the production of flour
and semolina, the milling systems differ in design. In semolina manufacture, the cleaning and
purifying systems must remove impurities and the mill offals. Durum wheat milling involves
cleaning and conditioning of the grain, light grinding, and extensive purification. The cleaning,
breaking, sizing, and purifying systems are much more elaborate and extensive than in
flourmills. On the other hand, the reduction system is shorter in durum mills, because the
primary product is removed and finished in the granular condition. For maximum yield of
large endosperm particles, break rolls with U-cut corrugations are employed. The break
system is extensive to permit lighter and more gradual grinding than in flourmills. Durum
wheat of good milling quality normally yields about 62% semolina, 16% clear flour, and 22%
feeds. Particle size distribution and granulation of semolina are highly important in the
production of macaroni.
Flour Bleaching and Maturing
Bleaching of flour was introduced as early as 1879 in Britain and around 1900 in America. In
the earliest days flour was treated with nitrogen peroxide. Subsequently other methods came
into use to make the flour whiter and simultaneously improve the dough handling and bread
characteristics. The treated flour possesses baking properties similar to those of flour that
has been stored and naturally aged. Today, much bread and practically all cake flours in the
United States are bleached. In addition, maturing agents are used to obtain maximum baking
performance. Flour improvers are used in Great Britain, Canada and many other countries.
In West Germany only ascorbic acid may be used legally as a flour improver. In still other
countries no flour improver is allowed. Agents that have maturing action but little or no
bleaching action include bromates, iodates, peroxysulfates, peroxyborates, calcium peroxide,
and ascorbic acid (which is enzymatically converted to dehydroascorbic acid, an oxidizing
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 27 of 162
agent). Agents that have both bleaching and maturing effect include oxygen, ozone, chlorine,
and chlorine dioxide. The improvers azodicarbonamide and acetone peroxide have been
approved by the Food and Drug Administration for inclusion with the standards of identity for
flour as bleaching and maturing agents. Acetone peroxide performs a dual function of
bleaching and maturing. Azodicarbonamide H 2NCON=NCONH 2 is reduced to
hydrazodicarbonamide (biurea), H2NCONHNHCONH 2. It has maturing action only. Benzoyl
peroxide is added primarily as a bleaching agent. Additional agents, used less commonly for
bleaching, include nitrogen peroxide, fatty acid peroxides, and certain preparations (e.g.,
from untreated soy flour) containing the enzyme lipoxygenase.
Quantitative requirement for oxidation of flours depends on several factors. Generally, as the
protein content increases, the requirement for oxidants increases. Mixing time and oxidation
levels compensate each other to some extent, even though they are not completely
interchange- able. As the degree of milling refinement or flour grade is lowered, oxidation
requirements increase, because protein sulfhydryl groups susceptible to oxidation are found
in higher concentrations in the aleurone layer and the germ than in the starchy endosperm.
Low-grade flours have more of those tissues than highly refined flours.
It may contain a maximum of 200 ppm ascorbic acid and optimum amounts of the following
bleaching and/or oxidizing (aging) agents (alone or combinations): oxides of nitrogen,
chlorine, nitrosyl chloride, chlorine dioxide, benzoyl peroxide (with carrier), acetone
peroxides, and up to 45 ppm azodicarbonamide. Up to 50 ppm potassium bromate may be
added to flours whose baking qualities are improved by such additions,
Enriched flour contains (mg/lb) 2.9 thiamine, 1.8 riboflavin, 24 niacin, and 13.0-16.5 iron. Its
total calcium content should not exceed 960 mg/lb, and it may contain up to 5% wheat germ
or partly defatted wheat germ.
Instantized flours are prepared by selective grinding or bolting, other milling procedures, or
by agglomerating procedures.
Phosphated flour contains 0.25-0.75% monocalcium phosphate.
Self-raising flour contains a mixture of sodium bicarbonate and one or more acid-reacting
substances added to a maximum level of 4.5 parts per 100 parts of flour to produce at least
0.5% of carbon dioxide.
Cracked wheat is produced by cracking,
Crushed wheat flour by crushing, and
Whole wheat flour by grinding cleaned wheat, other than durum and red durum, to meet
specified granulation requirements. The maximum of potassium bromate in whole-wheat
flour is 75 ppm.
The ash content of farina may not exceed 0.6% and of semolina 0.92%, on a moisture-free
basis, for both. Farina may be enriched to contain (per pound) 2.0-2.5 mg thiamine, 1.2-1.5
mg riboflavin, 16.0-20.0 mg niacin, at least 13.0 mg iron, and 500 mg of the optional
ingredient calcium.
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agent). Agents that have both bleaching and maturing effect include oxygen, ozone, chlorine,
and chlorine dioxide. The improvers azodicarbonamide and acetone peroxide have been
approved by the Food and Drug Administration for inclusion with the standards of identity for
flour as bleaching and maturing agents. Acetone peroxide performs a dual function of
bleaching and maturing. Azodicarbonamide H 2NCON=NCONH 2 is reduced to
hydrazodicarbonamide (biurea), H2NCONHNHCONH 2. It has maturing action only. Benzoyl
peroxide is added primarily as a bleaching agent. Additional agents, used less commonly for
bleaching, include nitrogen peroxide, fatty acid peroxides, and certain preparations (e.g.,
from untreated soy flour) containing the enzyme lipoxygenase.
Quantitative requirement for oxidation of flours depends on several factors. Generally, as the
protein content increases, the requirement for oxidants increases. Mixing time and oxidation
levels compensate each other to some extent, even though they are not completely
interchange- able. As the degree of milling refinement or flour grade is lowered, oxidation
requirements increase, because protein sulfhydryl groups susceptible to oxidation are found
in higher concentrations in the aleurone layer and the germ than in the starchy endosperm.
Low-grade flours have more of those tissues than highly refined flours.
It may contain a maximum of 200 ppm ascorbic acid and optimum amounts of the following
bleaching and/or oxidizing (aging) agents (alone or combinations): oxides of nitrogen,
chlorine, nitrosyl chloride, chlorine dioxide, benzoyl peroxide (with carrier), acetone
peroxides, and up to 45 ppm azodicarbonamide. Up to 50 ppm potassium bromate may be
added to flours whose baking qualities are improved by such additions,
Enriched flour contains (mg/lb) 2.9 thiamine, 1.8 riboflavin, 24 niacin, and 13.0-16.5 iron. Its
total calcium content should not exceed 960 mg/lb, and it may contain up to 5% wheat germ
or partly defatted wheat germ.
Instantized flours are prepared by selective grinding or bolting, other milling procedures, or
by agglomerating procedures.
Phosphated flour contains 0.25-0.75% monocalcium phosphate.
Self-raising flour contains a mixture of sodium bicarbonate and one or more acid-reacting
substances added to a maximum level of 4.5 parts per 100 parts of flour to produce at least
0.5% of carbon dioxide.
Cracked wheat is produced by cracking,
Crushed wheat flour by crushing, and
Whole wheat flour by grinding cleaned wheat, other than durum and red durum, to meet
specified granulation requirements. The maximum of potassium bromate in whole-wheat
flour is 75 ppm.
The ash content of farina may not exceed 0.6% and of semolina 0.92%, on a moisture-free
basis, for both. Farina may be enriched to contain (per pound) 2.0-2.5 mg thiamine, 1.2-1.5
mg riboflavin, 16.0-20.0 mg niacin, at least 13.0 mg iron, and 500 mg of the optional
ingredient calcium.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 28 of 162
e-- [email protected] Page 28 of 162
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 29 of 162
Flour Types
Hard Wheat Flours
Top Patent
0.35 - 0.40% ash content: 11.0-12.0% protein
Uses: - Danishes, sweet doughs, yeast doughnuts
and smaller volume breads and buns.
First Baker's
0.50 - 0.55%. ash content: 13.0-13.8% protein
Uses: All purpose strong baker's flour, breads,
buns, soft rolls and puff pastry
First Clears
0.70-0.80% ash content: 15.5-17% protein
Uses: A dark very high protein flour used as a
base for rye bread production; poor color not a
factor in finished product.
Second Clears
Low grade flour, not used in food production.
Constitutes less than 5% of flour produced by a
mill.
Soft Wheat Flours
Cake Flour
0.36-0.40% ash content: 7.8 - 8.5% protein,
chlorinated to 4.5- 5.0 pH.
Uses: High-ratio cakes (cakes with a high amount
of sugar and liquid in proportion to flour), angel
food cakes and jelly rolls.
Pastry Flour
0.40-0.45% ash content/8.0-8.8% protein,
chlorinated to 5.0-5.5 pH, (also available
unchlorinated).
Uses: Cake, pastries and pies.
Cookie Flour
0.45-0.50% ash content: 9.0 - 10.5% protein
Uses: Cookies and blended flours. For large-scale
manufacturers, flour can be chlorinated to the
user's specifications.
Whole Wheat Flour
Various bran coat granulations produce coarse to
fine whole-wheat
Per 100 Parts of Dry Substance
Type & DenominationMaximum Moisture % Maximum Ash Maximum CelluloseMinimum Gluten
Flour Type 00 14.50 .50 NA 7
Flour Type 0 14.50 .65 .20 9
Flour Type 1 14.50 .80 .30 10
Flour Type 2 14.50 .95 .50 10
Flour -Wheat 14.50 1.40 - 1.60 1.6 10
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Flour Types
Hard Wheat Flours
Top Patent
0.35 - 0.40% ash content: 11.0-12.0% protein
Uses: - Danishes, sweet doughs, yeast doughnuts
and smaller volume breads and buns.
First Baker's
0.50 - 0.55%. ash content: 13.0-13.8% protein
Uses: All purpose strong baker's flour, breads,
buns, soft rolls and puff pastry
First Clears
0.70-0.80% ash content: 15.5-17% protein
Uses: A dark very high protein flour used as a
base for rye bread production; poor color not a
factor in finished product.
Second Clears
Low grade flour, not used in food production.
Constitutes less than 5% of flour produced by a
mill.
Soft Wheat Flours
Cake Flour
0.36-0.40% ash content: 7.8 - 8.5% protein,
chlorinated to 4.5- 5.0 pH.
Uses: High-ratio cakes (cakes with a high amount
of sugar and liquid in proportion to flour), angel
food cakes and jelly rolls.
Pastry Flour
0.40-0.45% ash content/8.0-8.8% protein,
chlorinated to 5.0-5.5 pH, (also available
unchlorinated).
Uses: Cake, pastries and pies.
Cookie Flour
0.45-0.50% ash content: 9.0 - 10.5% protein
Uses: Cookies and blended flours. For large-scale
manufacturers, flour can be chlorinated to the
user's specifications.
Whole Wheat Flour
Various bran coat granulations produce coarse to
fine whole-wheat
Per 100 Parts of Dry Substance
Type & DenominationMaximum Moisture % Maximum Ash Maximum CelluloseMinimum Gluten
Flour Type 00 14.50 .50 NA 7
Flour Type 0 14.50 .65 .20 9
Flour Type 1 14.50 .80 .30 10
Flour Type 2 14.50 .95 .50 10
Flour -Wheat 14.50 1.40 - 1.60 1.6 10
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
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RICE
Longitudinal cross section of rice
Rice is a covered cereal. In the threshed grain (or rough rice), the kernel is enclosed in a
tough siliceous, hull, which renders it unsuitable for human consumption. When this hull is
removed, the kernel or caryopsis, comprising the pericarp (outer bran) and the seed proper
(inner bran, endosperm, and germ), is known as brown rice. Brown rice is little in demand as
a food. It tends to become rancid and is subject to insect infestation. When brown rice is
subjected to further milling processes, the bran, aleurone layer, and germ are removed, and
the purified endosperms are marketed as white rice or polished rice, which is classified
according to size as head rice (at least three-fourths of the whole endosperm) and various
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RICE
Longitudinal cross section of rice
Rice is a covered cereal. In the threshed grain (or rough rice), the kernel is enclosed in a
tough siliceous, hull, which renders it unsuitable for human consumption. When this hull is
removed, the kernel or caryopsis, comprising the pericarp (outer bran) and the seed proper
(inner bran, endosperm, and germ), is known as brown rice. Brown rice is little in demand as
a food. It tends to become rancid and is subject to insect infestation. When brown rice is
subjected to further milling processes, the bran, aleurone layer, and germ are removed, and
the purified endosperms are marketed as white rice or polished rice, which is classified
according to size as head rice (at least three-fourths of the whole endosperm) and various
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
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classes of broken rice, known as second- hand, screenings, and brewers' rice, in decreasing
size.
Types of rice
There are about 20 varieties of rice grown commercially in the U.S. All can be classified as
long, medium or short grain. California grows short and medium grain varieties, while
Louisiana produces medium and long grain varieties. Long grain rice is predominantly grown
in Arkansas, Mississippi, Missouri and Texas, with some production of medium grain
varieties in each state.
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classes of broken rice, known as second- hand, screenings, and brewers' rice, in decreasing
size.
Types of rice
There are about 20 varieties of rice grown commercially in the U.S. All can be classified as
long, medium or short grain. California grows short and medium grain varieties, while
Louisiana produces medium and long grain varieties. Long grain rice is predominantly grown
in Arkansas, Mississippi, Missouri and Texas, with some production of medium grain
varieties in each state.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 32 of 162
Long Grain
Long and slender, these grains are 4 to 5 times as long as they are wide. Cooked grains
remain separate and fluffy. The perfect choice for side dish, main dish or salad recipes.
Medium Grain
Plump, but not round. When cooked, the grains are more moist and tender than long grain
rice. Ideal for dessert, casserole, bread and stir-fry recipes.
Short Grain
Almost round, the cooked grains tend to cling together when cooked. Great for stir-fry recipes
and puddings.
Forms of Rice
Brown Rice
Rice from which only the hull as been removed. When cooked, it has a slightly chewy texture
and nut-like flavor. This is a natural source of bran. It cooks in approximately 40-45 minutes.
Parboiled Rice
Unmilled rice is soaked, steamed and dried before milling. Nutrients stay within the grain and
surface starch is reduced, producing a cooked rice that is somewhat more firm in texture and
very separate when cooked. It cooks perfectly in approximately 20 minutes.
Regular-milled White Rice
This rice has been completely milled and polished, removing the bran layer. Vitamins and
minerals are added for enrichment. It takes about 15 minutes to cook.
MILLING
The objective of rice milling is to remove the hull, bran, and germ with minimum breakage of
the starchy endosperm (White, 1970). The rough rice, or paddy, is cleaned and conveyed to
shelling machines that loosen the hulls. Conventional shelters consist of two steel plates, 4 x
5 feet in diameter, mounted horizontally. The inner surfaces are coated with a mixture of
cement and carborundum. One plate is stationary and the other is rotated. As the plate
revolves, the pressure on the ends of the upturned grains disengages the hulls. The hulls are
removed by aspiration, and the remaining hulled and unhulled grains are separated in a
paddy machine that consists of a large box shaker fitted with vertical, smooth steel plates set
on a slight incline to form zigzag ducts. The plates and the shaking action cause the less
dense paddy grains to move upward while the heavier hulled grains move downward. Rough
rice may also be shelled with rubber rolls or with a rubber- belt operating against a ribbed
steel roll.
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Long Grain
Long and slender, these grains are 4 to 5 times as long as they are wide. Cooked grains
remain separate and fluffy. The perfect choice for side dish, main dish or salad recipes.
Medium Grain
Plump, but not round. When cooked, the grains are more moist and tender than long grain
rice. Ideal for dessert, casserole, bread and stir-fry recipes.
Short Grain
Almost round, the cooked grains tend to cling together when cooked. Great for stir-fry recipes
and puddings.
Forms of Rice
Brown Rice
Rice from which only the hull as been removed. When cooked, it has a slightly chewy texture
and nut-like flavor. This is a natural source of bran. It cooks in approximately 40-45 minutes.
Parboiled Rice
Unmilled rice is soaked, steamed and dried before milling. Nutrients stay within the grain and
surface starch is reduced, producing a cooked rice that is somewhat more firm in texture and
very separate when cooked. It cooks perfectly in approximately 20 minutes.
Regular-milled White Rice
This rice has been completely milled and polished, removing the bran layer. Vitamins and
minerals are added for enrichment. It takes about 15 minutes to cook.
MILLING
The objective of rice milling is to remove the hull, bran, and germ with minimum breakage of
the starchy endosperm (White, 1970). The rough rice, or paddy, is cleaned and conveyed to
shelling machines that loosen the hulls. Conventional shelters consist of two steel plates, 4 x
5 feet in diameter, mounted horizontally. The inner surfaces are coated with a mixture of
cement and carborundum. One plate is stationary and the other is rotated. As the plate
revolves, the pressure on the ends of the upturned grains disengages the hulls. The hulls are
removed by aspiration, and the remaining hulled and unhulled grains are separated in a
paddy machine that consists of a large box shaker fitted with vertical, smooth steel plates set
on a slight incline to form zigzag ducts. The plates and the shaking action cause the less
dense paddy grains to move upward while the heavier hulled grains move downward. Rough
rice may also be shelled with rubber rolls or with a rubber- belt operating against a ribbed
steel roll.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 33 of 162
Friction type rice mill
The process causes less mechanical damage and improves stability against rancidity. Hulled
rice is sent to machines that consist of grooved tapering cylinders that revolve rapidly in
stationary, uniformly perforated cylinders. The entire machine is filled with grain, and a blade
that protrudes between the upper and lower halves of the perforated cylinder regulates the
packing force. The outside bran layers and the germ are removed by the scouring action of
the rice grains moving against themselves near the surface or the perforated cylinder. After
passing through a succession of hullers, the rice is practically free from germ and outer bran.
Scouring is usually completed, by polishing in a brush machine. The polished rice contains
whole endosperms and broken particles of various sizes. Grading reels of disc separators
separates them.
The yield of white rice normally varies between 66% and 70%, based on the weight of rough
rice. As head rice is the most valuable product, its yield determines the milling quality of
rough rice. The price obtained for the various classes of broken rice decreases with size.
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Friction type rice mill
The process causes less mechanical damage and improves stability against rancidity. Hulled
rice is sent to machines that consist of grooved tapering cylinders that revolve rapidly in
stationary, uniformly perforated cylinders. The entire machine is filled with grain, and a blade
that protrudes between the upper and lower halves of the perforated cylinder regulates the
packing force. The outside bran layers and the germ are removed by the scouring action of
the rice grains moving against themselves near the surface or the perforated cylinder. After
passing through a succession of hullers, the rice is practically free from germ and outer bran.
Scouring is usually completed, by polishing in a brush machine. The polished rice contains
whole endosperms and broken particles of various sizes. Grading reels of disc separators
separates them.
The yield of white rice normally varies between 66% and 70%, based on the weight of rough
rice. As head rice is the most valuable product, its yield determines the milling quality of
rough rice. The price obtained for the various classes of broken rice decreases with size.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 34 of 162
A solvent-extraction process was developed to increase the yield of whole grain rice.
Dehulled brown rice is softened with rice oil, to improve bran removal. Fully milled rice is
sometimes treated with a talc-and-glucose solution to improve its appearance. After the
coating is evenly distributed on the kernels and dried with warm air, the rice emerges from
the equipment with a smooth, glistening luster and is known as coated rice.
The annual production of bran has a potential for 5 million tons of food protein and 6
million tons of edible oil; the husks, for 256,000 billion kcal as fuel; and the straw, for
30,000 billion kcal as metabolizable energy for cattle.
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A solvent-extraction process was developed to increase the yield of whole grain rice.
Dehulled brown rice is softened with rice oil, to improve bran removal. Fully milled rice is
sometimes treated with a talc-and-glucose solution to improve its appearance. After the
coating is evenly distributed on the kernels and dried with warm air, the rice emerges from
the equipment with a smooth, glistening luster and is known as coated rice.
The annual production of bran has a potential for 5 million tons of food protein and 6
million tons of edible oil; the husks, for 256,000 billion kcal as fuel; and the straw, for
30,000 billion kcal as metabolizable energy for cattle.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 35 of 162
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Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
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CHEMICAL COMPOSITION
Carbohydrates
Starch, the major component of rice, is present in the starchy endosperm as compound
granules that are 3-10 pm in size. Protein, the second major component, is present in the
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CHEMICAL COMPOSITION
Carbohydrates
Starch, the major component of rice, is present in the starchy endosperm as compound
granules that are 3-10 pm in size. Protein, the second major component, is present in the
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 37 of 162
endosperm in the form of discrete protein bodies that are 1-4 µm in size. The concentration
of nonstarchy carbohydrates is higher in the bran and germ fractions than in the starchy
endosperm. Brown rice contains about 8% protein, 75% carbohydrates, and small
amounts of fat, fiber, and ash. After milling, the protein content of rice is about 7% and the
carbohydrate content (mainly starch) about 78%. Starch is found primarily in the endosperm;
fat, fiber; minerals, and vitamins are concentrated in the aleurone layers and in the germ.
Starch, the main carbohydrate of rice, comprises up to 90% of the rice solids. In common
rice, amylose amounts to 12-35% of the total starch; in waxy (glutinous) rice, the amylose
content is much lower.
Proteins
Protein composition of milled rice is unique among cereals. The rice proteins are rich (at
least 80%) in glutelins and have a relatively good amino acid balance. Among the protein
fractions, albumin has the highest lysine content, followed by glutelin, globulin, and
prolamin. The high lysine content of rice protein is primarily due to their low prolamin content.
Proteins in milled rice are generally lower in lysine than proteins in brown rice.
The proportions of albumin and globulin and the total protein are highest in the outer layers
of the milled rice kernel and decrease toward the center; proportions of glutelin have an
inverse distribution. In rice, as in other cereal grains, the proteins differ considerably in their
amino acid composition and biological value. The most notable differences are in the high
concentration of lysine in albumins and of cystine in globulins, and in the very low lysine and
cystine concentrations in the prolamines. Rice protein is not ideally balanced; it is relatively
low in lysine concentration when compared with the FAO Reference Pattern;
supplementation with lysine and threonine significantly increases the biological value of rice
protein.
The subaleurone region, which is rich in protein, is only several cell layers thick, lies directly
beneath the aleurone, and is removed rather easily during milling. From a nutritional
standpoint, it is therefore desirable to mill rice as lightly as possible and retain some of the
protein in the subaleurone or to breed cultivars that have either an increased, number of
aleurone layers or have the protein more evenly distributed throughout the endosperm.
Protein content of the grain determines the protein distribution between bran polish and
milled rice. Protein distribution is more uniform throughout the grain as the grain increases in
total- protein content. Also, high-protein milled rices usually have more thiamine. The
increase in protein content is related mainly to an increase in the number of protein bodies
and a slight increase in their size.
Lipids
Brown rice contains 2.4-3.95% lipids. The lipid content depends on
·The variety
·Degree of maturity
·Growth conditions
·Lipid extraction method
The lipid content of bran and polished rice is affected by the degree of milling and the milling
procedure. Polishing gradually removes the pericarp, tegmen, aleurone layer, embryo, and
parts of the endosperm, but parts of the lipid-rich germ may remain attached to the
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endosperm in the form of discrete protein bodies that are 1-4 µm in size. The concentration
of nonstarchy carbohydrates is higher in the bran and germ fractions than in the starchy
endosperm. Brown rice contains about 8% protein, 75% carbohydrates, and small
amounts of fat, fiber, and ash. After milling, the protein content of rice is about 7% and the
carbohydrate content (mainly starch) about 78%. Starch is found primarily in the endosperm;
fat, fiber; minerals, and vitamins are concentrated in the aleurone layers and in the germ.
Starch, the main carbohydrate of rice, comprises up to 90% of the rice solids. In common
rice, amylose amounts to 12-35% of the total starch; in waxy (glutinous) rice, the amylose
content is much lower.
Proteins
Protein composition of milled rice is unique among cereals. The rice proteins are rich (at
least 80%) in glutelins and have a relatively good amino acid balance. Among the protein
fractions, albumin has the highest lysine content, followed by glutelin, globulin, and
prolamin. The high lysine content of rice protein is primarily due to their low prolamin content.
Proteins in milled rice are generally lower in lysine than proteins in brown rice.
The proportions of albumin and globulin and the total protein are highest in the outer layers
of the milled rice kernel and decrease toward the center; proportions of glutelin have an
inverse distribution. In rice, as in other cereal grains, the proteins differ considerably in their
amino acid composition and biological value. The most notable differences are in the high
concentration of lysine in albumins and of cystine in globulins, and in the very low lysine and
cystine concentrations in the prolamines. Rice protein is not ideally balanced; it is relatively
low in lysine concentration when compared with the FAO Reference Pattern;
supplementation with lysine and threonine significantly increases the biological value of rice
protein.
The subaleurone region, which is rich in protein, is only several cell layers thick, lies directly
beneath the aleurone, and is removed rather easily during milling. From a nutritional
standpoint, it is therefore desirable to mill rice as lightly as possible and retain some of the
protein in the subaleurone or to breed cultivars that have either an increased, number of
aleurone layers or have the protein more evenly distributed throughout the endosperm.
Protein content of the grain determines the protein distribution between bran polish and
milled rice. Protein distribution is more uniform throughout the grain as the grain increases in
total- protein content. Also, high-protein milled rices usually have more thiamine. The
increase in protein content is related mainly to an increase in the number of protein bodies
and a slight increase in their size.
Lipids
Brown rice contains 2.4-3.95% lipids. The lipid content depends on
·The variety
·Degree of maturity
·Growth conditions
·Lipid extraction method
The lipid content of bran and polished rice is affected by the degree of milling and the milling
procedure. Polishing gradually removes the pericarp, tegmen, aleurone layer, embryo, and
parts of the endosperm, but parts of the lipid-rich germ may remain attached to the
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 38 of 162
endosperm even after advanced polishing and removal of up to 20% of the rice kernel. The
major proportion of the lipid in rice is removed with the bran (containing the germ) and the
polish.
Oil in
·Bran 10.1-23.5%,
·Polish 9.1-11.5%,
·Brown rice 1.5-2.5%,
·Milled rice 0.3-0.7%
In the rice kernel, as in other cereals, lipid content is highest in the embryo and in the
aleurone layer, and the lipid is present as droplets or spherosomes. The spherosomes are
submicroscopic-about 0.5 µm or less in the coleoptile cells. Much higher quantities of lipids
are present outside the aleurone granules than inside them. The testa contains a fatty
material, and a sheath of fat-staining material encloses the aleurone granules. Rice lipids are
mainly triglycerides, with smaller amounts of phospholipids, glycolipids, and waxes. The
three main fatty acids are oleic, linoleic, and palmitic. The main glycolipids are acyl sterol
glycosides and sterol glycosides, and either diglycosyldiglyceride or ceramide,
monohexoside.
The distribution of lipid types is not uniform in the rice kernel. Approximate ratios of neutral
and polar lipids are 90:10 in bran, 50:50 in the starchy endosperm, and 33:67 in the
starch. Thus the bran is rich mainly in neutral lipids; the endosperm contains relatively
high concentrations of polar lipids.
Minerals
There is a considerably higher concentration of ash and of individual minerals in outer layers
of the milled rice kernel than toward the center. P, K, Mg, Fe, and Mn are concentrated in the
aleurone layer; P, K, and Mg are particularly high in the subcellular particles of the aleurone
layer; Ca is abundant in the pericarp. The phytin-P constitutes almost 90% of the total bran-
P and 40% of the milled rice-P.
Vitamins
Rice and its by-products contain little or no vitamin A, ascorbic acid, or vitamin D.
Thiamine, riboflavin, niacin, pyridoxine, pantothenic acid, folic acid, inositol, choline,
and biotin are lower in milled rice than in brown rice and substantially lower than in rice
bran, polish, or germ.
NUTRITIONAL IMPLICATIONS OF PROCESSING
Table 16-2 Composition of Rice (%)
Material MoistureProteinLipidFiberAsh Degree of Polishing
Brown Rice 15.5 7.4 2.3 1.0 1.3 0
Rice Bran 13.5 13.2 18.37.8 8.9 -----
Polished Rice15.5 6.2 0.8 0.3 0.6 8 - 10
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endosperm even after advanced polishing and removal of up to 20% of the rice kernel. The
major proportion of the lipid in rice is removed with the bran (containing the germ) and the
polish.
Oil in
·Bran 10.1-23.5%,
·Polish 9.1-11.5%,
·Brown rice 1.5-2.5%,
·Milled rice 0.3-0.7%
In the rice kernel, as in other cereals, lipid content is highest in the embryo and in the
aleurone layer, and the lipid is present as droplets or spherosomes. The spherosomes are
submicroscopic-about 0.5 µm or less in the coleoptile cells. Much higher quantities of lipids
are present outside the aleurone granules than inside them. The testa contains a fatty
material, and a sheath of fat-staining material encloses the aleurone granules. Rice lipids are
mainly triglycerides, with smaller amounts of phospholipids, glycolipids, and waxes. The
three main fatty acids are oleic, linoleic, and palmitic. The main glycolipids are acyl sterol
glycosides and sterol glycosides, and either diglycosyldiglyceride or ceramide,
monohexoside.
The distribution of lipid types is not uniform in the rice kernel. Approximate ratios of neutral
and polar lipids are 90:10 in bran, 50:50 in the starchy endosperm, and 33:67 in the
starch. Thus the bran is rich mainly in neutral lipids; the endosperm contains relatively
high concentrations of polar lipids.
Minerals
There is a considerably higher concentration of ash and of individual minerals in outer layers
of the milled rice kernel than toward the center. P, K, Mg, Fe, and Mn are concentrated in the
aleurone layer; P, K, and Mg are particularly high in the subcellular particles of the aleurone
layer; Ca is abundant in the pericarp. The phytin-P constitutes almost 90% of the total bran-
P and 40% of the milled rice-P.
Vitamins
Rice and its by-products contain little or no vitamin A, ascorbic acid, or vitamin D.
Thiamine, riboflavin, niacin, pyridoxine, pantothenic acid, folic acid, inositol, choline,
and biotin are lower in milled rice than in brown rice and substantially lower than in rice
bran, polish, or germ.
NUTRITIONAL IMPLICATIONS OF PROCESSING
Table 16-2 Composition of Rice (%)
Material MoistureProteinLipidFiberAsh Degree of Polishing
Brown Rice 15.5 7.4 2.3 1.0 1.3 0
Rice Bran 13.5 13.2 18.37.8 8.9 -----
Polished Rice15.5 6.2 0.8 0.3 0.6 8 - 10
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 39 of 162
Production of brown rice from rough rice increases protein, fat, and starch contents,
since the hulls are low in those constituents. Conversely, there is a decrease in the
crude Fiber and ash contents.
Conversion of brown rice to white or polished rice removes about 15% of the protein,
65% of the fat and fiber, and 55% of the minerals.
Rough rice and brown rice differ little in vitamin content, but conversion of brown rice to white
rice decreases the vitamin values considerably. Thus head rice contains only 20% as much
thiamine, 45% as much riboflavin, and 35% as much niacin as brown rice. The losses have
created much interest in the development of practical methods to retain more of the B
vitamins in the milled rice kernel. Processing the rice before milling to diffuse the vitamins
has approached the problem of improving the vitamin content of milled rice and other water-
soluble nutrients in the outer portion of the grain into the endosperm. Processing of rough
rice to increase vitamin retention involves parboiling or some modification thereof. For
parboiling, rough rice is soaked in water, drained, steamed, and dried. In 1940, a process for
the manufacture of "converted rice" was developed and patented in England. The cleaned
rough rice is exposed to a vacuum, treated with hot water under pressure, and then steamed,
dried, and milled. The converted rice process is particularly effective for the retention of
vitamins.
Parboiling is performed to improve the nutritional and also the storage and cooking attributes
of rice. The main modifications are transfer of some vitamins and minerals from the aleurone
and germ into the, starchy endosperm, dispersion of lipids from the aleurone layer and germ,
inactivation of enzymes, and destruction of molds and insects. Those changes are
accompanied by reduced chalkiness and increased vitreousness and translucence of the
milled rice, and improved digestibility and cooking properties.
Parboiling strengthens the attachment of the germ and aleurone to the starchy endosperm
and prevents the separation of the germ during husking. However, the strengthening of these
attachments and hardening of the endosperm increase the difficulty of milling the husked
grains of parboiled rice. Compared with nonparboiled rices, parboiled rices disintegrate less
during cooking and remain better separated and less sticky after cooking. Parboiling reduces
the amount of solids leached into the cooking water and the extent to which the kernels
solubilize during cooking.
Rice must have acceptable market and eating qualities and good nutritional value. Grain
quality is related mainly to the amylose/amylopectin ratio, which governs water absorption
and volume expansion during cooking, and to cohesiveness, color, gloss, and tenderness of
cooked rice. Long-grain types generally cook to dry, fluffy products that harden on keeping
and are preferred by some. Short-grain types tend to be more cohesive and moist and to
remain relatively tender when kept and consumed cold. Waxy (1-2% amylose) rices, in
contrast to high- amylose (over 25%) rices, are glossy and sticky when cooked. Rices with
intermediate amylose contents and intermediate gelatinization temperatures are preferred in
the tropics.
The modern trend in processed foods is toward convenience items. Precooking in water and
drying under controlled conditions or by application of dry heat may prepare quick-cooking
rices. Other convenience items include canned and frozen cooked rice.
PARBOILING
Traditional methods
e-- [email protected] Page 39 of 162
Production of brown rice from rough rice increases protein, fat, and starch contents,
since the hulls are low in those constituents. Conversely, there is a decrease in the
crude Fiber and ash contents.
Conversion of brown rice to white or polished rice removes about 15% of the protein,
65% of the fat and fiber, and 55% of the minerals.
Rough rice and brown rice differ little in vitamin content, but conversion of brown rice to white
rice decreases the vitamin values considerably. Thus head rice contains only 20% as much
thiamine, 45% as much riboflavin, and 35% as much niacin as brown rice. The losses have
created much interest in the development of practical methods to retain more of the B
vitamins in the milled rice kernel. Processing the rice before milling to diffuse the vitamins
has approached the problem of improving the vitamin content of milled rice and other water-
soluble nutrients in the outer portion of the grain into the endosperm. Processing of rough
rice to increase vitamin retention involves parboiling or some modification thereof. For
parboiling, rough rice is soaked in water, drained, steamed, and dried. In 1940, a process for
the manufacture of "converted rice" was developed and patented in England. The cleaned
rough rice is exposed to a vacuum, treated with hot water under pressure, and then steamed,
dried, and milled. The converted rice process is particularly effective for the retention of
vitamins.
Parboiling is performed to improve the nutritional and also the storage and cooking attributes
of rice. The main modifications are transfer of some vitamins and minerals from the aleurone
and germ into the, starchy endosperm, dispersion of lipids from the aleurone layer and germ,
inactivation of enzymes, and destruction of molds and insects. Those changes are
accompanied by reduced chalkiness and increased vitreousness and translucence of the
milled rice, and improved digestibility and cooking properties.
Parboiling strengthens the attachment of the germ and aleurone to the starchy endosperm
and prevents the separation of the germ during husking. However, the strengthening of these
attachments and hardening of the endosperm increase the difficulty of milling the husked
grains of parboiled rice. Compared with nonparboiled rices, parboiled rices disintegrate less
during cooking and remain better separated and less sticky after cooking. Parboiling reduces
the amount of solids leached into the cooking water and the extent to which the kernels
solubilize during cooking.
Rice must have acceptable market and eating qualities and good nutritional value. Grain
quality is related mainly to the amylose/amylopectin ratio, which governs water absorption
and volume expansion during cooking, and to cohesiveness, color, gloss, and tenderness of
cooked rice. Long-grain types generally cook to dry, fluffy products that harden on keeping
and are preferred by some. Short-grain types tend to be more cohesive and moist and to
remain relatively tender when kept and consumed cold. Waxy (1-2% amylose) rices, in
contrast to high- amylose (over 25%) rices, are glossy and sticky when cooked. Rices with
intermediate amylose contents and intermediate gelatinization temperatures are preferred in
the tropics.
The modern trend in processed foods is toward convenience items. Precooking in water and
drying under controlled conditions or by application of dry heat may prepare quick-cooking
rices. Other convenience items include canned and frozen cooked rice.
PARBOILING
Traditional methods
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 40 of 162
Parboiling of rice is a term that encompasses quite a variety of different processes, some of
them quite primitive technologically, others quite advanced. The basic or essential features
are that rough rice is first wetted, then heated, and finally dried. Many changes occur in
the rice kernel as a result of this treatment. Of particular importance are the translocation of
some nutrients from the outer layers to inner layers and the gelatinization of the
starch. Subsequently, the rice is milled and, of course, it must be cooked in water before
consumption.
It is said that parboiling was first developed in India as a method for facilitating removal of
the hulls from the rice kernel. In its earliest forms, parboiling consisted of soaking rough
rice (paddy) in warm water overnight and then drying the grain in the sun. The rice
hulls split open and were easily removed from the kernel. Later, it was learned that
parboiling provides nutritional benefits, since thiamin and other essential nutrients which are
normally present in fairly high concentrations in the bran (but at low concentrations in the
kernel) migrate to the endosperm during the water-soaking step. Since nearly all rice is
milled to remove the bran, parboiling preserves more of the nutritional values contained in
the whole grain. When hot water is used, the starch in the rice endosperm is changed
into a condition that causes the kernel to be more resistant to breakage and thus gives a
greater yield of whole kernels after milling.
e-- [email protected] Page 40 of 162
Parboiling of rice is a term that encompasses quite a variety of different processes, some of
them quite primitive technologically, others quite advanced. The basic or essential features
are that rough rice is first wetted, then heated, and finally dried. Many changes occur in
the rice kernel as a result of this treatment. Of particular importance are the translocation of
some nutrients from the outer layers to inner layers and the gelatinization of the
starch. Subsequently, the rice is milled and, of course, it must be cooked in water before
consumption.
It is said that parboiling was first developed in India as a method for facilitating removal of
the hulls from the rice kernel. In its earliest forms, parboiling consisted of soaking rough
rice (paddy) in warm water overnight and then drying the grain in the sun. The rice
hulls split open and were easily removed from the kernel. Later, it was learned that
parboiling provides nutritional benefits, since thiamin and other essential nutrients which are
normally present in fairly high concentrations in the bran (but at low concentrations in the
kernel) migrate to the endosperm during the water-soaking step. Since nearly all rice is
milled to remove the bran, parboiling preserves more of the nutritional values contained in
the whole grain. When hot water is used, the starch in the rice endosperm is changed
into a condition that causes the kernel to be more resistant to breakage and thus gives a
greater yield of whole kernels after milling.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 41 of 162
Soaking in water and then pressure-cooking to gelatinize the starch completely can parboil
rough rice. The rice is then dried and milled to remove the outer layers. Conditions used in
the soaking and cooking steps are critical with respect to the properties of the milled product,
particularly for its appearance and the yield of head rice.
The soaking step is carried out in warm water. In one variation, rice is elevated from storage
bins to an automatic scale hopper that weighs and dumps the rice into an accumulating
hopper. When rice sufficient to make a batch has been collected, it is dumped into a steeping
tank. This vessel is connected to a vacuum system, a, water system, and a compressed air
system. When the batch of rice is dropped into it, the tank is evacuated to remove air from
the grain. Then, sufficient water at a temperature of about 200ºF is introduced to cover the
rice. The tank is pressurized to about 100 psi and the rice is steeped about 190 min.
Temperature and time may be varied somewhat depending on the specific characteristics of
the rice used, its moisture content, time in storage, etc. During the steeping operation, water-
soluble B-vitamin components and minerals are infused into the endosperm from the bran,
PADDY
Soak in water at RT to 70º C to
saturation (about 30% moisture,
w.b.)
Moisten or Partially
Soak (18-20% Moisture)
Drain
Cook by conduction heating
(with hot air and sand )
EXPANDED RICE
Cook by
steaming
Shel
l
Mill
Conduction heat
(With hot air and
sand)
PRESSURE
PARBOILED
RICE
FLAKED
RICE
Dry
Flake with
roller flaker
CONVENTIONA
L PARBOILED
RICE
Flake with
edge runner
Partially whiten
Cook by
steaming under
pressure
Mill
Dry
DRY HEAT
PARBOILED
RICE
Mill
Dry
Flow chart of steps for making dfferent kinds of parboiled rice and expanded and flaked
rice. RT= Room Temperature
e-- [email protected] Page 41 of 162
Soaking in water and then pressure-cooking to gelatinize the starch completely can parboil
rough rice. The rice is then dried and milled to remove the outer layers. Conditions used in
the soaking and cooking steps are critical with respect to the properties of the milled product,
particularly for its appearance and the yield of head rice.
The soaking step is carried out in warm water. In one variation, rice is elevated from storage
bins to an automatic scale hopper that weighs and dumps the rice into an accumulating
hopper. When rice sufficient to make a batch has been collected, it is dumped into a steeping
tank. This vessel is connected to a vacuum system, a, water system, and a compressed air
system. When the batch of rice is dropped into it, the tank is evacuated to remove air from
the grain. Then, sufficient water at a temperature of about 200ºF is introduced to cover the
rice. The tank is pressurized to about 100 psi and the rice is steeped about 190 min.
Temperature and time may be varied somewhat depending on the specific characteristics of
the rice used, its moisture content, time in storage, etc. During the steeping operation, water-
soluble B-vitamin components and minerals are infused into the endosperm from the bran,
PADDY
Soak in water at RT to 70º C to
saturation (about 30% moisture,
w.b.)
Moisten or Partially
Soak (18-20% Moisture)
Drain
Cook by conduction heating
(with hot air and sand )
EXPANDED RICE
Cook by
steaming
Shel
l
Mill
Conduction heat
(With hot air and
sand)
PRESSURE
PARBOILED
RICE
FLAKED
RICE
Dry
Flake with
roller flaker
CONVENTIONA
L PARBOILED
RICE
Flake with
edge runner
Partially whiten
Cook by
steaming under
pressure
Mill
Dry
DRY HEAT
PARBOILED
RICE
Mill
Dry
Flow chart of steps for making dfferent kinds of parboiled rice and expanded and flaked
rice. RT= Room Temperature
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 42 of 162
germ, and hull. At the end of this step, water is drained off and the rice is discharged into a
jacketed rotating vacuum drier equipped with steam tubes.
Variations in properties of different lots of rough rice may affect their response to soaking
conditions, although acceptable products may be obtained over a wide range of conditions.
Poor results are obtained at soaking temperatures above the gelatinization temperature of
the starch. Incomplete soaking or tempering is reflected in excessive breakage of kernels
when the rice is cooked, dried, and milled. For example, Calrose rice soaked at 150ºF for
two hours followed by one hour of tempering before it was cooked and dried yielded more
than 30% broken kernels in the standard milling test.
In the drier, the soaked rice is vacuumized and heated with steam to remove excess
moisture. Dry steam is then injected to gelatinize the starch in the grains, after which the
vessel is vented and evacuated until the moisture of the rice becomes low enough to permit it
to be milled successfully. The dried rice is conveyed to bins where it is cooled by drawing air
through it, and tempered to equalize the moisture content of the batch. Finally, the rice is
milled to remove the bull, bran, and germ. Examples of conditions that have proved to be
successful for cooking are steam pressures of 20 psi for 5 to 8 minutes. Then, drying could
be conducted at 120ºF in a cross flow air drier.
In another process, cleaned rice is steeped in two parts of water at 130º to 150ºF in open
steel tanks for 9 to 12 hr until the rice has absorbed 30 to 35% moisture on the wet basis.
The soaked rice is transferred continuously to a vertical pressure vessel equipped with rotary
valves on the inlet and discharge openings. There it is steamed at 230º to 245º F for 8 to 20
minutes, depending on the degree of parboiling and the cooking quality and color desired in
the end product. Shorter cooking times result in rice of lighter color. Little additional water is
absorbed in the steaming process, and the rice is discharged with moisture content of about
35%. It is dried in a steam tube drier and a series of hot air driers to 11 to 13% moisture, and
then milled in conventional equipment. Yields are from 66 to 71 lb of total milled rice and 58
to 67 lb of whole grains per 100 lb of the original rough rice. The product is said to contain
2.0 mg of thiamin, 0.40 mg of riboflavin, and 44.0 mg of niacin per kg of dry material. Its
useful storage life is about 2 to 3 years. Milling by-products are disposed of in regular
commercial channels for these materials. The wastewater from the steeping process is
generally not utilized; although it could be dried to yield a material having some nutritional
value, for feed, this would not be an economically viable operation.
A third process is similar to the second in general principles, except that both the soaking
and steaming steps are performed in rotating cylinders.
Another variant of the parboiling process consists of the following steps. Rice is tempered in
hot or cold water, depending on the variety, and is then conveyed to soaking tanks each of
which hold 15,000 lb of rice. Hot (100º to 200ºF) water is added and the rice is allowed to
soak for 1 to 10 hr, depending on the variety. After soaking, the rice is transferred through a
rotary valve to a screw conveyor passing through a pressure vessel. Here the grain is
cooked at 15 to 100 psi steam pressure for 10 see to 3 min. Cooked kernels exit through
another valve, and are cooled and dried before milling.
Modern commercial parboiling processes generally include the steps of
1 Soaking the rough rice in 50º to 70º C water for 3 to 4 hours to yield rough rice
having 30% moisture content;
2 Draining the free water from the soaked rough rice;
e-- [email protected] Page 42 of 162
germ, and hull. At the end of this step, water is drained off and the rice is discharged into a
jacketed rotating vacuum drier equipped with steam tubes.
Variations in properties of different lots of rough rice may affect their response to soaking
conditions, although acceptable products may be obtained over a wide range of conditions.
Poor results are obtained at soaking temperatures above the gelatinization temperature of
the starch. Incomplete soaking or tempering is reflected in excessive breakage of kernels
when the rice is cooked, dried, and milled. For example, Calrose rice soaked at 150ºF for
two hours followed by one hour of tempering before it was cooked and dried yielded more
than 30% broken kernels in the standard milling test.
In the drier, the soaked rice is vacuumized and heated with steam to remove excess
moisture. Dry steam is then injected to gelatinize the starch in the grains, after which the
vessel is vented and evacuated until the moisture of the rice becomes low enough to permit it
to be milled successfully. The dried rice is conveyed to bins where it is cooled by drawing air
through it, and tempered to equalize the moisture content of the batch. Finally, the rice is
milled to remove the bull, bran, and germ. Examples of conditions that have proved to be
successful for cooking are steam pressures of 20 psi for 5 to 8 minutes. Then, drying could
be conducted at 120ºF in a cross flow air drier.
In another process, cleaned rice is steeped in two parts of water at 130º to 150ºF in open
steel tanks for 9 to 12 hr until the rice has absorbed 30 to 35% moisture on the wet basis.
The soaked rice is transferred continuously to a vertical pressure vessel equipped with rotary
valves on the inlet and discharge openings. There it is steamed at 230º to 245º F for 8 to 20
minutes, depending on the degree of parboiling and the cooking quality and color desired in
the end product. Shorter cooking times result in rice of lighter color. Little additional water is
absorbed in the steaming process, and the rice is discharged with moisture content of about
35%. It is dried in a steam tube drier and a series of hot air driers to 11 to 13% moisture, and
then milled in conventional equipment. Yields are from 66 to 71 lb of total milled rice and 58
to 67 lb of whole grains per 100 lb of the original rough rice. The product is said to contain
2.0 mg of thiamin, 0.40 mg of riboflavin, and 44.0 mg of niacin per kg of dry material. Its
useful storage life is about 2 to 3 years. Milling by-products are disposed of in regular
commercial channels for these materials. The wastewater from the steeping process is
generally not utilized; although it could be dried to yield a material having some nutritional
value, for feed, this would not be an economically viable operation.
A third process is similar to the second in general principles, except that both the soaking
and steaming steps are performed in rotating cylinders.
Another variant of the parboiling process consists of the following steps. Rice is tempered in
hot or cold water, depending on the variety, and is then conveyed to soaking tanks each of
which hold 15,000 lb of rice. Hot (100º to 200ºF) water is added and the rice is allowed to
soak for 1 to 10 hr, depending on the variety. After soaking, the rice is transferred through a
rotary valve to a screw conveyor passing through a pressure vessel. Here the grain is
cooked at 15 to 100 psi steam pressure for 10 see to 3 min. Cooked kernels exit through
another valve, and are cooled and dried before milling.
Modern commercial parboiling processes generally include the steps of
1 Soaking the rough rice in 50º to 70º C water for 3 to 4 hours to yield rough rice
having 30% moisture content;
2 Draining the free water from the soaked rough rice;
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 43 of 162
3 Applying steam heat under pressure for 15 to 20 minutes to gelatinize the
starch and to raise the water content to about 35%; and
4 Drying the steamed rice with hot air to reduce its moisture content to about
14%. The dried rice is then milled.
Properties:
Milling yield is higher after parboiling and there are fewer broken grains, i.e., there is a
greater percentage of head rice. The grain structure becomes compact, translucent, and
shiny. Germination is no longer possible, so some storage problems are alleviated. The
endosperm is denser, making it more resistant to insect attack, and the grains remain firmer
during cooking and are less sticky.
According to Luh and Mickus (1980), the most important changes occurring in parboiling
processes are:
(1) The water-soluble vitamins and mineral salts are spread throughout the grain, thus
altering their distribution and concentration among its various parts. The riboflavin and
thiamin contents are four times higher and the niacin level is eight times greater in parboiled
rice than in whole rice. Thiamin is more evenly distributed in the parboiled rice.
(2) Moisture content is reduced to 10 to 11%.
(3) The starch grains imbedded in a proteinaceous matrix are gelatinized and
expanded until they fill up the surrounding air spaces.
(4) The protein substances are separated and sink into the compact mass of
gelatinized starch, becoming less susceptible to extraction.
(5) Enzymes present in the kernel are partially or entirely inactivated.
(6) Microorganisms and insect forms are either killed or greatly reduced in number.
Parboiled rice has a somewhat elastic texture, and for that reason resists breakage when it is
milled. The better head rice yields obtained from the milling of parboiled rice, as compared to
raw rice, defrays to a considerable extent the cost of parboiling so that the parboiled product
generally does not sell for much more than white rice.
Although parboiled rice is not quick cooking, it has certain advantages over raw rice. It is
more resistant to insect infestations and it does not break up as much when used in canned
formulations such as soups and puddings. When overcooked, it does not become as mushy
as raw rice. Parboiled rice is darker than raw milled rice and has a slightly different flavor, but
it is widely accepted and is often preferred to white rice. in some rice-eating areas of the
world, however, attempts to introduce it have not been successful. Its color, which is usually
a light tan, is probably an adverse factor for consumers who look upon extreme whiteness as
a indication of high quality.
Advantages of parboiling
Parboiling of paddy has following advantages:
1.Dehusking of parboiled rice becomes easy.
2.The germ becomes tougher resulting in reduced losses during milling.
3.Milling parboiled rice has greater resistance to insect and fungus infection.
4.The nutritive value of the rice increases after parboiling because the water dissolves
the vitamins and minerals present in the hull & bran coat and carries them into the
endosperm resulting in no loss of valuable nutrients.
5.The milling and polishing of raw rice result in losses of 75% of Vitamin B1, 56% of
Riboflavin and 63% of Niacin whereas after parboiling these losses are reduced by
58%, 35% and 11% respectively.
e-- [email protected] Page 43 of 162
3 Applying steam heat under pressure for 15 to 20 minutes to gelatinize the
starch and to raise the water content to about 35%; and
4 Drying the steamed rice with hot air to reduce its moisture content to about
14%. The dried rice is then milled.
Properties:
Milling yield is higher after parboiling and there are fewer broken grains, i.e., there is a
greater percentage of head rice. The grain structure becomes compact, translucent, and
shiny. Germination is no longer possible, so some storage problems are alleviated. The
endosperm is denser, making it more resistant to insect attack, and the grains remain firmer
during cooking and are less sticky.
According to Luh and Mickus (1980), the most important changes occurring in parboiling
processes are:
(1) The water-soluble vitamins and mineral salts are spread throughout the grain, thus
altering their distribution and concentration among its various parts. The riboflavin and
thiamin contents are four times higher and the niacin level is eight times greater in parboiled
rice than in whole rice. Thiamin is more evenly distributed in the parboiled rice.
(2) Moisture content is reduced to 10 to 11%.
(3) The starch grains imbedded in a proteinaceous matrix are gelatinized and
expanded until they fill up the surrounding air spaces.
(4) The protein substances are separated and sink into the compact mass of
gelatinized starch, becoming less susceptible to extraction.
(5) Enzymes present in the kernel are partially or entirely inactivated.
(6) Microorganisms and insect forms are either killed or greatly reduced in number.
Parboiled rice has a somewhat elastic texture, and for that reason resists breakage when it is
milled. The better head rice yields obtained from the milling of parboiled rice, as compared to
raw rice, defrays to a considerable extent the cost of parboiling so that the parboiled product
generally does not sell for much more than white rice.
Although parboiled rice is not quick cooking, it has certain advantages over raw rice. It is
more resistant to insect infestations and it does not break up as much when used in canned
formulations such as soups and puddings. When overcooked, it does not become as mushy
as raw rice. Parboiled rice is darker than raw milled rice and has a slightly different flavor, but
it is widely accepted and is often preferred to white rice. in some rice-eating areas of the
world, however, attempts to introduce it have not been successful. Its color, which is usually
a light tan, is probably an adverse factor for consumers who look upon extreme whiteness as
a indication of high quality.
Advantages of parboiling
Parboiling of paddy has following advantages:
1.Dehusking of parboiled rice becomes easy.
2.The germ becomes tougher resulting in reduced losses during milling.
3.Milling parboiled rice has greater resistance to insect and fungus infection.
4.The nutritive value of the rice increases after parboiling because the water dissolves
the vitamins and minerals present in the hull & bran coat and carries them into the
endosperm resulting in no loss of valuable nutrients.
5.The milling and polishing of raw rice result in losses of 75% of Vitamin B1, 56% of
Riboflavin and 63% of Niacin whereas after parboiling these losses are reduced by
58%, 35% and 11% respectively.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 44 of 162
6.The parboiled rice will not turn into a gluten mass when cooked.
Disadvantages of parboiling
1.Parboiling changes the colour of the grain.
2.Sometimes unpleasant smell of parboiled rice is not preferred.
These changes are due to defective steeping while parboiling. During steeping
fermentative changes result in yellowish colour and off flavours of rice.
Section 1 : Definitions of rice
The meaning of the terminology in this Rice Standards is as follows:
1. Rice Standards means the minimum specifications of rice of each type and grade for
domestic and international trade.
2. Rice means non-glutinous and glutinous rice (Oryzae sativa L.) in whatever form.
3. Paddy means rice that is not yet dehusked.
4. Cargo rice (Loonzain rice, Brown rice, Husked rice) means rice that is dehusked only.
5. White rice means rice that is obtained by removing bran from Cargo non-glutinous rice.
6. White glutinous rice means rice that is obtained by removing bran from Cargo glutinous
rice.
7. Parboiled rice means non-glutinous rice that has passed through the parboiling process
and has its bran removed.
8. Rice classification means rice kernels of various lengths as specified, which are the
mixture of rice kernels of each class in accordance with the specified proportion.
9. Classes of rice kernels mean classes of rice kernels that are classified in accordance
with the length of the whole kernel.
10. Parts of rice kernels mean each part of the whole kernel that is divided lengthwise into
10 equal parts.
11. Whole kernels mean rice kernels that are in whole condition without any broken part,
including the kernels that have length as from 9 parts onward.
12. Head rice means broken kernels whose lengths are more than those of Brokens but
have not reached the length of the whole kernel. This includes split kernels that retain the
area as from 80% of the whole kernel.
13. Brokens mean broken kernels that have the length as from 2.5 parts but have not
reached the length of Head rice. This includes split kernels that retain the area less than 80%
of the whole kernel.
14. Small brokens C1 mean small broken kernels that pass through round hole metal sieve
No.7.
e-- [email protected] Page 44 of 162
6.The parboiled rice will not turn into a gluten mass when cooked.
Disadvantages of parboiling
1.Parboiling changes the colour of the grain.
2.Sometimes unpleasant smell of parboiled rice is not preferred.
These changes are due to defective steeping while parboiling. During steeping
fermentative changes result in yellowish colour and off flavours of rice.
Section 1 : Definitions of rice
The meaning of the terminology in this Rice Standards is as follows:
1. Rice Standards means the minimum specifications of rice of each type and grade for
domestic and international trade.
2. Rice means non-glutinous and glutinous rice (Oryzae sativa L.) in whatever form.
3. Paddy means rice that is not yet dehusked.
4. Cargo rice (Loonzain rice, Brown rice, Husked rice) means rice that is dehusked only.
5. White rice means rice that is obtained by removing bran from Cargo non-glutinous rice.
6. White glutinous rice means rice that is obtained by removing bran from Cargo glutinous
rice.
7. Parboiled rice means non-glutinous rice that has passed through the parboiling process
and has its bran removed.
8. Rice classification means rice kernels of various lengths as specified, which are the
mixture of rice kernels of each class in accordance with the specified proportion.
9. Classes of rice kernels mean classes of rice kernels that are classified in accordance
with the length of the whole kernel.
10. Parts of rice kernels mean each part of the whole kernel that is divided lengthwise into
10 equal parts.
11. Whole kernels mean rice kernels that are in whole condition without any broken part,
including the kernels that have length as from 9 parts onward.
12. Head rice means broken kernels whose lengths are more than those of Brokens but
have not reached the length of the whole kernel. This includes split kernels that retain the
area as from 80% of the whole kernel.
13. Brokens mean broken kernels that have the length as from 2.5 parts but have not
reached the length of Head rice. This includes split kernels that retain the area less than 80%
of the whole kernel.
14. Small brokens C1 mean small broken kernels that pass through round hole metal sieve
No.7.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 45 of 162
15. Undermilled kernels mean milled rice kernels that have the milling degree below that
specified for each grade of rice.
16. Red kernels mean rice kernels that have red bran covering the kernels wholly or partly.
17. Yellow kernels mean rice kernels that have some parts of the kernels turn yellow
obviously. This includes parboiled rice kernels that are light brown partly or wholly.
18. Black kernels mean parboiled rice kernels that are black for the whole kernels, including
kernels that are dark brown for the whole kernels.
19. Partly black kernels mean parboiled rice kernels that have black or dark brown area on
the kernels as from 2.5 parts onward but not reaching the whole kernels.
20. Peck kernels mean parboiled rice kernels that have obviously black or dark brown area
on the kernels not reaching 2.5 parts.
21. Chalky kernels mean non-glutinous rice kernels that have an opaque area like chalk
covering the kernels from 50% onward.
22. Damaged kernels mean kernels that are obviously damaged as can be seen by the
naked eyes due to moisture, heat, fungi, insects or other.
23. Undeveloped kernels mean kernels that do not develop normally as should be, and are
flat without starch.
24. Immature kernels mean rice kernels that are light green, obtained from immature paddy.
25. Other seeds mean seeds of other plants than rice kernels.
26. Foreign matter means other matter than rice. This includes rice husk and bran detached
from rice kernels.
27. Milling degree means the degree to which the rice is milled.
28. Sieve means round hole metal sieve No.7, that is 0.79mm. (0.031 inch) thick and with
hole diameter of 1.75mm 0.069 inch).
29. The unit "per cent" means percentage by weight except for per cent of grain
classification which is percentage by quantity.
Rice Types:
Thai Jasmine White Rice, also called fragrant rice or "Hom Mali" rice, is
recognized world wide as Thailand's specialty.
Thai Jasmine Rice belongs to the Indica (long-grain) category and could be
divided into 3 main categories as A, B and C according to their quality; Prime
Quality, Superb Quality and Premium Quality.
e-- [email protected] Page 45 of 162
15. Undermilled kernels mean milled rice kernels that have the milling degree below that
specified for each grade of rice.
16. Red kernels mean rice kernels that have red bran covering the kernels wholly or partly.
17. Yellow kernels mean rice kernels that have some parts of the kernels turn yellow
obviously. This includes parboiled rice kernels that are light brown partly or wholly.
18. Black kernels mean parboiled rice kernels that are black for the whole kernels, including
kernels that are dark brown for the whole kernels.
19. Partly black kernels mean parboiled rice kernels that have black or dark brown area on
the kernels as from 2.5 parts onward but not reaching the whole kernels.
20. Peck kernels mean parboiled rice kernels that have obviously black or dark brown area
on the kernels not reaching 2.5 parts.
21. Chalky kernels mean non-glutinous rice kernels that have an opaque area like chalk
covering the kernels from 50% onward.
22. Damaged kernels mean kernels that are obviously damaged as can be seen by the
naked eyes due to moisture, heat, fungi, insects or other.
23. Undeveloped kernels mean kernels that do not develop normally as should be, and are
flat without starch.
24. Immature kernels mean rice kernels that are light green, obtained from immature paddy.
25. Other seeds mean seeds of other plants than rice kernels.
26. Foreign matter means other matter than rice. This includes rice husk and bran detached
from rice kernels.
27. Milling degree means the degree to which the rice is milled.
28. Sieve means round hole metal sieve No.7, that is 0.79mm. (0.031 inch) thick and with
hole diameter of 1.75mm 0.069 inch).
29. The unit "per cent" means percentage by weight except for per cent of grain
classification which is percentage by quantity.
Rice Types:
Thai Jasmine White Rice, also called fragrant rice or "Hom Mali" rice, is
recognized world wide as Thailand's specialty.
Thai Jasmine Rice belongs to the Indica (long-grain) category and could be
divided into 3 main categories as A, B and C according to their quality; Prime
Quality, Superb Quality and Premium Quality.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 46 of 162
Brown Rice belongs to the Indica (long-grain), similar to white rice.
The only difference between these two varieties is the milling. As a result, in
brown rice, only the husk is removed while the bran layer remains.
Because of the bran layer, brown rice contains more nutrients than white
rice. In particular, Brown rice is very high in fiber and vitamin B.
White Rice belongs to the Indica (long-grain) category. It is also known as
polished rice or fully milled rice because most of the outer layer-the husk and
the bran layer-are removed from the kernel, through the milling process.
Broken Rice, during the milling process, broken rice is separated from the
white rice, which shape remains intact. In other words, broken rice is the
damaged white rice.
A grain of broken rice gives a low fiber texture and low nutrient level, while
retaining its high energy content.
Short Grain Rice belongs to the Japonica (short-grain) category and has
short, round, and plumpy kernel. When cooked, short-grained rice is stick
together, although not as much as glutinous rice.
In Japanese and Korean cuisine, short-grained rice is primary consumed in
every meal.
Parboiled Rice means non-glutinous rice that has passed through the
parboiling process and has its bran removed.
Parboiled rice are divided into 9 grades: 1) 100% Sorted 2) 100%
3) 5% Sorted 4) 5% 5) 10% Sorted 6) 10% 6) 10% 7) 15%
8) 25% 9) Broken rice A1
Glutinous Rice also called sticky rice or sweet rice, consists of amylose and
amylopectin starch. With a chalky white texture.
The standards for White glutinous rice are specified as follows:
White glutinous rice 10%
- Short Grain
- Long Grain
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Brown Rice belongs to the Indica (long-grain), similar to white rice.
The only difference between these two varieties is the milling. As a result, in
brown rice, only the husk is removed while the bran layer remains.
Because of the bran layer, brown rice contains more nutrients than white
rice. In particular, Brown rice is very high in fiber and vitamin B.
White Rice belongs to the Indica (long-grain) category. It is also known as
polished rice or fully milled rice because most of the outer layer-the husk and
the bran layer-are removed from the kernel, through the milling process.
Broken Rice, during the milling process, broken rice is separated from the
white rice, which shape remains intact. In other words, broken rice is the
damaged white rice.
A grain of broken rice gives a low fiber texture and low nutrient level, while
retaining its high energy content.
Short Grain Rice belongs to the Japonica (short-grain) category and has
short, round, and plumpy kernel. When cooked, short-grained rice is stick
together, although not as much as glutinous rice.
In Japanese and Korean cuisine, short-grained rice is primary consumed in
every meal.
Parboiled Rice means non-glutinous rice that has passed through the
parboiling process and has its bran removed.
Parboiled rice are divided into 9 grades: 1) 100% Sorted 2) 100%
3) 5% Sorted 4) 5% 5) 10% Sorted 6) 10% 6) 10% 7) 15%
8) 25% 9) Broken rice A1
Glutinous Rice also called sticky rice or sweet rice, consists of amylose and
amylopectin starch. With a chalky white texture.
The standards for White glutinous rice are specified as follows:
White glutinous rice 10%
- Short Grain
- Long Grain
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 47 of 162
BROWN RICE versus WHITE RICE
Brown Rice Tips the Scale for Good Nutrition
Milling is the primary difference between brown and white rice. The varieties may be
identical, but it is in the milling process where brown rice becomes white rice. Milling, often
called "whitening", removes the outer bran layer of the rice grain.
What does that do to the rice grain? Does milling affect the nutritional quality of the rice? The
answer to this question is YES. Milling strips off the bran layer, leaving a core comprised of
mostly carbohydrates. In this bran layer resides nutrients of vital importance in the diet,
making white rice a poor competitor in the nutrition game. The following chart shows the
nutritional differences between brown and white rices. Fiber is dramatically lower in white
rice, as are the oils, most of the B vitamins, and important minerals.
Brown Rice White Rice
1 cup 1 cup
Calories 232 223
Protein 4.88 g 4.10 g
Carbohydrate 49.7 g 49.6 g
Fat 1.17 g 0.205 g
Dietary Fiber 3.32 g 0.74 g
Thiamin (B1) 0.176 mg 0.223 mg
Riboflavin (B2) 0.039 mg 0.021 mg
Niacin (B3) 2.730 mg 2.050 mg
Vitamin B6 0.294 mg 0.103 mg
Folacin 10 mcg 4.1 mcg
Vitamin E 1.4 mg 0.462 mg
Magnesium 72.2 mg 22.6 mg
Phosphorus 142 mg 57.4 mg
Potassium 137 mg 57.4 mg
Selenium 26 mg 19 mg
Zinc 1.05 mg 0.841 mg
Bran contains several things of major importance - two major ones are fiber and essential
oils. Fiber is not only filling, but is implicated in prevention of major diseases in this country
such as certain gastrointestinal diseases and heart disease. The National Cancer Institute
recommends 25 grams of fiber a day, a cup of brown rice adds nearly 3.5 g, while an equal
amount of white rice not even 1 g. Also, components of the oils present in rice bran have
been shown in numerous studies to decrease serum cholesterol, a major risk factor in heart
disease.
According to the USDA's new food guide pyramid with six major food groups (fats, dairy,
protein, vegetables, fruits, and starches), starches should comprise the major portion of the
diet - about 58% - which translates into 6-11 servings of carbohydrate a day. Whole grains
such as brown rice figure prominently in this group. A one cup serving of brown rice yields
about 50 grams of carbohydrate. In addition, it has been shown that diet rich in
carbohydrates can be useful in weight control. Studies show that diets with identical caloric
loads but one richer in fats and protein versus a diet rich in carbohydrate tends to contribute
to weight gain. Dietary fat tends to go to body fat stores whereas dietary carbohydrate tends
to be utilized or held in muscle stores for a period of time. We are much better off, then, to
eat a well balanced diet low in fat and rich in complex carbohydrates. Brown rice rounds out
the diet in a way white rice cannot begin to approach.
e-- [email protected] Page 47 of 162
BROWN RICE versus WHITE RICE
Brown Rice Tips the Scale for Good Nutrition
Milling is the primary difference between brown and white rice. The varieties may be
identical, but it is in the milling process where brown rice becomes white rice. Milling, often
called "whitening", removes the outer bran layer of the rice grain.
What does that do to the rice grain? Does milling affect the nutritional quality of the rice? The
answer to this question is YES. Milling strips off the bran layer, leaving a core comprised of
mostly carbohydrates. In this bran layer resides nutrients of vital importance in the diet,
making white rice a poor competitor in the nutrition game. The following chart shows the
nutritional differences between brown and white rices. Fiber is dramatically lower in white
rice, as are the oils, most of the B vitamins, and important minerals.
Brown Rice White Rice
1 cup 1 cup
Calories 232 223
Protein 4.88 g 4.10 g
Carbohydrate 49.7 g 49.6 g
Fat 1.17 g 0.205 g
Dietary Fiber 3.32 g 0.74 g
Thiamin (B1) 0.176 mg 0.223 mg
Riboflavin (B2) 0.039 mg 0.021 mg
Niacin (B3) 2.730 mg 2.050 mg
Vitamin B6 0.294 mg 0.103 mg
Folacin 10 mcg 4.1 mcg
Vitamin E 1.4 mg 0.462 mg
Magnesium 72.2 mg 22.6 mg
Phosphorus 142 mg 57.4 mg
Potassium 137 mg 57.4 mg
Selenium 26 mg 19 mg
Zinc 1.05 mg 0.841 mg
Bran contains several things of major importance - two major ones are fiber and essential
oils. Fiber is not only filling, but is implicated in prevention of major diseases in this country
such as certain gastrointestinal diseases and heart disease. The National Cancer Institute
recommends 25 grams of fiber a day, a cup of brown rice adds nearly 3.5 g, while an equal
amount of white rice not even 1 g. Also, components of the oils present in rice bran have
been shown in numerous studies to decrease serum cholesterol, a major risk factor in heart
disease.
According to the USDA's new food guide pyramid with six major food groups (fats, dairy,
protein, vegetables, fruits, and starches), starches should comprise the major portion of the
diet - about 58% - which translates into 6-11 servings of carbohydrate a day. Whole grains
such as brown rice figure prominently in this group. A one cup serving of brown rice yields
about 50 grams of carbohydrate. In addition, it has been shown that diet rich in
carbohydrates can be useful in weight control. Studies show that diets with identical caloric
loads but one richer in fats and protein versus a diet rich in carbohydrate tends to contribute
to weight gain. Dietary fat tends to go to body fat stores whereas dietary carbohydrate tends
to be utilized or held in muscle stores for a period of time. We are much better off, then, to
eat a well balanced diet low in fat and rich in complex carbohydrates. Brown rice rounds out
the diet in a way white rice cannot begin to approach.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 48 of 162
CORN (MAIZE)
omponent parts of mature dent corn kernels and their chemical composition are given in Table
17- 1. About three-fifths of the processed corn (or maize; the terms are used interchangeably)
is used to produce corn starch, sweeteners, corn oil, and various feed by-products. The
remainder is used to prepare various food products and alcoholic beverages.
C
Corn is prepared in several ways as human food:
·Parched to be eaten whole
·Ground to make hominy, corn meal, or corn flour
·Treated with alkali to remove the pericarp and germ to make lye hominy
·Converted to a variety of breakfast foods
DRY MILLING
Dry milling of corn is carried out by the old-process milling from nondegermed grain and by
the new-process milling from degermed grain.
Old-Process Milling
In the old process, corn is ground to a coarse meal between millstones run slowly at a low
temperature, with the meal frequently not being sifted. In the larger mills, about 5% of the coarser
particles of the hull are sifted out. The meal is essentially a whole corn product and has a rich, oily
flavor, as it contains much of the germ. The product stores poorly. The meal is soft and flour-like. In
some larger mills, the corn is dried to 10-12% moisture before grinding. Kiln drying facilitates rapid
grinding and improves the keeping qualities of the meal.
Table 17-2 Yield and Particle- Size Range of Milled Corn Products
Product Particle Size Yield (%)
Mesh Inches
Grits 14-28 0.054-0.028 40
Coarse meal 28-50 0.028-0.0145 20
Fine meal 50-75 0.0145-0.0095 10
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CORN (MAIZE)
omponent parts of mature dent corn kernels and their chemical composition are given in Table
17- 1. About three-fifths of the processed corn (or maize; the terms are used interchangeably)
is used to produce corn starch, sweeteners, corn oil, and various feed by-products. The
remainder is used to prepare various food products and alcoholic beverages.
C
Corn is prepared in several ways as human food:
·Parched to be eaten whole
·Ground to make hominy, corn meal, or corn flour
·Treated with alkali to remove the pericarp and germ to make lye hominy
·Converted to a variety of breakfast foods
DRY MILLING
Dry milling of corn is carried out by the old-process milling from nondegermed grain and by
the new-process milling from degermed grain.
Old-Process Milling
In the old process, corn is ground to a coarse meal between millstones run slowly at a low
temperature, with the meal frequently not being sifted. In the larger mills, about 5% of the coarser
particles of the hull are sifted out. The meal is essentially a whole corn product and has a rich, oily
flavor, as it contains much of the germ. The product stores poorly. The meal is soft and flour-like. In
some larger mills, the corn is dried to 10-12% moisture before grinding. Kiln drying facilitates rapid
grinding and improves the keeping qualities of the meal.
Table 17-2 Yield and Particle- Size Range of Milled Corn Products
Product Particle Size Yield (%)
Mesh Inches
Grits 14-28 0.054-0.028 40
Coarse meal 28-50 0.028-0.0145 20
Fine meal 50-75 0.0145-0.0095 10
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
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Flour Through 75 Below 0.0095 5
Germ 3-30 0.292-0.0268 14
Hominy feed 11
New-Process Milling
In this process, steel rolls are used as in the milling of wheat. The objective is to remove the bran and
germ and to recover the endosperm in the farm of hominy or corn grits, coarse meal, fine meal, and
corn flour. Corn grits and coarse, meal consist largely of particles of flinty endosperm, and the fine
meal and corn flour are obtained mainly from the soft and starchy endosperm. Flint varieties of corn
are considered too "sharp" for grinding to a meal. Dent corn is almost invariably used. Since the grits
used in the manufacture of corn flakes are made mainly from white corn, large quantities are used to
make grits. Meal and flour are considered as by-products.
The corn is cleaned and passed through a scourer to remove the tip cap from the germ end of the
kernel. The hilar layer under the tip is frequently black, and it causes black specks in the meal. The
corn is tempered by two additions of water to moisture content of 21-24%. Subsequently, it is passed
through a corn degerminator, which frees the bran and germ and breaks the-endosperm to two or more
pieces. Stock from the degerminator is dried to 14-16% moisture and cooled in revolving or gravity-
type coolers.
The largest endosperm pieces are used for making corn flakes. The stocks are passed through a
hominy separator. It first separates the fine particles and then grades the larger fragments to four sizes
and "polishes" them. The various grades of broken corn are passed through aspirators to remove loose
bran from the endosperm fragments. The corn fragments are reduced to coarse, medium, and fine grits
by gradual reduction between corrugated rolls and subsequent sifting of the stock. The coarsest stock
from the aspirators goes to the first-break rolls. The rolls are spaced further apart, have coarser
corrugations, and operate at lower speed differential than the subsequent breaks. The coarsest grade of
hominy is highly contaminated with germ. The germ is flattened between the break rolls with
minimum endosperm grinding and separated by sieving. The successive steps in the gradual reduction
for corn are similar to those described for wheat. Modern corn mills can produce a variety of grits,
meals, and flours. They are dried at 65ºC and cooled before packing. The flattened germs are used to
produce corn oil. The germ is dried to about 2-3% moisture, ground, tempered with steam, and passed
through expellers. The germ cake from which most of the oil has been expelled is frequently reground
and may be solvent extracted before packaging.
Hominy or grits for industrial uses, such as brewing and manufacture of wallpaper paste, are flaked.
The grits are steamed and passed between heavy-duty heated iron rolls, and the flakes are dried but not
toasted. The heating process gelatinizes the starch.
Yields
Relative yields of mill products depend on whether the main objective is to produce grits or meal and
whether the corn was degermed before grinding. In milling corn for grits and meal by the
degerminating process, the following average yields are obtained: grits 52%, meal and flour 8%,
hominy feed 35%, and crude corn oil 1%. When corn is not degermed before grinding, about 72%
corn meal and 20% feed are produced. Of the total meal produced, about two-thirds contain about
1.4% fat and one-third about 4.7% fat. Typical composition of dry milled products from degermed
maize is listed in Table 17-3. Grits and meal are largely produced from the horny or vitreous
endosperm; they contain less than 1.0% and 1.5% fat, respectively. Flour produced by grinding the
starchy endosperm contains 2-3% fat from broken germ during processing. The large surface area and
relatively high fat content of corn flour lower its shelf life.
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Flour Through 75 Below 0.0095 5
Germ 3-30 0.292-0.0268 14
Hominy feed 11
New-Process Milling
In this process, steel rolls are used as in the milling of wheat. The objective is to remove the bran and
germ and to recover the endosperm in the farm of hominy or corn grits, coarse meal, fine meal, and
corn flour. Corn grits and coarse, meal consist largely of particles of flinty endosperm, and the fine
meal and corn flour are obtained mainly from the soft and starchy endosperm. Flint varieties of corn
are considered too "sharp" for grinding to a meal. Dent corn is almost invariably used. Since the grits
used in the manufacture of corn flakes are made mainly from white corn, large quantities are used to
make grits. Meal and flour are considered as by-products.
The corn is cleaned and passed through a scourer to remove the tip cap from the germ end of the
kernel. The hilar layer under the tip is frequently black, and it causes black specks in the meal. The
corn is tempered by two additions of water to moisture content of 21-24%. Subsequently, it is passed
through a corn degerminator, which frees the bran and germ and breaks the-endosperm to two or more
pieces. Stock from the degerminator is dried to 14-16% moisture and cooled in revolving or gravity-
type coolers.
The largest endosperm pieces are used for making corn flakes. The stocks are passed through a
hominy separator. It first separates the fine particles and then grades the larger fragments to four sizes
and "polishes" them. The various grades of broken corn are passed through aspirators to remove loose
bran from the endosperm fragments. The corn fragments are reduced to coarse, medium, and fine grits
by gradual reduction between corrugated rolls and subsequent sifting of the stock. The coarsest stock
from the aspirators goes to the first-break rolls. The rolls are spaced further apart, have coarser
corrugations, and operate at lower speed differential than the subsequent breaks. The coarsest grade of
hominy is highly contaminated with germ. The germ is flattened between the break rolls with
minimum endosperm grinding and separated by sieving. The successive steps in the gradual reduction
for corn are similar to those described for wheat. Modern corn mills can produce a variety of grits,
meals, and flours. They are dried at 65ºC and cooled before packing. The flattened germs are used to
produce corn oil. The germ is dried to about 2-3% moisture, ground, tempered with steam, and passed
through expellers. The germ cake from which most of the oil has been expelled is frequently reground
and may be solvent extracted before packaging.
Hominy or grits for industrial uses, such as brewing and manufacture of wallpaper paste, are flaked.
The grits are steamed and passed between heavy-duty heated iron rolls, and the flakes are dried but not
toasted. The heating process gelatinizes the starch.
Yields
Relative yields of mill products depend on whether the main objective is to produce grits or meal and
whether the corn was degermed before grinding. In milling corn for grits and meal by the
degerminating process, the following average yields are obtained: grits 52%, meal and flour 8%,
hominy feed 35%, and crude corn oil 1%. When corn is not degermed before grinding, about 72%
corn meal and 20% feed are produced. Of the total meal produced, about two-thirds contain about
1.4% fat and one-third about 4.7% fat. Typical composition of dry milled products from degermed
maize is listed in Table 17-3. Grits and meal are largely produced from the horny or vitreous
endosperm; they contain less than 1.0% and 1.5% fat, respectively. Flour produced by grinding the
starchy endosperm contains 2-3% fat from broken germ during processing. The large surface area and
relatively high fat content of corn flour lower its shelf life.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
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Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 51 of 162
According to the Food and Drug Administration (FDA) standards the fat content of corn meal may not
differ more than 0.3% from that of cleaned corn; that of bolted corn meal should not be less than
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According to the Food and Drug Administration (FDA) standards the fat content of corn meal may not
differ more than 0.3% from that of cleaned corn; that of bolted corn meal should not be less than
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 52 of 162
2.25% or more than 0.3% greater than the fat of cleaned corn; that of degerminated corn meal should
be less than 2.25%; that of corn grits should be not more than 2.25%; and that of corn flour may not
exceed that of cleaned corn.
The meals and flours are produced from maize ground to typical granulations. The cooked flour
hydrates readily in cold water to form a stable paste. The toasted germ is a food-grade product in flake
form; the stabilized product contains all the original oil of the germ. The germ cake is a feed product
from maize germ from which most of the oil has been removed. It is used as a carrier for vitamins and
antibiotics in animal feed formulations.
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2.25% or more than 0.3% greater than the fat of cleaned corn; that of degerminated corn meal should
be less than 2.25%; that of corn grits should be not more than 2.25%; and that of corn flour may not
exceed that of cleaned corn.
The meals and flours are produced from maize ground to typical granulations. The cooked flour
hydrates readily in cold water to form a stable paste. The toasted germ is a food-grade product in flake
form; the stabilized product contains all the original oil of the germ. The germ cake is a feed product
from maize germ from which most of the oil has been removed. It is used as a carrier for vitamins and
antibiotics in animal feed formulations.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 53 of 162
WET MILLING
The main products of wet milling are starch (unmodified and modified, including syrups, and
dextrose) and several coproducts. The coproducts, used mainly as feed ingredients, include gluten
meal, gluten feed, corn germ meal, and condensed, fermented corn extractives (about 50% solids).
Processing maize germ yields refined oil (along with fatty acids from crude oil refining) and corn
germ meal. Steeping in a very dilute solution of sulfur dioxide at 48-52ºC for 30-50 hours first softens
the cleaned corn. For optimum, milling and separation of corn components, at the end of the steeping
period the corn should have absorbed about 45% water, released about 6.0-6.5% of its dry substance
as solubles into the steep water, absorbed about 0.2-0.4g sulfur dioxide per kilogram, and become
quite soft.
When corn has been optimally steeped, the germ can be removed easily and intact; the starch can be
separated from fiber by milling and screening and can easily be removed from the gluten by
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WET MILLING
The main products of wet milling are starch (unmodified and modified, including syrups, and
dextrose) and several coproducts. The coproducts, used mainly as feed ingredients, include gluten
meal, gluten feed, corn germ meal, and condensed, fermented corn extractives (about 50% solids).
Processing maize germ yields refined oil (along with fatty acids from crude oil refining) and corn
germ meal. Steeping in a very dilute solution of sulfur dioxide at 48-52ºC for 30-50 hours first softens
the cleaned corn. For optimum, milling and separation of corn components, at the end of the steeping
period the corn should have absorbed about 45% water, released about 6.0-6.5% of its dry substance
as solubles into the steep water, absorbed about 0.2-0.4g sulfur dioxide per kilogram, and become
quite soft.
When corn has been optimally steeped, the germ can be removed easily and intact; the starch can be
separated from fiber by milling and screening and can easily be removed from the gluten by
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 54 of 162
centrifuging. The corn wet-milling grind in 1983 was 33% high-fructose corn syrup, 21% starch, 21%
ethanol, 19% corn syrup, and 6% dextrose. Coproducts of maize starch wet milling amount to about
one-third of the total output. Except for maize oil and steep liquor (used in industrial fermentations),
the coproducts are mainly sold as feed ingredients. In decreasing value they are corn gluten meal, corn
gluten feed, spent germ meal, corn starch molasses or hydrol, steep liquor (condensed corn
fermentation extractives), corn bran, and hydrolyzed fatty acids.
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centrifuging. The corn wet-milling grind in 1983 was 33% high-fructose corn syrup, 21% starch, 21%
ethanol, 19% corn syrup, and 6% dextrose. Coproducts of maize starch wet milling amount to about
one-third of the total output. Except for maize oil and steep liquor (used in industrial fermentations),
the coproducts are mainly sold as feed ingredients. In decreasing value they are corn gluten meal, corn
gluten feed, spent germ meal, corn starch molasses or hydrol, steep liquor (condensed corn
fermentation extractives), corn bran, and hydrolyzed fatty acids.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
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Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 56 of 162
Corn gluten meal is a high-protein product, used as a protein-balancing ingredient in feed
formulations. It is used widely in broiler and layer rations because of its high content of carotenoid
pigments. Among the three carotene isomers (beta, zeta, and beta-zeta), only beta-carotene has
significant vitamin A activity. The dihydroxy xanthophylls are potent pigments for coloring poultry
skin and egg yolks. The major isomer, lutein, is slightly superior to zeaxanthin in producing color. The
monohydroxy pigments, zeinoxanthin and cryptoxanthin, have less than half the pigmenting value of
the dihydroxy pigments. Xanthophyll levels in gluten meal are highest in winter months and drop
gradually to half the original value by the end of summer.
The linoleic acid content, on as-is basis, is 3.2% in corn gluten meal, 2.2% in corn gluten feed,
and about 0.5% in corn germ meal (Rapp, 1978). Corn gluten meal is relatively rich in xanthophylls
(100-225 mg/lb); 10 mg/lb is present in corn gluten feed, and practically none is present in corn germ
meal and concentrated steepwater. Corn gluten meal contains 30-65 vitamin A equivalents as retinol
(0.15 mg retinol = 5,000 IU vitamin A) and 20-30 mg of beta-carotene per pound.
Maize contains about 4.5% oil, of which 85% is present in the germ. The germ fraction
separated from maize by the wet- milling process contains about 50% oil and by the dry milling
process about 25% oil. Germ oil can be extracted by a continuous screw press (expeller) to yield a
meal with a residual oil content of 7-10%; solvent extraction (directly or following expeller extraction)
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Corn gluten meal is a high-protein product, used as a protein-balancing ingredient in feed
formulations. It is used widely in broiler and layer rations because of its high content of carotenoid
pigments. Among the three carotene isomers (beta, zeta, and beta-zeta), only beta-carotene has
significant vitamin A activity. The dihydroxy xanthophylls are potent pigments for coloring poultry
skin and egg yolks. The major isomer, lutein, is slightly superior to zeaxanthin in producing color. The
monohydroxy pigments, zeinoxanthin and cryptoxanthin, have less than half the pigmenting value of
the dihydroxy pigments. Xanthophyll levels in gluten meal are highest in winter months and drop
gradually to half the original value by the end of summer.
The linoleic acid content, on as-is basis, is 3.2% in corn gluten meal, 2.2% in corn gluten feed,
and about 0.5% in corn germ meal (Rapp, 1978). Corn gluten meal is relatively rich in xanthophylls
(100-225 mg/lb); 10 mg/lb is present in corn gluten feed, and practically none is present in corn germ
meal and concentrated steepwater. Corn gluten meal contains 30-65 vitamin A equivalents as retinol
(0.15 mg retinol = 5,000 IU vitamin A) and 20-30 mg of beta-carotene per pound.
Maize contains about 4.5% oil, of which 85% is present in the germ. The germ fraction
separated from maize by the wet- milling process contains about 50% oil and by the dry milling
process about 25% oil. Germ oil can be extracted by a continuous screw press (expeller) to yield a
meal with a residual oil content of 7-10%; solvent extraction (directly or following expeller extraction)
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 57 of 162
produces a meal with a residual oil content of 1-3%. About 1.75 lb of oil can be recovered from a
bushel of maize by solvent extraction of the germ.
CORN SWEETENERS
Production of Com Syrup
The manufacture of corn sweeteners is a multistep continuous process. To convert the starch
granules in the slurry to corn syrup, the granules must be gelatinized and the starch depolymerized in a
conversion process that is halted as soon as the desired composition is reached. Two or more
interrelated processes may be involved. Thus, for instance, an acid primary conversion may be
followed by an enzymic conversion. The products of the conversion may be used in the production of
isomerized corn syrups. The starch conversion products are classified by their dextrose equivalent
DE. This is a measure of the reducing sugar content calculated as anhydrous dextrose and
expressed as a percentage of total dry substance. DE is a useful parameter in classifying corn
syrups, but it does not provide full information on actual composition.
While the most common methods used in the production of corn syrup are the acid and acid-
enzyme processes, multiple enzyme processes produce some syrups. In the acid conversion process,
starch slurry of about 35-40% dry matter is acidified with hydrochloric acid to pH of about 2 and
pumped to a converter. In the converter, the steam pressure is adjusted to about 30 lb/sq in. and the
starch is gelatinized and depolymerized to a predetermined level. Adjusting the pH to 4-5 with an
alkali terminates the process. The liquor is clarified by filtration and/or centrifugation and is
concentrated by evaporation until it contains about 60% dry matter. The syrup is further clarified and
decolorized by treatment with powdered and/or granular carbon, refined by ion exchange to remove
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produces a meal with a residual oil content of 1-3%. About 1.75 lb of oil can be recovered from a
bushel of maize by solvent extraction of the germ.
CORN SWEETENERS
Production of Com Syrup
The manufacture of corn sweeteners is a multistep continuous process. To convert the starch
granules in the slurry to corn syrup, the granules must be gelatinized and the starch depolymerized in a
conversion process that is halted as soon as the desired composition is reached. Two or more
interrelated processes may be involved. Thus, for instance, an acid primary conversion may be
followed by an enzymic conversion. The products of the conversion may be used in the production of
isomerized corn syrups. The starch conversion products are classified by their dextrose equivalent
DE. This is a measure of the reducing sugar content calculated as anhydrous dextrose and
expressed as a percentage of total dry substance. DE is a useful parameter in classifying corn
syrups, but it does not provide full information on actual composition.
While the most common methods used in the production of corn syrup are the acid and acid-
enzyme processes, multiple enzyme processes produce some syrups. In the acid conversion process,
starch slurry of about 35-40% dry matter is acidified with hydrochloric acid to pH of about 2 and
pumped to a converter. In the converter, the steam pressure is adjusted to about 30 lb/sq in. and the
starch is gelatinized and depolymerized to a predetermined level. Adjusting the pH to 4-5 with an
alkali terminates the process. The liquor is clarified by filtration and/or centrifugation and is
concentrated by evaporation until it contains about 60% dry matter. The syrup is further clarified and
decolorized by treatment with powdered and/or granular carbon, refined by ion exchange to remove
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 58 of 162
soluble minerals and proteins and to deodorize and decolorize, and further concentrated in large
vacuum pans or continuous evaporators. In the acid-enzyme process, the liquor containing a partially
converted product is treated with an appropriate enzyme or combination of enzymes to complete the
conversion. Thus, in the production of 42-DE high maltose syrup, the acid conversion is carried
through until dextrose production is negligible. At this point, beta-amylase (a maltose-producing
enzyme) is added and the conversion is continued. The enzyme is deactivated, and the purification and
concentration are continued as in the acid process.
In enzyme-enzyme processes, the starch granules are cooked, preliminary starch
depolymerization is done by starch-liquefying alpha-amylase, and a single enzyme or a combination of
enzymes does the final depolymerization. Combinations of enzymes make possible the production of
syrups with specific composition and/or properties, such as high-maltose or high fermentable syrups.
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soluble minerals and proteins and to deodorize and decolorize, and further concentrated in large
vacuum pans or continuous evaporators. In the acid-enzyme process, the liquor containing a partially
converted product is treated with an appropriate enzyme or combination of enzymes to complete the
conversion. Thus, in the production of 42-DE high maltose syrup, the acid conversion is carried
through until dextrose production is negligible. At this point, beta-amylase (a maltose-producing
enzyme) is added and the conversion is continued. The enzyme is deactivated, and the purification and
concentration are continued as in the acid process.
In enzyme-enzyme processes, the starch granules are cooked, preliminary starch
depolymerization is done by starch-liquefying alpha-amylase, and a single enzyme or a combination of
enzymes does the final depolymerization. Combinations of enzymes make possible the production of
syrups with specific composition and/or properties, such as high-maltose or high fermentable syrups.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
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Types of Com Sweeteners
There are five types of corn sweeteners.
Corn syrup (glucose syrup) is the purified concentrated aqueous solution of saccharides
obtained from edible starch. It has a DE of 20 or more.
Dried corn syrup (dried glucose syrup) is corn syrup from which the water has been partially
removed. Refined corn syrups are spray or vacuum drum- dried to low moisture content, and they
form granular, crystalline, or powdery amorphous products. They are mildly sweet and moderately
hygroscopic. Because of their hygroscopicity, they are packed in multiwall, moisture-proof paper
bags. The products are comparable in chemical composition to their liquid corn syrups, except for
lower moisture contents.
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Types of Com Sweeteners
There are five types of corn sweeteners.
Corn syrup (glucose syrup) is the purified concentrated aqueous solution of saccharides
obtained from edible starch. It has a DE of 20 or more.
Dried corn syrup (dried glucose syrup) is corn syrup from which the water has been partially
removed. Refined corn syrups are spray or vacuum drum- dried to low moisture content, and they
form granular, crystalline, or powdery amorphous products. They are mildly sweet and moderately
hygroscopic. Because of their hygroscopicity, they are packed in multiwall, moisture-proof paper
bags. The products are comparable in chemical composition to their liquid corn syrups, except for
lower moisture contents.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
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Maltodextrin is a purified, concentrated, aqueous solution of saccharides or the dried product
derived from the solution obtained from starch. It has DE of less than 20. Maltodextrins are produced
in the same manner as corn syrups except that the conversion process is stopped at an early stage to
keep the DE below 20. Both acid and enzyme processes can be used. Maltodextrins are usually dried
to white, free-flowing powders and are packed in multiwall bags. However, in some cases, moderately
concentrated solutions of maltodextrins are sold.
Dextrose monohydrate is purified and crystallized (D-glucose containing one molecule of
water of crystallization per molecule of D-glucose. For the manufacture of dextrose, complete
depolymerization of the starch substrate and recovery of the product by crystallization are required.
The starch slurry is gelatinized as in the manufacture of corn syrup and is partially converted by acid
or alpha-amylase. Then a purified glucoamylase enzyme, free of transglucosylase activity, is added to
the intermediate substrate. When the dextrose conversion is complete, the enzyme is deactivated and
the dextrose liquor is filtered to remove residual suspended materials and purified and decolorized
with granular or powdered carbon.
The liquor is concentrated to about 75% solids, cooled, and pumped into crystallizers. The
temperature is slowly lowered to about 25ºC. Crystallization is induced by seed crystals left in the
crystallizer from the previous batch. Dextrose monohydrate crystallizes from the mother liquor, is
separated by centrifugation, and is washed in the centrifuges with a spray of water. The wet crystals
are dried in warm air to about 8.5% moisture. The mother liquor is reconverted, refined again,
concentrated, and crystallized to produce a second crop of dextrose hydrate.
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Maltodextrin is a purified, concentrated, aqueous solution of saccharides or the dried product
derived from the solution obtained from starch. It has DE of less than 20. Maltodextrins are produced
in the same manner as corn syrups except that the conversion process is stopped at an early stage to
keep the DE below 20. Both acid and enzyme processes can be used. Maltodextrins are usually dried
to white, free-flowing powders and are packed in multiwall bags. However, in some cases, moderately
concentrated solutions of maltodextrins are sold.
Dextrose monohydrate is purified and crystallized (D-glucose containing one molecule of
water of crystallization per molecule of D-glucose. For the manufacture of dextrose, complete
depolymerization of the starch substrate and recovery of the product by crystallization are required.
The starch slurry is gelatinized as in the manufacture of corn syrup and is partially converted by acid
or alpha-amylase. Then a purified glucoamylase enzyme, free of transglucosylase activity, is added to
the intermediate substrate. When the dextrose conversion is complete, the enzyme is deactivated and
the dextrose liquor is filtered to remove residual suspended materials and purified and decolorized
with granular or powdered carbon.
The liquor is concentrated to about 75% solids, cooled, and pumped into crystallizers. The
temperature is slowly lowered to about 25ºC. Crystallization is induced by seed crystals left in the
crystallizer from the previous batch. Dextrose monohydrate crystallizes from the mother liquor, is
separated by centrifugation, and is washed in the centrifuges with a spray of water. The wet crystals
are dried in warm air to about 8.5% moisture. The mother liquor is reconverted, refined again,
concentrated, and crystallized to produce a second crop of dextrose hydrate.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
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Dextrose anhydrous is purified and crystallized D-glucose without water of crystallization.
Redissolving dextrose hydrate and refining the solution to a highly purified and clear filtrate obtain
anhydrous dextrose. The solution is evaporated to high solids content, and crystallizing at an elevated
temperature precipitates anhydrous α-D Glucose. The anhydrous crystals are separated by
centrifugation, washed with a warm water spray, and dried. Anhydrous dextrose can be made by direct
crystallization from high-DE liquor.
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Dextrose anhydrous is purified and crystallized D-glucose without water of crystallization.
Redissolving dextrose hydrate and refining the solution to a highly purified and clear filtrate obtain
anhydrous dextrose. The solution is evaporated to high solids content, and crystallizing at an elevated
temperature precipitates anhydrous α-D Glucose. The anhydrous crystals are separated by
centrifugation, washed with a warm water spray, and dried. Anhydrous dextrose can be made by direct
crystallization from high-DE liquor.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125052. e-mail- [email protected] Page 62 of
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162
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125052.
E-mail- [email protected]
BARLEY
E-mail- [email protected]
BARLEY
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125052.
E-mail- [email protected]
E-mail- [email protected]
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125052.
E-mail- [email protected]
Composition in Percent of Milled Barley and Products of Barley Milling
Product MoistureProteinFatN-Free ExtractCrude FiberAsh
Dehulled Barley 12.5 10.61.7 72.1 1.61.5
Pearls 12.5 7.81.0 76.2 1.41.1
Pearling Dust 12.5 9.51.4 74.3 0.81.5
Feedmeal 12.0 12.52.0 64.0 5.03.5
Bran 10.5 14.03.5 57.1 10.04.9
Husks 10.4 3.61.0 49.2 28.67.2
Composition in Percent of Typical Barley Products
Barley ProductMoistureProteinFatCrude FiberAsh
Dehulled Barley 12.5 10.61.7 1.61.5
Pearls 12.5 7.81.0 1.41.1
Pearling Dust 12.5 9.51.4 0.81.5
Feedmeal 12.0 12.52.0 5.03.5
Bran 10.5 14.03.5 10.04.9
Husks 10.4 3.61.0 28.67.2
Composition of Barley
On a dry-matter basis, covered barley contains 63-65% starch, 1-2% sucrose, about 1%
other sugars, 1-1.5% soluble gums, 8-10% hemicellulose, 2-3% lipids, 8-10% protein (N x
6.25), 2-2.3% ash, and 5-6% other components. In regular barley, the linear starch component
(amylose) comprises 24% of the total starch.
The proteins in barley are composed of four groups varying in solubility. The albumin
fraction comprises less than 10% of the proteins, the globulins about 20%, the hordeins
(soluble in 70% alcohol) 30%; the remaining 40% of the proteins are glutelins. About one-half
of the amino acid residues in hordeins are either glutamine or proline; the amounts of aspartic
acid, glycine, and lysine are small. The amino acid composition of the glutelins resembles that of
hordeins.
Barley lipids are concentrated in the embryo and the aleurone layer. Although the whole
grain has only 2% petroleum ether extractable components, isolated embryos contain 15% lipids.
Mature barley may contain over 2% of fructosans. Unlike starch, which is restricted to
the starchy endosperm, the fructosans are distributed throughout the grain. Sucrose is virtually
restricted to the embryo and aleurone; it represents 12-15% of the embryo but only 1-2% of the
whole grain. Raffinose is also a major embryo constituent-about 5% of the dry weight. The husks
contain over two-thirds of the grain's cellulose; the cell walls of the starchy endosperm lack true
cellulose.
The following are some typical brewing figures:
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Composition in Percent of Milled Barley and Products of Barley Milling
Product MoistureProteinFatN-Free ExtractCrude FiberAsh
Dehulled Barley 12.5 10.61.7 72.1 1.61.5
Pearls 12.5 7.81.0 76.2 1.41.1
Pearling Dust 12.5 9.51.4 74.3 0.81.5
Feedmeal 12.0 12.52.0 64.0 5.03.5
Bran 10.5 14.03.5 57.1 10.04.9
Husks 10.4 3.61.0 49.2 28.67.2
Composition in Percent of Typical Barley Products
Barley ProductMoistureProteinFatCrude FiberAsh
Dehulled Barley 12.5 10.61.7 1.61.5
Pearls 12.5 7.81.0 1.41.1
Pearling Dust 12.5 9.51.4 0.81.5
Feedmeal 12.0 12.52.0 5.03.5
Bran 10.5 14.03.5 10.04.9
Husks 10.4 3.61.0 28.67.2
Composition of Barley
On a dry-matter basis, covered barley contains 63-65% starch, 1-2% sucrose, about 1%
other sugars, 1-1.5% soluble gums, 8-10% hemicellulose, 2-3% lipids, 8-10% protein (N x
6.25), 2-2.3% ash, and 5-6% other components. In regular barley, the linear starch component
(amylose) comprises 24% of the total starch.
The proteins in barley are composed of four groups varying in solubility. The albumin
fraction comprises less than 10% of the proteins, the globulins about 20%, the hordeins
(soluble in 70% alcohol) 30%; the remaining 40% of the proteins are glutelins. About one-half
of the amino acid residues in hordeins are either glutamine or proline; the amounts of aspartic
acid, glycine, and lysine are small. The amino acid composition of the glutelins resembles that of
hordeins.
Barley lipids are concentrated in the embryo and the aleurone layer. Although the whole
grain has only 2% petroleum ether extractable components, isolated embryos contain 15% lipids.
Mature barley may contain over 2% of fructosans. Unlike starch, which is restricted to
the starchy endosperm, the fructosans are distributed throughout the grain. Sucrose is virtually
restricted to the embryo and aleurone; it represents 12-15% of the embryo but only 1-2% of the
whole grain. Raffinose is also a major embryo constituent-about 5% of the dry weight. The husks
contain over two-thirds of the grain's cellulose; the cell walls of the starchy endosperm lack true
cellulose.
The following are some typical brewing figures:
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125052.
E-mail- [email protected]
Specific gravity of beer 1.012
Original extract of wort (solids before fermentation) 12.0%
Apparent extract of beer (Balling or Plato) 3.3%
Real attenuation (fermented solids) 7.0%
Alcohol (by volume) 4.4%
Extract, fermented 58.2%
Sugars in original extract (% of total) 66.5%
Amylodextrins traces
A typical beer in the United States contains in addition to 90% water, 45 alcohol, 4%
carbohydrates, 0.8% inorganic salts, 0.3% nitrogenous com pounds, 0.2% organic acids, 0-5%
CO2, and 0.2% other compound.
The principal uses of barley are as feed for animals particularly pigs, in the form of
barley meal for malting and brewing in the manufacture of beer and for distilling in whiskey
manufacture. Barley finds little use for human food in Europe and North America, but is widely
used for this purpose in Asian countries. Even there, however, its use for human, food is
declining as preferred grains become more plentiful.
Beer: Beer is made by yeast fermentation of a sugary solution called wort, which also
contains nitrogenous substances, vitamins and trace elements necessary for growth of the yeast.
The manufacture of beer from barley comprises two major processes: malting and brewing.
Malting is a controlled germination process, which produces a complement of enzymes,
which are able to convert cereal starches to fermentable sugars, to secure an adequate supply of
amino acids and other minor nutrients for yeasts, and to modify and quality of the
macromolecules, which have such important effects on the physical quality of beer.
Brewing is the process of converting the starch to an alcoholic solution, by means of
yeast fermentation. About 75% of the original starch is converted to alcohol.
Malting: The condition of barley for malting has a considerable effect on the yield and quality
of the products. Besides varietal and species purity and satisfactory grain colour, malting barley
should be of good bacteriological quality of beer.
More specific characteristics of barley for malting and brewing are:
1.High germination capacity and energy, with adequate enzymic activity.
2.Absence of de-husked or broken grains, and of grains mechanically damaged in
threshing.
3. Capacity of grains modified by malting, to produce a maximum of extract when
mashed
4. Low content of husk.
5.Low protein (1.35-1.75% N content) and high starch content
Comparative Ranges in Composition of Barley and Malt
Property Barley Malt
(Brewers’ and Distillers’)
Kernel Weight (mg) 32-36 29-33
Moisture (%) 10-14 4-6
Starch (%) 55-60 50-55
Sugars (%) 0.5-1.0 8-10
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Specific gravity of beer 1.012
Original extract of wort (solids before fermentation) 12.0%
Apparent extract of beer (Balling or Plato) 3.3%
Real attenuation (fermented solids) 7.0%
Alcohol (by volume) 4.4%
Extract, fermented 58.2%
Sugars in original extract (% of total) 66.5%
Amylodextrins traces
A typical beer in the United States contains in addition to 90% water, 45 alcohol, 4%
carbohydrates, 0.8% inorganic salts, 0.3% nitrogenous com pounds, 0.2% organic acids, 0-5%
CO2, and 0.2% other compound.
The principal uses of barley are as feed for animals particularly pigs, in the form of
barley meal for malting and brewing in the manufacture of beer and for distilling in whiskey
manufacture. Barley finds little use for human food in Europe and North America, but is widely
used for this purpose in Asian countries. Even there, however, its use for human, food is
declining as preferred grains become more plentiful.
Beer: Beer is made by yeast fermentation of a sugary solution called wort, which also
contains nitrogenous substances, vitamins and trace elements necessary for growth of the yeast.
The manufacture of beer from barley comprises two major processes: malting and brewing.
Malting is a controlled germination process, which produces a complement of enzymes,
which are able to convert cereal starches to fermentable sugars, to secure an adequate supply of
amino acids and other minor nutrients for yeasts, and to modify and quality of the
macromolecules, which have such important effects on the physical quality of beer.
Brewing is the process of converting the starch to an alcoholic solution, by means of
yeast fermentation. About 75% of the original starch is converted to alcohol.
Malting: The condition of barley for malting has a considerable effect on the yield and quality
of the products. Besides varietal and species purity and satisfactory grain colour, malting barley
should be of good bacteriological quality of beer.
More specific characteristics of barley for malting and brewing are:
1.High germination capacity and energy, with adequate enzymic activity.
2.Absence of de-husked or broken grains, and of grains mechanically damaged in
threshing.
3. Capacity of grains modified by malting, to produce a maximum of extract when
mashed
4. Low content of husk.
5.Low protein (1.35-1.75% N content) and high starch content
Comparative Ranges in Composition of Barley and Malt
Property Barley Malt
(Brewers’ and Distillers’)
Kernel Weight (mg) 32-36 29-33
Moisture (%) 10-14 4-6
Starch (%) 55-60 50-55
Sugars (%) 0.5-1.0 8-10
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125052.
E-mail- [email protected]
Total N (%) 1.8-2.3 1.8-2.3
Soluble N (% of total) 10-12 35-50
Diastatic Power (°L) 50-60 100-250
Alpha- amylase (20° units)* Trace 30-60
Proteolytic Activity** Trace 15-30
* 20°C dextrinzing units, a unit of alpha- amylase activity
**Arbitrary units
Malting operations
The sequence of operations in malting is as follows.
1.Kiln drying
2.Screening (cleaning the grain)
3.Storage
4.Steeping
5.Draining
6.Spreading on malting floor
7.Turning or ploughing
8.Drying in malt kilns
9.Screening (removal of malt culms).
1.The grain is first dried in a kiln or drum drier to between 10% and 14% moisture content,
at this moisture content the grain can be safely stored.
2.The cleaning process embodies machinery operating on principles similar to those used
in, wheat cleaning.
3.After drying and cleaning, the grain is stored in bulk for at least 3 weeks before malting.
4.The malting process proper begins when the barley grain is steeped in water. Time
required for steeping depends on temperature and degree of aeration of the steep water. A
temperature of 10-20ºC is recommended, with steeping times of 40-60 h in the UK. 50-80
h on the continent. The object of malting is to provide the conditions in which natural
germination can proceed until the optimum enzymic activity has been developed.
5 6 &7. After steeping, the surplus water is drained off from the grain, which is then spread
on the malting floor in heaps or 'couches' for a period of time while germination takes place.
During this time the plumule grows to one-half to two-thirds the length of the grain, an
extensive root system develops, and modification of the endosperm proceeds.
Modification starts when the growing embryo secretes gibberellic acid, a hormone, which in
turn triggers the production of enzymes, which alter the structure of the endosperm. These
enzymes include B-glucanases, B- oligosaccharidases and pentosanases which dissolve the
material binding the endosperm cell walls and help to liberate the starch granules contained in
the endosperm cells. Other enzymes that become active in the early stages include phosphatase,
phytase, hemicellulase and protease. Amylases become active at a later stage. Accompanying the
increased enzymic activity there is a considerable increase in the rate of respiration of the
grain-the process in which starchy materials are converted (via sugar) to carbon dioxide and
water, The respiratory loss of dry matter during malting is generally 5-9%, depending on the
length of time the grain remains on the malting floor. The loss is minimized when germination is
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Total N (%) 1.8-2.3 1.8-2.3
Soluble N (% of total) 10-12 35-50
Diastatic Power (°L) 50-60 100-250
Alpha- amylase (20° units)* Trace 30-60
Proteolytic Activity** Trace 15-30
* 20°C dextrinzing units, a unit of alpha- amylase activity
**Arbitrary units
Malting operations
The sequence of operations in malting is as follows.
1.Kiln drying
2.Screening (cleaning the grain)
3.Storage
4.Steeping
5.Draining
6.Spreading on malting floor
7.Turning or ploughing
8.Drying in malt kilns
9.Screening (removal of malt culms).
1.The grain is first dried in a kiln or drum drier to between 10% and 14% moisture content,
at this moisture content the grain can be safely stored.
2.The cleaning process embodies machinery operating on principles similar to those used
in, wheat cleaning.
3.After drying and cleaning, the grain is stored in bulk for at least 3 weeks before malting.
4.The malting process proper begins when the barley grain is steeped in water. Time
required for steeping depends on temperature and degree of aeration of the steep water. A
temperature of 10-20ºC is recommended, with steeping times of 40-60 h in the UK. 50-80
h on the continent. The object of malting is to provide the conditions in which natural
germination can proceed until the optimum enzymic activity has been developed.
5 6 &7. After steeping, the surplus water is drained off from the grain, which is then spread
on the malting floor in heaps or 'couches' for a period of time while germination takes place.
During this time the plumule grows to one-half to two-thirds the length of the grain, an
extensive root system develops, and modification of the endosperm proceeds.
Modification starts when the growing embryo secretes gibberellic acid, a hormone, which in
turn triggers the production of enzymes, which alter the structure of the endosperm. These
enzymes include B-glucanases, B- oligosaccharidases and pentosanases which dissolve the
material binding the endosperm cell walls and help to liberate the starch granules contained in
the endosperm cells. Other enzymes that become active in the early stages include phosphatase,
phytase, hemicellulase and protease. Amylases become active at a later stage. Accompanying the
increased enzymic activity there is a considerable increase in the rate of respiration of the
grain-the process in which starchy materials are converted (via sugar) to carbon dioxide and
water, The respiratory loss of dry matter during malting is generally 5-9%, depending on the
length of time the grain remains on the malting floor. The loss is minimized when germination is
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125052.
E-mail- [email protected]
rapid and uniform. Starch is the most valuable portion of the grain, and a long time on the
malting floor involves greater starch loss.
The degree of modification required depends on the type of beer brewed. Less modification
is required in grain for pale ale than for dark ale.
8. When the grain has been modified sufficiently, it is dried to 2% moisture content in a
malt kiln, first at a low temperature and later at a temperature high enough to suspend enzymic
activity without destroying the enzymes.
9 Finally, the dried grain is screened to remove the rootlets-called malt culms, which are
now dry and brittle. The culms amount to 3-5 % of the products. The screened product is malt.
Brewing
The sequence of operations in brewing is as follows:
1.Grinding of malt
2.Steeping
3.Filtering
4.Sparging
5.Flavouring
6.Boiling
7.Filtering
8.Seeding with yeast
9.Fermenting
10.Removal of yeast
11.Sterilization
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rapid and uniform. Starch is the most valuable portion of the grain, and a long time on the
malting floor involves greater starch loss.
The degree of modification required depends on the type of beer brewed. Less modification
is required in grain for pale ale than for dark ale.
8. When the grain has been modified sufficiently, it is dried to 2% moisture content in a
malt kiln, first at a low temperature and later at a temperature high enough to suspend enzymic
activity without destroying the enzymes.
9 Finally, the dried grain is screened to remove the rootlets-called malt culms, which are
now dry and brittle. The culms amount to 3-5 % of the products. The screened product is malt.
Brewing
The sequence of operations in brewing is as follows:
1.Grinding of malt
2.Steeping
3.Filtering
4.Sparging
5.Flavouring
6.Boiling
7.Filtering
8.Seeding with yeast
9.Fermenting
10.Removal of yeast
11.Sterilization
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125052.
E-mail- [email protected]
Barley
Scalper
Storage
Barley
Cleaner
Barley
Separator
Barley
Grader
Small
Kernels
Medium
Kernels
Large
Kernels
Separately Processed
Steep Tank
Germinator (Drum or Compartment
Type)
Drying Kiln
Cleaner
Storage
Dust &
Chaff
Dust, Chaff,
Corn & Weed
Seeds
Oat, Wheat,
Cracked Barley,
etc.
Under Sized
Kernels
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Barley
Scalper
Storage
Barley
Cleaner
Barley
Separator
Barley
Grader
Small
Kernels
Medium
Kernels
Large
Kernels
Separately Processed
Steep Tank
Germinator (Drum or Compartment
Type)
Drying Kiln
Cleaner
Storage
Dust &
Chaff
Dust, Chaff,
Corn & Weed
Seeds
Oat, Wheat,
Cracked Barley,
etc.
Under Sized
Kernels
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125052.
E-mail- [email protected]
Vedpal Yadav, Lecturer in Food Technology, Govt. Polytechnic, Mandi Adampur, Hisar, Haryana, I ndia-125052
Removal of
Malt Culms
up to 85°C
4%
Temperature
Moisture
Kiln drying
5 days
12-16°C
Time
Temperature
Germination
45% Moisture Steeping
12-14%
12°C
Moisture
Temperature
Storage
MILLING OF BARLEY
Barley is milled to make blocked barley, pearl barley, barley groats barley flakes and
barley flour for human consumption. Removal of the hull or husk of barley, which is largely
indigestible, is an important part of the milling process.
Intrinsic qualities: Good quality in barley for milling implies absence of sprouting,
absence of discoloration due to weathering, freedom from fungal attack and insect infestation or
damage, soundness of appearance and absence of undesirable arorna or flavour.
For milling purposes, the harder types are preferred, as the objective is generally not to
produce flour but to remove the hull and bran by superficial abrasion, yielding particles, which
retain the shape of the whole grain. With this kind of processing, softer grains would tend to
fragment leading to a reduction in the yield of first quality products. Barley for milling should
have as low a hull content as possible.
The presence of damaged grains lowers the quality of milled barley. Such grains
frequently reveal areas of exposed endosperm where fungal attack may occur leading to
discoloration. Such grains would contribute discolored particles to the finished product. Thin
grains also lower the milling quality with a higher hull content than normal; they make a small
contribution to the yield of milled product.
Operations: The sequence of operations in barley milling may be summarized as
follows:
Flow Diagram of Malt Production
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Vedpal Yadav, Lecturer in Food Technology, Govt. Polytechnic, Mandi Adampur, Hisar, Haryana, I ndia-125052
Removal of
Malt Culms
up to 85°C
4%
Temperature
Moisture
Kiln drying
5 days
12-16°C
Time
Temperature
Germination
45% Moisture Steeping
12-14%
12°C
Moisture
Temperature
Storage
MILLING OF BARLEY
Barley is milled to make blocked barley, pearl barley, barley groats barley flakes and
barley flour for human consumption. Removal of the hull or husk of barley, which is largely
indigestible, is an important part of the milling process.
Intrinsic qualities: Good quality in barley for milling implies absence of sprouting,
absence of discoloration due to weathering, freedom from fungal attack and insect infestation or
damage, soundness of appearance and absence of undesirable arorna or flavour.
For milling purposes, the harder types are preferred, as the objective is generally not to
produce flour but to remove the hull and bran by superficial abrasion, yielding particles, which
retain the shape of the whole grain. With this kind of processing, softer grains would tend to
fragment leading to a reduction in the yield of first quality products. Barley for milling should
have as low a hull content as possible.
The presence of damaged grains lowers the quality of milled barley. Such grains
frequently reveal areas of exposed endosperm where fungal attack may occur leading to
discoloration. Such grains would contribute discolored particles to the finished product. Thin
grains also lower the milling quality with a higher hull content than normal; they make a small
contribution to the yield of milled product.
Operations: The sequence of operations in barley milling may be summarized as
follows:
Flow Diagram of Malt Production
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125052.
E-mail- [email protected]
Pearl barley
1.Preliminary cleaning
2.Conditioning
3.Bleaching (not practiced in Britain)
4.Blocking
5.Aspiration to remove husk
6.Size-grading by sifting
7.Cutting on groat cutter for barley groats
8.Pearling of blocked barley or large barley groats
9.Aspiration, grading, sifting
10.Polishing
Barley flakes
1.Pre-damping of barley groats
2.Steam cooking of barley groats or pearl barley
3.Flaking on flaking rolls
4.Drying flasks on hot-air drier Barley flour
5.Roller-milling of pearl or blocked barley
Barley flour
1.Barley is cleaned on machines similar to those used for wheat cleaning, viz. milling
separators, indented discs, and aspirators.
2.Conditioning consists in adjustment of moisture content to about 15% by drying or
damping and resting for 24 hr.
3.Bleaching: The beaching of barley is not permitted by law in Britain, but is generally
practiced in Germany Imported barley is preferred to domestic grain for milling In
Germany because of its greater hardness and yielding capacity, and it is the foreign
barley, the aleurone of which has a bluish colour, which is said to require bleaching.
Blocked barley (or occasionally whole barley) is fed into a vertical fireclay or
earthenware cylinder into which steam and sulphur dioxide are injected. The quantities used are
1-2% of moisture (from the steam) and about 0.04% of sulphur dioxide (equivalent to 0.02% of
S). After this treatment, which takes 20-30 minutes, the barley is binned for 12-24 h for the
bleaching to take effect.
4.Blocking and pearling: Both blocking (shelling) and pearling (rounding) of barley
are abrasive scouring processes, differing from each other merely in degree of
removal of the superficial layers of the grain. Blocking removes part of the husk: this
process must be accomplished with the minimum of injury to the kernels; pearling,
carried out in two stages removes the remainder to the husk and part of the
endosperm. The products of these processes are blocked barley, seconds, and pearl
barley, respectively. The three processes remove about 5%, 15% and 11%,
respectively, to yield a final product about 67% of the grain.
Three types of blocking and pearling machine are in general use
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Pearl barley
1.Preliminary cleaning
2.Conditioning
3.Bleaching (not practiced in Britain)
4.Blocking
5.Aspiration to remove husk
6.Size-grading by sifting
7.Cutting on groat cutter for barley groats
8.Pearling of blocked barley or large barley groats
9.Aspiration, grading, sifting
10.Polishing
Barley flakes
1.Pre-damping of barley groats
2.Steam cooking of barley groats or pearl barley
3.Flaking on flaking rolls
4.Drying flasks on hot-air drier Barley flour
5.Roller-milling of pearl or blocked barley
Barley flour
1.Barley is cleaned on machines similar to those used for wheat cleaning, viz. milling
separators, indented discs, and aspirators.
2.Conditioning consists in adjustment of moisture content to about 15% by drying or
damping and resting for 24 hr.
3.Bleaching: The beaching of barley is not permitted by law in Britain, but is generally
practiced in Germany Imported barley is preferred to domestic grain for milling In
Germany because of its greater hardness and yielding capacity, and it is the foreign
barley, the aleurone of which has a bluish colour, which is said to require bleaching.
Blocked barley (or occasionally whole barley) is fed into a vertical fireclay or
earthenware cylinder into which steam and sulphur dioxide are injected. The quantities used are
1-2% of moisture (from the steam) and about 0.04% of sulphur dioxide (equivalent to 0.02% of
S). After this treatment, which takes 20-30 minutes, the barley is binned for 12-24 h for the
bleaching to take effect.
4.Blocking and pearling: Both blocking (shelling) and pearling (rounding) of barley
are abrasive scouring processes, differing from each other merely in degree of
removal of the superficial layers of the grain. Blocking removes part of the husk: this
process must be accomplished with the minimum of injury to the kernels; pearling,
carried out in two stages removes the remainder to the husk and part of the
endosperm. The products of these processes are blocked barley, seconds, and pearl
barley, respectively. The three processes remove about 5%, 15% and 11%,
respectively, to yield a final product about 67% of the grain.
Three types of blocking and pearling machine are in general use
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125052.
E-mail- [email protected]
1) Batch machine consisting of a large circular stone, faced with emergy-cement
composition, and rotating on a horizontal axis within a perforated metal cage.
2) A continuous-working machine of Swedish make consisting of a rotor faced
with abrasive material rotating on a horizontal axis within in semicircular stator
lined with the same material, the distance between rotor and stator being
adjustable
3) A continuous-working machine comprising a pile of small circular stones
rotating on a vertical axis within a metal sleeve, the annular space between the
stones and the sleeve, occupied by the barley, being strongly aspirated.
5-9 Aspiration of the blocked or pearled grain to remove the abraded portions, and
cutting of the blocked barley into portions known as grits.
10.The pearl barley is polished on machines similar to those used for pearling, but
equipped with stones made of hard white sandstone instead of emery composition.
The average yield of pearl barley is 67% of the whole barley.
11-14. Barley flakes are inside from pearl barley by steaming and flaking on large-
diameter smooth rolls. The flakes are dried to about 10.5% moisture content before
packing.
Pearl barley is used for soups and dressings and for the manufacture of puffed barley, a
ready-to-eat breakfast cereal. Pearl barley is also a starting material for manufacture of barley
flour. Milled barley products are also used for extruded food snacks, as croutons in soup and
salad dressings, as crunches for nut substitutes.
BARLEY FLOUR
Barley flour is milled from pearl barley, blocked barley or unpearled hull-less barley.
Optimum tempering conditions are 13% moisture content for 48 h for pearl barley, 14% moisture
content for 48 h for unpearled hull-less barley. The milling system uses roller mills with fluted
and smooth rolls, and plan sifters,
When blocked barley or whole barley is used for milling barley flour, due allowance
must be made for the greatly increased quantity of by-products, which would otherwise choke
the system. Barley flour is also a by-product of the cutting, pearling and polishing processes.
Average extraction rate of 92% of barley flour is obtained from pearl barley representing 67% of
the grain, i.e. an overall extraction rate 55% based on the original whole grain. By using blocked
barley, an overall extraction rate of 59% on the whole grain could be obtained but the product
would be considerably less pure than that milled from pearl barley.
Barley flour is used in the manufacture of flat bread, for infant foods and for food
specialties. It is also a component of composite flours used for risking yeast-raised bread.
Pre-gelatinized barley flour, which has high absorbent properties, provides a good binder and
thickener.
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1) Batch machine consisting of a large circular stone, faced with emergy-cement
composition, and rotating on a horizontal axis within a perforated metal cage.
2) A continuous-working machine of Swedish make consisting of a rotor faced
with abrasive material rotating on a horizontal axis within in semicircular stator
lined with the same material, the distance between rotor and stator being
adjustable
3) A continuous-working machine comprising a pile of small circular stones
rotating on a vertical axis within a metal sleeve, the annular space between the
stones and the sleeve, occupied by the barley, being strongly aspirated.
5-9 Aspiration of the blocked or pearled grain to remove the abraded portions, and
cutting of the blocked barley into portions known as grits.
10.The pearl barley is polished on machines similar to those used for pearling, but
equipped with stones made of hard white sandstone instead of emery composition.
The average yield of pearl barley is 67% of the whole barley.
11-14. Barley flakes are inside from pearl barley by steaming and flaking on large-
diameter smooth rolls. The flakes are dried to about 10.5% moisture content before
packing.
Pearl barley is used for soups and dressings and for the manufacture of puffed barley, a
ready-to-eat breakfast cereal. Pearl barley is also a starting material for manufacture of barley
flour. Milled barley products are also used for extruded food snacks, as croutons in soup and
salad dressings, as crunches for nut substitutes.
BARLEY FLOUR
Barley flour is milled from pearl barley, blocked barley or unpearled hull-less barley.
Optimum tempering conditions are 13% moisture content for 48 h for pearl barley, 14% moisture
content for 48 h for unpearled hull-less barley. The milling system uses roller mills with fluted
and smooth rolls, and plan sifters,
When blocked barley or whole barley is used for milling barley flour, due allowance
must be made for the greatly increased quantity of by-products, which would otherwise choke
the system. Barley flour is also a by-product of the cutting, pearling and polishing processes.
Average extraction rate of 92% of barley flour is obtained from pearl barley representing 67% of
the grain, i.e. an overall extraction rate 55% based on the original whole grain. By using blocked
barley, an overall extraction rate of 59% on the whole grain could be obtained but the product
would be considerably less pure than that milled from pearl barley.
Barley flour is used in the manufacture of flat bread, for infant foods and for food
specialties. It is also a component of composite flours used for risking yeast-raised bread.
Pre-gelatinized barley flour, which has high absorbent properties, provides a good binder and
thickener.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125052.
E-mail- [email protected]
E-mail- [email protected]
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125052.
E-mail- [email protected]
E-mail- [email protected]
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125052.
E-mail- [email protected]
E-mail- [email protected]
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125052.
E-mail- [email protected]
E-mail- [email protected]
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125052.
E-mail- [email protected]
Present Uses of Barley and Barley Products
Type Use
Feed Livestock
Poultry
Pearling Pot barley for soups and dressings
Pearled barley for soups and dressings
Flour
Feed
Milling Flour for baby foods and food specialties
Grits
Feed
Malting Brewer’s beverages
Brewer’s grains for dairy feeds
Brewer’s yeast for animal feed, human food,
and fine chemicals
Distiller’s alcohol
Distiller’s spirits
Distiller’s solubles for livestock and poultry
feeds
Distiller’s grains for livestock and poultry feeds
Specialty Malts
·High dried
·Dextrin for breakfast cereals, sugar
colorings, dark beers and coffee
substitutes
·Caramel for breakfast cereals, sugar
colorings, dark beers and coffee
substitutes
·Black for breakfast cereals, sugar
colorings, dark beers and coffee
substitutes
Export
Malt flour for wheat flour supplements, human
and animal food production
Malted milk concentrates for malted milk,
malted milk and infant food
Malted syrups for medicinal, textile, baking
uses and for breakfast cereals and candies
Malted sprouts for dairy feeds, vinegar
manufacture and industrial fermentations
E-mail- [email protected]
Present Uses of Barley and Barley Products
Type Use
Feed Livestock
Poultry
Pearling Pot barley for soups and dressings
Pearled barley for soups and dressings
Flour
Feed
Milling Flour for baby foods and food specialties
Grits
Feed
Malting Brewer’s beverages
Brewer’s grains for dairy feeds
Brewer’s yeast for animal feed, human food,
and fine chemicals
Distiller’s alcohol
Distiller’s spirits
Distiller’s solubles for livestock and poultry
feeds
Distiller’s grains for livestock and poultry feeds
Specialty Malts
·High dried
·Dextrin for breakfast cereals, sugar
colorings, dark beers and coffee
substitutes
·Caramel for breakfast cereals, sugar
colorings, dark beers and coffee
substitutes
·Black for breakfast cereals, sugar
colorings, dark beers and coffee
substitutes
Export
Malt flour for wheat flour supplements, human
and animal food production
Malted milk concentrates for malted milk,
malted milk and infant food
Malted syrups for medicinal, textile, baking
uses and for breakfast cereals and candies
Malted sprouts for dairy feeds, vinegar
manufacture and industrial fermentations
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125052.
E-mail- [email protected]
Sorghum and Millets
Introduction
Sorghum and millets have been important staples in the semi-arid tropics of Asia and Africa for
centuries. These crops are still the principal sources of energy, protein, vitamins and minerals for
millions of the poorest people in these regions.
Sorghum and millets are grown in harsh environments where other crops grow or yield poorly.
They are grown with limited water resources and usually without application of any fertilizers or
other inputs by a multitude of small-holder farmers in many countries. Therefore, and because
they are mostly consumed by disadvantaged groups, they are often referred to as "coarse grain"
or "poor people's crops". They are not usually traded in the international markets or even in local
markets in many countries. The farmers seldom, therefore, have an assured market in the event
of surplus production.
The cereals considered include sorghum, pearl millet, finger millet, foxtail millet, common
millet, little millet, barnyard millet and kodo millet (Table 1).
Sorghum
Sorghum, Sorghum bicolor (L.) Moench, is known under a variety of names: great millet and
guinea corn in West Africa, kafir corn in South Africa, dura in Sudan, mtama in eastern Africa,
jowar in India and kaoliang in China. In the United States it is usually referred to as milo or
milo-maize (Table 1). The genus Sorghum is characterized by spikelets borne in pairs
TABLE 1: Origins and common names of sorghum and millets
Crop Common names Suggested origin
E-mail- [email protected]
Sorghum and Millets
Introduction
Sorghum and millets have been important staples in the semi-arid tropics of Asia and Africa for
centuries. These crops are still the principal sources of energy, protein, vitamins and minerals for
millions of the poorest people in these regions.
Sorghum and millets are grown in harsh environments where other crops grow or yield poorly.
They are grown with limited water resources and usually without application of any fertilizers or
other inputs by a multitude of small-holder farmers in many countries. Therefore, and because
they are mostly consumed by disadvantaged groups, they are often referred to as "coarse grain"
or "poor people's crops". They are not usually traded in the international markets or even in local
markets in many countries. The farmers seldom, therefore, have an assured market in the event
of surplus production.
The cereals considered include sorghum, pearl millet, finger millet, foxtail millet, common
millet, little millet, barnyard millet and kodo millet (Table 1).
Sorghum
Sorghum, Sorghum bicolor (L.) Moench, is known under a variety of names: great millet and
guinea corn in West Africa, kafir corn in South Africa, dura in Sudan, mtama in eastern Africa,
jowar in India and kaoliang in China. In the United States it is usually referred to as milo or
milo-maize (Table 1). The genus Sorghum is characterized by spikelets borne in pairs
TABLE 1: Origins and common names of sorghum and millets
Crop Common names Suggested origin
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125052.
E-mail- [email protected]
Sorghum bicolorSorghum, great millet, guinea corn, kafir corn, aura,
mtama, jowar, cholam. kaoliang, milo, milo-maize
Northeast quadrant of Africa
(Ethiopia-Sudan border)
Pennisetum
glaucum
Pearl millet, cumbu, spiked millet, bajra, bulrush
millet, candle millet, dark millet
Tropical West Africa
Eleusine coracanaFinger millet, African millet, koracan, ragi, wimbi,
bulo, telebun
Uganda or neighbouring region
Setaria italicaFoxtail millet, Italian millet, German millet,
Hungarian millet, Siberian millet
Eastern Asia (China)
Panicum miliaceumProso millet, common millet, hog millet, broom-
corn millet, Russian millet, brown corn
Central and eastern Asia
Panicum
sumatrense
Little millet Southeast Asia
Echinochloa crus-
galli
Barnyard millet, sawa millet, Japanese barnyard
millet
Japan
Paspalum
scrobiculatum
Kodo millet India
Sorghum was probably taken to India from eastern Africa during the first millennium BC. It is
reported to have existed there around 1000 BC. Sorghum was probably taken in ships as food in
the first instance.
The spread along the coast of Southeast Asia and around China may have taken place about the
beginning of the Christian era, but it is also possible that sorghum arrived much earlier in China
via the silk trade routes.
Pearl millet
Pearl millet, Pennisetum glaucum, is also known as spiked millet, bajra (in India) and bulrush
millet. The height of the pearl millet plant may range from 0.5 to 4 m and the grain can be nearly
white, pale yellow, brown, grey, slate blue or purple. The ovoid grains are about 3 to 4 mm long,
much larger than those of other millets, and the 1000 seed weight ranges from 2.5 to 14 g with a
mean of 8 g. The size of the pearl millet kernel is about one-third that of sorghum. The relative
proportion of germ to endosperm is higher than in sorghum.
Minor millets
Minor millets (also referred to as small millets) have received far less attention than sorghum in
terms of cultivation and utilization. They include
·finger millet (Eleusine coracana),
·foxtail millet (Setaria italica),
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Sorghum bicolorSorghum, great millet, guinea corn, kafir corn, aura,
mtama, jowar, cholam. kaoliang, milo, milo-maize
Northeast quadrant of Africa
(Ethiopia-Sudan border)
Pennisetum
glaucum
Pearl millet, cumbu, spiked millet, bajra, bulrush
millet, candle millet, dark millet
Tropical West Africa
Eleusine coracanaFinger millet, African millet, koracan, ragi, wimbi,
bulo, telebun
Uganda or neighbouring region
Setaria italicaFoxtail millet, Italian millet, German millet,
Hungarian millet, Siberian millet
Eastern Asia (China)
Panicum miliaceumProso millet, common millet, hog millet, broom-
corn millet, Russian millet, brown corn
Central and eastern Asia
Panicum
sumatrense
Little millet Southeast Asia
Echinochloa crus-
galli
Barnyard millet, sawa millet, Japanese barnyard
millet
Japan
Paspalum
scrobiculatum
Kodo millet India
Sorghum was probably taken to India from eastern Africa during the first millennium BC. It is
reported to have existed there around 1000 BC. Sorghum was probably taken in ships as food in
the first instance.
The spread along the coast of Southeast Asia and around China may have taken place about the
beginning of the Christian era, but it is also possible that sorghum arrived much earlier in China
via the silk trade routes.
Pearl millet
Pearl millet, Pennisetum glaucum, is also known as spiked millet, bajra (in India) and bulrush
millet. The height of the pearl millet plant may range from 0.5 to 4 m and the grain can be nearly
white, pale yellow, brown, grey, slate blue or purple. The ovoid grains are about 3 to 4 mm long,
much larger than those of other millets, and the 1000 seed weight ranges from 2.5 to 14 g with a
mean of 8 g. The size of the pearl millet kernel is about one-third that of sorghum. The relative
proportion of germ to endosperm is higher than in sorghum.
Minor millets
Minor millets (also referred to as small millets) have received far less attention than sorghum in
terms of cultivation and utilization. They include
·finger millet (Eleusine coracana),
·foxtail millet (Setaria italica),
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125052.
E-mail- [email protected]
·kodo millet (Paspalum scrobiculatum),
·common or prove millet (Panicum miliaceum),
·little millet (Panicum sumatrense) and
·barnyard or sawa millet (Echinochloa crusgalli and Echinochloa corona).
Finger millet
Finger millet, Eleusine coracana L., is also known as African millet, koracan, ragi (India),
wimbi (Swahili), bulo (Uganda) and telebun (the Sudan). It is an important staple food in parts of
eastern and central Africa and India.
Foxtail millet
Foxtail millet, Setaria italica L., is also known as Italian, German Hungarian or Siberian millet.
Common millet
Common millet, Panicum miliaceum L., is also known as prove millet, hog millet, broom-corn
millet, Russian millet and brown corn.
Little millet
Little millet, Panicum sumatrense, is grown throughout India to a limited extent up to altitudes
of 2 100 m but is of little importance elsewhere.
Barnyard millet
Barnyard, Japanese barnyard or sawa millet Echinochloa crusgalli (L.) P.B. and Echinochloa
colona (L.) Link] is the fastest growing of all millets and produces a crop in six weeks. It is
grown in India, Japan and China as a substitute for rice when the paddy fails.
Kodo millet
Kodo millet, Paspalum scrobiculatum L., is a minor grain crop in India but is of great
importance in the Deccan Plateau. Its cultivation in India is generally confined to Gujarat,
Karnataka and parts of Tamil Nadu. Some forms have been reported to be poisonous to humans
and animals, possibly because of a fungus infecting the grain.
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·kodo millet (Paspalum scrobiculatum),
·common or prove millet (Panicum miliaceum),
·little millet (Panicum sumatrense) and
·barnyard or sawa millet (Echinochloa crusgalli and Echinochloa corona).
Finger millet
Finger millet, Eleusine coracana L., is also known as African millet, koracan, ragi (India),
wimbi (Swahili), bulo (Uganda) and telebun (the Sudan). It is an important staple food in parts of
eastern and central Africa and India.
Foxtail millet
Foxtail millet, Setaria italica L., is also known as Italian, German Hungarian or Siberian millet.
Common millet
Common millet, Panicum miliaceum L., is also known as prove millet, hog millet, broom-corn
millet, Russian millet and brown corn.
Little millet
Little millet, Panicum sumatrense, is grown throughout India to a limited extent up to altitudes
of 2 100 m but is of little importance elsewhere.
Barnyard millet
Barnyard, Japanese barnyard or sawa millet Echinochloa crusgalli (L.) P.B. and Echinochloa
colona (L.) Link] is the fastest growing of all millets and produces a crop in six weeks. It is
grown in India, Japan and China as a substitute for rice when the paddy fails.
Kodo millet
Kodo millet, Paspalum scrobiculatum L., is a minor grain crop in India but is of great
importance in the Deccan Plateau. Its cultivation in India is generally confined to Gujarat,
Karnataka and parts of Tamil Nadu. Some forms have been reported to be poisonous to humans
and animals, possibly because of a fungus infecting the grain.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125052.
E-mail- [email protected]
Grains and their structure
Kernels of sorghum and millets show considerable diversity in colour, shape, size and certain
anatomical components (Table 2).
The basic kernel structure is similar in sorghum and different millets. The principal anatomical
components are pericarp, germ or embryo and endosperm. In finger, prove and foxtail millets the
pericarp is like a sack, loosely attached to the endosperm at only one point. In these utricle-type
kernels the pericarp easily breaks away, leaving the seed-coat or testa to protect the inner
endosperm. The kernels of sorghum and pearl millet are of the caryopsis type, in which the
pericarp is completely fused to the endosperm.
The relative distribution of the three main kernel components varies. In the sorghum kernel the
distribution by weight is
·Pericarp 6 percent,
·Endosperm 84 percent and
·Germ 10 percent.
In pearl millet, it is
·Pericarp 8.4 percent,
·Endosperm 75 percent and
·Germ 16.5 percent.
Pericarp
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Grains and their structure
Kernels of sorghum and millets show considerable diversity in colour, shape, size and certain
anatomical components (Table 2).
The basic kernel structure is similar in sorghum and different millets. The principal anatomical
components are pericarp, germ or embryo and endosperm. In finger, prove and foxtail millets the
pericarp is like a sack, loosely attached to the endosperm at only one point. In these utricle-type
kernels the pericarp easily breaks away, leaving the seed-coat or testa to protect the inner
endosperm. The kernels of sorghum and pearl millet are of the caryopsis type, in which the
pericarp is completely fused to the endosperm.
The relative distribution of the three main kernel components varies. In the sorghum kernel the
distribution by weight is
·Pericarp 6 percent,
·Endosperm 84 percent and
·Germ 10 percent.
In pearl millet, it is
·Pericarp 8.4 percent,
·Endosperm 75 percent and
·Germ 16.5 percent.
Pericarp
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125052.
E-mail- [email protected]
Pericarp is the outermost structural component of the caryopsis and is composed of three
sublayers, namely epicarp, mesocarp and endocarp. The epicarp is further divided into
epidermis and hypodermic. In the sorghum caryopsis, the epidermis is composed of thick,
elongated, rectangular cells that have a coating of cutin on the outer surface. Often pigment is
present in the epidermis. The hypodermis is composed of slightly smaller cells than the
epidermis and is one to three cell layers in thickness. The mesocarp, the middle part, is the
thickest layer of the sorghum pericarp. Mould resistance in sorghum is associated with thin
mesocarp. Grains with thick mesocarp on a hard endosperm are preferred for dehulling by hand
pounding. The endocarp, the innermost sublayer of the pericarp, consists of cross cells and a
layer of tube cells which transport moisture into the kernel. During dry milling of sorghum, the
breakage occurs at the cross and tube cell layers.
GrainType Shape Colour 1 000-kenel
weight
(g)
SorghumCaryopsis Spherical White, yellow, red,
brown
25-30
Pearl
millet
Caryopsis Ovoid,
hexagonal,
globose
Grey, white, yellow,
brown, purple
2.5-14
Finger
millet
Utricle Globose Yellow, white, red,
brown, violet
2.6
Proso
millet
Utricle 4.7-7.2
Foxtail
millet
Utricle 1.86
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Pericarp is the outermost structural component of the caryopsis and is composed of three
sublayers, namely epicarp, mesocarp and endocarp. The epicarp is further divided into
epidermis and hypodermic. In the sorghum caryopsis, the epidermis is composed of thick,
elongated, rectangular cells that have a coating of cutin on the outer surface. Often pigment is
present in the epidermis. The hypodermis is composed of slightly smaller cells than the
epidermis and is one to three cell layers in thickness. The mesocarp, the middle part, is the
thickest layer of the sorghum pericarp. Mould resistance in sorghum is associated with thin
mesocarp. Grains with thick mesocarp on a hard endosperm are preferred for dehulling by hand
pounding. The endocarp, the innermost sublayer of the pericarp, consists of cross cells and a
layer of tube cells which transport moisture into the kernel. During dry milling of sorghum, the
breakage occurs at the cross and tube cell layers.
GrainType Shape Colour 1 000-kenel
weight
(g)
SorghumCaryopsis Spherical White, yellow, red,
brown
25-30
Pearl
millet
Caryopsis Ovoid,
hexagonal,
globose
Grey, white, yellow,
brown, purple
2.5-14
Finger
millet
Utricle Globose Yellow, white, red,
brown, violet
2.6
Proso
millet
Utricle 4.7-7.2
Foxtail
millet
Utricle 1.86
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125052.
E-mail- [email protected]
TABLE 2: Structural features of kernels of sorghum and some millets
Seed - coat Alcurone
Grain Number of
layers
PigmentedThickness (pm)Number of layersCell size (pm)
Sorghum 1 Sometimes0.4 1
Pearl millet 1 Sometimes0.4 1 16-30 x 5-15
Finger millet 5 Yes 10.8-24.2 1 18 x 7.6
Proso millet 1 No 0.2-0.4 1 12 x 6
Foxtail millet 1 1
Starch granules Protein bodies
Grain Diameter
(µm)
Peripheral
zone (µm)
Corneous
zone (µm)
Floury zone (µm)Type Size (µm)Location
Sorghum 20-30 Simple 0.3-3 All areas
Pearl millet10-12 6.4 6.4 7.6 Simple 0.6-0.7 All areas
Finger millet3-21 8-16.5 3-19 11-21 Simple/
compound
2.0 Peripheral/
corneous
Proso millet2-10 3.9 4.1 4.1 Simple 0.5-1.7 Peripheral
Foxtail millet10
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TABLE 2: Structural features of kernels of sorghum and some millets
Seed - coat Alcurone
Grain Number of
layers
PigmentedThickness (pm)Number of layersCell size (pm)
Sorghum 1 Sometimes0.4 1
Pearl millet 1 Sometimes0.4 1 16-30 x 5-15
Finger millet 5 Yes 10.8-24.2 1 18 x 7.6
Proso millet 1 No 0.2-0.4 1 12 x 6
Foxtail millet 1 1
Starch granules Protein bodies
Grain Diameter
(µm)
Peripheral
zone (µm)
Corneous
zone (µm)
Floury zone (µm)Type Size (µm)Location
Sorghum 20-30 Simple 0.3-3 All areas
Pearl millet10-12 6.4 6.4 7.6 Simple 0.6-0.7 All areas
Finger millet3-21 8-16.5 3-19 11-21 Simple/
compound
2.0 Peripheral/
corneous
Proso millet2-10 3.9 4.1 4.1 Simple 0.5-1.7 Peripheral
Foxtail millet10
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125052.
E-mail- [email protected]
E-mail- [email protected]
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125052.
E-mail- [email protected]
The pericarp of the pearl millet caryopsis consists of an epicarp with one or two cell layers, a mesocarp
that varies in thickness because of genetic factors and an endocarp made up of cross and tube cells. The
mesocarp layer of pearl millet does not contain starch granules; these are found only in sorghum
mesocarp. During decortication or milling, the pericarp of pearl millet breaks at the cross and tube cell
layers and fragments of endocarp may remain with the endosperm.
Seed-coat or testa
Just underneath the endocarp is the testa layer or seed-coat. In some sorghum genotypes the testa is highly
pigmented. The presence of pigment and the colour are a genetic character. The thickness of the testa layer
is not uniform
Endosperm
The largest component of the cereal kernel is the endosperm, which is a major storage tissue. It is
composed of an aleurone layer and peripheral corneous and floury zones. In all the millets and sorghum,
the aleurone layer is a single layer of cells, which lies just below the seed-coat or testa. The aleurone cells
are rich in minerals, B-complex vitamins and oil and contain some hydrolysing enzymes.
The peripheral endosperm is distinguished by long rectangular cells, which are densely packed and
contain starch granules and protein bodies enmeshed in the protein matrix.
The protein bodies in the endosperm of sorghum and millets are spherical and differ in size among species
and within the endosperm of a single kernel. In sorghum, the number of protein bodies decreases as the
starch content increases.
Grain texture is one of the most important determinants of the processing and food quality of sorghum and
millets. Hard endosperm sorghum when decorticated gives fewer brokers and more full grains than softer-
endosperm sorghum. In dry milling, the flour yield is higher in corneous than in soft floury types. On the
other hand, in wet milling the starch yield is higher in soft-endosperm genotypes. In the preparation of
thick porridge, varieties with a higher proportion of vitreous endosperm are preferred. Such varieties are
also suitable for popping. For preparation of bread, fermented or unfermented, the flour of soft-endosperm
sorghum is highly preferred.
Germ
The embryonic axis and the scutellum are the two major parts of the germ. The scutellum is a storage
tissue rich in lipids, protein, enzymes and minerals. The oil in the sorghum germ is rich in polyunsaturated
fatty acids and is similar to corn oil.
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The pericarp of the pearl millet caryopsis consists of an epicarp with one or two cell layers, a mesocarp
that varies in thickness because of genetic factors and an endocarp made up of cross and tube cells. The
mesocarp layer of pearl millet does not contain starch granules; these are found only in sorghum
mesocarp. During decortication or milling, the pericarp of pearl millet breaks at the cross and tube cell
layers and fragments of endocarp may remain with the endosperm.
Seed-coat or testa
Just underneath the endocarp is the testa layer or seed-coat. In some sorghum genotypes the testa is highly
pigmented. The presence of pigment and the colour are a genetic character. The thickness of the testa layer
is not uniform
Endosperm
The largest component of the cereal kernel is the endosperm, which is a major storage tissue. It is
composed of an aleurone layer and peripheral corneous and floury zones. In all the millets and sorghum,
the aleurone layer is a single layer of cells, which lies just below the seed-coat or testa. The aleurone cells
are rich in minerals, B-complex vitamins and oil and contain some hydrolysing enzymes.
The peripheral endosperm is distinguished by long rectangular cells, which are densely packed and
contain starch granules and protein bodies enmeshed in the protein matrix.
The protein bodies in the endosperm of sorghum and millets are spherical and differ in size among species
and within the endosperm of a single kernel. In sorghum, the number of protein bodies decreases as the
starch content increases.
Grain texture is one of the most important determinants of the processing and food quality of sorghum and
millets. Hard endosperm sorghum when decorticated gives fewer brokers and more full grains than softer-
endosperm sorghum. In dry milling, the flour yield is higher in corneous than in soft floury types. On the
other hand, in wet milling the starch yield is higher in soft-endosperm genotypes. In the preparation of
thick porridge, varieties with a higher proportion of vitreous endosperm are preferred. Such varieties are
also suitable for popping. For preparation of bread, fermented or unfermented, the flour of soft-endosperm
sorghum is highly preferred.
Germ
The embryonic axis and the scutellum are the two major parts of the germ. The scutellum is a storage
tissue rich in lipids, protein, enzymes and minerals. The oil in the sorghum germ is rich in polyunsaturated
fatty acids and is similar to corn oil.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125052.
E-mail- [email protected]
Production and utilization
Sorghum production
The total production of sorghum in the world in 1990 was 58 million tonnes, a decrease from 60 million
tonnes in the year 1989 and 62 million tonnes in 1988 (FAO, 1991).
The five largest producers of sorghum in the world (Table 4) are the United States (25 percent), India (21 .
5 percent), Mexico (almost 11 percent), China (9 percent) and Nigeria (almost 7 percent). Together these
five countries account for 73 percent of total world production.
TABLE 3: Area, yield and production of sorghum by region, 1990
Source: FAO, 1991.
TABLE 4: Leading sorghum producers, 1990
Country
Area Production
(10³ ha) (% total) (10³ ha) (% total)
United
States
3 674 8.3 14 516 25.0
India 15300 34.5 12500 21.5
Mexico1 830 4.1 6 230 10.7
China 1900 4.3 5310 91
Nigeria6 000 13.5 4 000 6.9
Region
Area
Yield (kg/ha)
Production
(10³ ha) (% total) (10³ ha) (% total)
North and Central
America
5 970 13.5 3 572 21 325 36.7
Asia 18451 41.6 1 023 18 867 32.4
Africa 17 799 40.1 718 12 784 22.0
South America 1353 3.1 2 614 3 537 6.1
Oceania 407 0.9 2 298 934 1.6
World (1990) 44 352 1 312 58190
World (1989) 44 695 1 340 59 991
E-mail- [email protected]
Production and utilization
Sorghum production
The total production of sorghum in the world in 1990 was 58 million tonnes, a decrease from 60 million
tonnes in the year 1989 and 62 million tonnes in 1988 (FAO, 1991).
The five largest producers of sorghum in the world (Table 4) are the United States (25 percent), India (21 .
5 percent), Mexico (almost 11 percent), China (9 percent) and Nigeria (almost 7 percent). Together these
five countries account for 73 percent of total world production.
TABLE 3: Area, yield and production of sorghum by region, 1990
Source: FAO, 1991.
TABLE 4: Leading sorghum producers, 1990
Country
Area Production
(10³ ha) (% total) (10³ ha) (% total)
United
States
3 674 8.3 14 516 25.0
India 15300 34.5 12500 21.5
Mexico1 830 4.1 6 230 10.7
China 1900 4.3 5310 91
Nigeria6 000 13.5 4 000 6.9
Region
Area
Yield (kg/ha)
Production
(10³ ha) (% total) (10³ ha) (% total)
North and Central
America
5 970 13.5 3 572 21 325 36.7
Asia 18451 41.6 1 023 18 867 32.4
Africa 17 799 40.1 718 12 784 22.0
South America 1353 3.1 2 614 3 537 6.1
Oceania 407 0.9 2 298 934 1.6
World (1990) 44 352 1 312 58190
World (1989) 44 695 1 340 59 991
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125052.
E-mail- [email protected]
Source: FAO, 1991.
Sorghum utilization
Total consumption of sorghum closely follows the global pattern of output, since most of it is consumed in
the countries where it is grown. Sorghum is used for two distinct purposes: human food and animal feed.
Although in the early 1960s a very large part of the sorghum output was used directly as human food, its
share has continuously declined since then. In fact, consumption of sorghum as animal feed has more than
doubled, from 30 to 60 percent, since the early 1960s, while the volume of total food use has remained
unchanged or has slightly declined (Table 6). In North and Central America, South America and Oceania
most of the sorghum produced is used for animal feed.
TABLE 6: Sorghum utilization, 1981-85 average and growth from 1961-65 to 1981 - 85
Region
1981-85 average (million tonnes)Annual growth from 1961-65 to 1981
(%)
FoodFeedOther uses Total Food FeedOther uses Total
Africa 8.00.42.3 10.7 1.5 3.5-0.6 1.0
Asia 15.16.32.1 23.5 - 7.80.2 1.2
Central
America
0.38.40.2 8.9 2.0 13.2- 12.1
South
America
- 4.60.3 4.9 - 8.55.7 8.3
North
America
- 12.60.1 12.7 - 0.5- 0.5
Europe - 1.4- 1.4 - -2.5- -2.5
USSR - 2.30.3 2.6 - 17.0- 17.0
Oceania - 0.4- 0.4 - 3.5 3.5
World 23.436.45 3 65.1 0.5 3.80.4 2.1
Developing
countries
23.215.64.8 43.6 0.5 10.30.1 1.7
Developed
countries
0.220.80.5 21.5 3.5 1.74.7 2.2
Source: FAO, 1988.
Human food
E-mail- [email protected]
Source: FAO, 1991.
Sorghum utilization
Total consumption of sorghum closely follows the global pattern of output, since most of it is consumed in
the countries where it is grown. Sorghum is used for two distinct purposes: human food and animal feed.
Although in the early 1960s a very large part of the sorghum output was used directly as human food, its
share has continuously declined since then. In fact, consumption of sorghum as animal feed has more than
doubled, from 30 to 60 percent, since the early 1960s, while the volume of total food use has remained
unchanged or has slightly declined (Table 6). In North and Central America, South America and Oceania
most of the sorghum produced is used for animal feed.
TABLE 6: Sorghum utilization, 1981-85 average and growth from 1961-65 to 1981 - 85
Region
1981-85 average (million tonnes)Annual growth from 1961-65 to 1981
(%)
FoodFeedOther uses Total Food FeedOther uses Total
Africa 8.00.42.3 10.7 1.5 3.5-0.6 1.0
Asia 15.16.32.1 23.5 - 7.80.2 1.2
Central
America
0.38.40.2 8.9 2.0 13.2- 12.1
South
America
- 4.60.3 4.9 - 8.55.7 8.3
North
America
- 12.60.1 12.7 - 0.5- 0.5
Europe - 1.4- 1.4 - -2.5- -2.5
USSR - 2.30.3 2.6 - 17.0- 17.0
Oceania - 0.4- 0.4 - 3.5 3.5
World 23.436.45 3 65.1 0.5 3.80.4 2.1
Developing
countries
23.215.64.8 43.6 0.5 10.30.1 1.7
Developed
countries
0.220.80.5 21.5 3.5 1.74.7 2.2
Source: FAO, 1988.
Human food
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125052.
E-mail- [email protected]
While total food consumption of all cereals has risen considerably during the past 35 years, world food
consumption of sorghum has remained stagnant, mainly because, although nutritionally sorghum
compares well with other grains, it is regarded in many countries as an inferior grain. More than 95
percent of total food use of sorghum occurs in countries of Africa and Asia (Table 6
Animal feed
Grain use for animal feed has been a dynamic element in the stimulation of global sorghum consumption.
The demand for sorghum for feed purposes has been the main driving force in raising global production
and international trade since the early 1960s. The demand is heavily concentrated in the developed
countries, where animal feed accounts for about 97 percent of total use.
Millet production
Pearl millet, finger millet and prove millet account for a large proportion of the world production. Asia,
Africa and the former Soviet Union produce almost all the world's millets, as shown in Table 7. The major
producers of millets in 1990 were India (39 percent), China (15 percent), Nigeria (13 percent) and the
Soviet Union (12 percent) (Table 8).
TABLE 7: Area, yield and production of millet, by region, 1990
Region
Area
Yield (kg/ha)
Production
(10³ ha) (% of total) (10³ t)(% of total)
Asia 20 853 55.5 804 16 767 56.2
Africa 13 548 36.1 669 9 066 30.4
USSR 2903 7.7 1 256 3647 12.2
North and Central
America
150 0.4 1 200 180 0.6
South America55 0.2 1 655 91 0.3
Oceania 34 0.1 882 30 0.1
World 37565 100 794 29817 100
Source: FAO,1991.
TABLE 8: Leading millet producers, 1990
Country
Area Production
(10³ ha) (% of total)(10³ t) (% of total)
E-mail- [email protected]
While total food consumption of all cereals has risen considerably during the past 35 years, world food
consumption of sorghum has remained stagnant, mainly because, although nutritionally sorghum
compares well with other grains, it is regarded in many countries as an inferior grain. More than 95
percent of total food use of sorghum occurs in countries of Africa and Asia (Table 6
Animal feed
Grain use for animal feed has been a dynamic element in the stimulation of global sorghum consumption.
The demand for sorghum for feed purposes has been the main driving force in raising global production
and international trade since the early 1960s. The demand is heavily concentrated in the developed
countries, where animal feed accounts for about 97 percent of total use.
Millet production
Pearl millet, finger millet and prove millet account for a large proportion of the world production. Asia,
Africa and the former Soviet Union produce almost all the world's millets, as shown in Table 7. The major
producers of millets in 1990 were India (39 percent), China (15 percent), Nigeria (13 percent) and the
Soviet Union (12 percent) (Table 8).
TABLE 7: Area, yield and production of millet, by region, 1990
Region
Area
Yield (kg/ha)
Production
(10³ ha) (% of total) (10³ t)(% of total)
Asia 20 853 55.5 804 16 767 56.2
Africa 13 548 36.1 669 9 066 30.4
USSR 2903 7.7 1 256 3647 12.2
North and Central
America
150 0.4 1 200 180 0.6
South America55 0.2 1 655 91 0.3
Oceania 34 0.1 882 30 0.1
World 37565 100 794 29817 100
Source: FAO,1991.
TABLE 8: Leading millet producers, 1990
Country
Area Production
(10³ ha) (% of total)(10³ t) (% of total)
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125052.
E-mail- [email protected]
India 17 000 45.3 11 500 38.6
China 2 601 6.9 4 401 14.8
Nigeria 4 000 10.7 4 000 13.4
USSR 2 903 7.7 3 647 12.2
Niger 3 100 8.3 1 133 3.8
Mali 900 2.4 695 2.3
Uganda 400 1.1 620 2.1
Burkina Faso1 150 3.1 597 2.0
Senegal 865 2.3 514 1.7
Nepal 200 0.5 240 0.8
Total 33 119 88.2 27 347 91.7
World(1990)37 565 29 817
World
(1989)
37 409 29 962
Source: FAO. 1991.
TABLE 9: Sources of energy and protein in the food supply of the world's ten leading millet
producers, 1987-89
Country
Energy per caput per day (kcal)Protein per caput per day (g)
TotalVegetable
products
Percentage
of total
Animal
products
TotalVegetable
products
Percentage
of total
Animal
products
India21962 048 93.3 148 53.245.6 85.7 7.6
China26342 365 89.8 269 62.850.7 80.7 12.1
Nigeria23062 248 97.5 58 49.543.6 88.1 5.9
USSR 33802 444 72.3 936 106.250.1 47.2 56.1
Niger22972 152 93.7 145 64.053.2 83.1 10.8
Mali 22342 090 93.6 144 62.550.1 80.2 12.4
Uganda21362 010 94.1 126 48.138.7 80.5 9.4
Burkina
Faso
22862 186 95.6 100 69.862.6 89.7 7.2
Senegal23742 160 91.0 214 68.249.9 73.0 18.3
Nepal20741 937 93.4 137 52.544.8 85.3 7.7
E-mail- [email protected]
India 17 000 45.3 11 500 38.6
China 2 601 6.9 4 401 14.8
Nigeria 4 000 10.7 4 000 13.4
USSR 2 903 7.7 3 647 12.2
Niger 3 100 8.3 1 133 3.8
Mali 900 2.4 695 2.3
Uganda 400 1.1 620 2.1
Burkina Faso1 150 3.1 597 2.0
Senegal 865 2.3 514 1.7
Nepal 200 0.5 240 0.8
Total 33 119 88.2 27 347 91.7
World(1990)37 565 29 817
World
(1989)
37 409 29 962
Source: FAO. 1991.
TABLE 9: Sources of energy and protein in the food supply of the world's ten leading millet
producers, 1987-89
Country
Energy per caput per day (kcal)Protein per caput per day (g)
TotalVegetable
products
Percentage
of total
Animal
products
TotalVegetable
products
Percentage
of total
Animal
products
India21962 048 93.3 148 53.245.6 85.7 7.6
China26342 365 89.8 269 62.850.7 80.7 12.1
Nigeria23062 248 97.5 58 49.543.6 88.1 5.9
USSR 33802 444 72.3 936 106.250.1 47.2 56.1
Niger22972 152 93.7 145 64.053.2 83.1 10.8
Mali 22342 090 93.6 144 62.550.1 80.2 12.4
Uganda21362 010 94.1 126 48.138.7 80.5 9.4
Burkina
Faso
22862 186 95.6 100 69.862.6 89.7 7.2
Senegal23742 160 91.0 214 68.249.9 73.0 18.3
Nepal20741 937 93.4 137 52.544.8 85.3 7.7
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125052.
E-mail- [email protected]
Source: FAO,1991.
Millet utilization
Of the 30 million tonnes of millet produced in the world about 90 percent is utilized in developing
countries and only a tiny volume is used in the developed countries outside the former Soviet Union.
TABLE 10: Estimated millet utilization, 1981/82 to 1985/86 average
Region or countryFood (10³
t)
Feed (10³
t)
Other uses
a
(10³ t)
Total (10³ t)Per caput
food use
(kg/yr)
Africa
b
7 094 122 1 921 9 137 13.5
Nigeria 2 365 86 700 3 151 26.5
Asia 14441 1 665 1 305 17411 5.3
China 4 857 1 120 480 6 457 4.7
India 8794 150 710 9664 11.9
USSR 800 1 107 400 2 307 2.9
World 22 3353 144 3 642 29 121 4.8
Developing countries21 5351 878 3 231 26 644 6.1
Developed countries800 1 266 411 2 477 0.7
a Food seed, manufacturing purposes and waste.
b Including fonio, and teff.
Source: FAO,1990b.
Human food
Per caput food consumption of millet varies greatly among countries, though it is highest in Africa. In
developing countries outside Africa, millet has local significance as a food in parts of some countries such
as China, India, Myanmar and the Democratic People's Republic of Korea. Although national per caput
levels are rather low in the countries that consume the most millet, i.e. China and India, food use of millet
is important in certain areas of these countries.
Animal feed
Utilization of millet as animal feed is negligible in absolute terms and compared with other uses and other
cereals. It has been estimated that only about 10 percent of the millet used globally is fed to animals.
E-mail- [email protected]
Source: FAO,1991.
Millet utilization
Of the 30 million tonnes of millet produced in the world about 90 percent is utilized in developing
countries and only a tiny volume is used in the developed countries outside the former Soviet Union.
TABLE 10: Estimated millet utilization, 1981/82 to 1985/86 average
Region or countryFood (10³
t)
Feed (10³
t)
Other uses
a
(10³ t)
Total (10³ t)Per caput
food use
(kg/yr)
Africa
b
7 094 122 1 921 9 137 13.5
Nigeria 2 365 86 700 3 151 26.5
Asia 14441 1 665 1 305 17411 5.3
China 4 857 1 120 480 6 457 4.7
India 8794 150 710 9664 11.9
USSR 800 1 107 400 2 307 2.9
World 22 3353 144 3 642 29 121 4.8
Developing countries21 5351 878 3 231 26 644 6.1
Developed countries800 1 266 411 2 477 0.7
a Food seed, manufacturing purposes and waste.
b Including fonio, and teff.
Source: FAO,1990b.
Human food
Per caput food consumption of millet varies greatly among countries, though it is highest in Africa. In
developing countries outside Africa, millet has local significance as a food in parts of some countries such
as China, India, Myanmar and the Democratic People's Republic of Korea. Although national per caput
levels are rather low in the countries that consume the most millet, i.e. China and India, food use of millet
is important in certain areas of these countries.
Animal feed
Utilization of millet as animal feed is negligible in absolute terms and compared with other uses and other
cereals. It has been estimated that only about 10 percent of the millet used globally is fed to animals.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125052.
E-mail- [email protected]
Storage and processing
When sorghum or millet is stored in developing countries, it is usually stored in small quantities in
traditional containers, often on the farm. Large quantities are seldom accumulated and bulk storage is
uncommon.
Processing involves the partial separation and/or modification of the three major constituents of the cereal
grain –
·the germ,
·the starch-containing endosperm and the
·protective pericarp.
In general, industrial methods of processing sorghum and millets are not as well developed as the methods
used for processing wheat and rice, which in most places are held in much higher regard than sorghum and
millets.
It is in processing that brown sorghums present the most difficulty, for the following reasons.
·When the pericarp is progressively removed from the outside, the testa is almost the last layer to be
removed.
·When a brown sorghum has recently been wetted, the pericarp tends to separate just above the
testa. If the pericarp is then rubbed off, the damp testa is still firmly attached to the endosperm.
·Brown sorghums are often quite soft and the endosperm tends to break apart if the seed is
subjected to mechanical impact.
The best way of separating the testa of a brown sorghum from the endosperm is to cut the endosperm from
the inside of the pericarp, as happens in roller milling. However, this is not possible using traditional
methods. It is for these reasons that brown sorghums are usually only used in the production of beer,
where some bitterness and some colour are not only acceptable but often preferred.
Traditional processing methods
Processing untreated grains
Flour made by grinding whole grain is occasionally used, particularly with the smaller millets, but in most
places where sorghum and millets are consumed the grain is partially separated into its constituents before
food is prepared from it.
The first objective of processing is usually to remove some of the hull or bran - the fibrous outer layers of
the grain. This is usually done by pounding followed by winnowing or sieving. The grain may first be
moistened with about 10 percent water or soaked overnight. When hard grains are pounded, the
endosperm remains relatively intact and can be separated from the heavy grits by winnowing. With soft
grains, the endosperm breaks into small particles and the pericarp can be separated by winnowing and
screening.
E-mail- [email protected]
Storage and processing
When sorghum or millet is stored in developing countries, it is usually stored in small quantities in
traditional containers, often on the farm. Large quantities are seldom accumulated and bulk storage is
uncommon.
Processing involves the partial separation and/or modification of the three major constituents of the cereal
grain –
·the germ,
·the starch-containing endosperm and the
·protective pericarp.
In general, industrial methods of processing sorghum and millets are not as well developed as the methods
used for processing wheat and rice, which in most places are held in much higher regard than sorghum and
millets.
It is in processing that brown sorghums present the most difficulty, for the following reasons.
·When the pericarp is progressively removed from the outside, the testa is almost the last layer to be
removed.
·When a brown sorghum has recently been wetted, the pericarp tends to separate just above the
testa. If the pericarp is then rubbed off, the damp testa is still firmly attached to the endosperm.
·Brown sorghums are often quite soft and the endosperm tends to break apart if the seed is
subjected to mechanical impact.
The best way of separating the testa of a brown sorghum from the endosperm is to cut the endosperm from
the inside of the pericarp, as happens in roller milling. However, this is not possible using traditional
methods. It is for these reasons that brown sorghums are usually only used in the production of beer,
where some bitterness and some colour are not only acceptable but often preferred.
Traditional processing methods
Processing untreated grains
Flour made by grinding whole grain is occasionally used, particularly with the smaller millets, but in most
places where sorghum and millets are consumed the grain is partially separated into its constituents before
food is prepared from it.
The first objective of processing is usually to remove some of the hull or bran - the fibrous outer layers of
the grain. This is usually done by pounding followed by winnowing or sieving. The grain may first be
moistened with about 10 percent water or soaked overnight. When hard grains are pounded, the
endosperm remains relatively intact and can be separated from the heavy grits by winnowing. With soft
grains, the endosperm breaks into small particles and the pericarp can be separated by winnowing and
screening.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125052.
E-mail- [email protected]
When suitably prepared grain is pounded, the bran fraction contains most of the pericarp, along with some
germ and endosperm. This fraction is usually fed to domestic animals. The other fraction, containing most
of the endosperm and much of the germ along with some pericarp, is retained for human consumption.
Retaining the germ in the flour will improve aspects of its nutritional quality, but at the same time it will
increase the rate at which the flour will become rancid. This is particularly important in the case of pearl
millet.
Dry, moistened or wet grain is normally pounded with a wooden pestle in a wooden or stone mortar.
Moistening the grain by adding about 10 percent water facilitates not only the removal of the fibrous bran,
but also separation of the germ and the endosperm, if desired. Although this practice produces a slightly
moist flour, many people temper the grain in this way before they pound it. Pounding moist or dry grain
by hand is very laborious, time consuming and inefficient. Pounding gives a non-uniform product that has
poor keeping qualities.
The particle size of the endosperm fraction can be reduced by crushing or grinding to produce coarse grits
or fine flour. Traditional grinding stones used to grind whole or decorticated grain to flour usually consist
of a small stone which is held in the hand and a larger flat stone which is placed on the ground. Grain,
which should be fairly dry, is crushed and pulverized by the backward and forward movement of the
hand-held stone on the lower stone.
In wet milling, the sorghum or millet is soaked in water overnight (and sometimes longer) and then
ground to a batter by hand, often between two stones. Soaking makes the endosperm very soft and the
pericarp quite tough and makes grinding much easier, but it gives a batter or paste instead of flour.
Processing malted grains
Malting involves germinating grain and allowing it to sprout. Typically the grain is soaked for 16 to 24
hours, which allows it to absorb sufficient moisture for germination and for sprouts to appear. However,
germinated sorghum rootless and sprouts contain very large amounts of dhurrin, a cyanogenic glucoside,
which on hydrolysis produces a potent toxin variously known as prussic acid, hydrocyanic acid (HCN)
and cyanide. The fresh shoots and rootless of germinated sorghum and their extracts must therefore never
be consumed, either by people or by animals, except in very small quantities (e.g. when the germinated
grain is used just as a source of enzymes).
Malted sorghum has traditionally been used in several countries in Africa, but always after careful
removal of the toxic parts.
In the germination process, the grain produces a-amylase, an enzyme that converts insoluble starch to
soluble sugars. This has the effect of thinning paste made by heating a slurry of starch in water, in turn
allowing a higher caloric density in paste of a given viscosity, since as much as three times more flour can
be used when the grain has been germinated.
In India, malted finger millet is common and is considered to be superior to malted sorghum and malted
maize. Studies have shown that finger millet develops higher amylase activity than sorghum and other
millets. Germination of grain is reported to change the amino acid composition, convert starch into sugars
and improve the availability of fat, vitamins and minerals.
E-mail- [email protected]
When suitably prepared grain is pounded, the bran fraction contains most of the pericarp, along with some
germ and endosperm. This fraction is usually fed to domestic animals. The other fraction, containing most
of the endosperm and much of the germ along with some pericarp, is retained for human consumption.
Retaining the germ in the flour will improve aspects of its nutritional quality, but at the same time it will
increase the rate at which the flour will become rancid. This is particularly important in the case of pearl
millet.
Dry, moistened or wet grain is normally pounded with a wooden pestle in a wooden or stone mortar.
Moistening the grain by adding about 10 percent water facilitates not only the removal of the fibrous bran,
but also separation of the germ and the endosperm, if desired. Although this practice produces a slightly
moist flour, many people temper the grain in this way before they pound it. Pounding moist or dry grain
by hand is very laborious, time consuming and inefficient. Pounding gives a non-uniform product that has
poor keeping qualities.
The particle size of the endosperm fraction can be reduced by crushing or grinding to produce coarse grits
or fine flour. Traditional grinding stones used to grind whole or decorticated grain to flour usually consist
of a small stone which is held in the hand and a larger flat stone which is placed on the ground. Grain,
which should be fairly dry, is crushed and pulverized by the backward and forward movement of the
hand-held stone on the lower stone.
In wet milling, the sorghum or millet is soaked in water overnight (and sometimes longer) and then
ground to a batter by hand, often between two stones. Soaking makes the endosperm very soft and the
pericarp quite tough and makes grinding much easier, but it gives a batter or paste instead of flour.
Processing malted grains
Malting involves germinating grain and allowing it to sprout. Typically the grain is soaked for 16 to 24
hours, which allows it to absorb sufficient moisture for germination and for sprouts to appear. However,
germinated sorghum rootless and sprouts contain very large amounts of dhurrin, a cyanogenic glucoside,
which on hydrolysis produces a potent toxin variously known as prussic acid, hydrocyanic acid (HCN)
and cyanide. The fresh shoots and rootless of germinated sorghum and their extracts must therefore never
be consumed, either by people or by animals, except in very small quantities (e.g. when the germinated
grain is used just as a source of enzymes).
Malted sorghum has traditionally been used in several countries in Africa, but always after careful
removal of the toxic parts.
In the germination process, the grain produces a-amylase, an enzyme that converts insoluble starch to
soluble sugars. This has the effect of thinning paste made by heating a slurry of starch in water, in turn
allowing a higher caloric density in paste of a given viscosity, since as much as three times more flour can
be used when the grain has been germinated.
In India, malted finger millet is common and is considered to be superior to malted sorghum and malted
maize. Studies have shown that finger millet develops higher amylase activity than sorghum and other
millets. Germination of grain is reported to change the amino acid composition, convert starch into sugars
and improve the availability of fat, vitamins and minerals.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125052.
E-mail- [email protected]
Processing grain treated with alkali
To produce a particular type of tortilla that is popular in Mexico, sorghum grains are cooked in lime water
for a short time and steeped overnight, washed to remove the excess alkali and then ground to a paste.
Wood ash is used in traditional treatments to reduce the level of tannin in brown sorghums and improve
the nutritional quality. The sorghum is first soaked overnight in slurry of wood ash in water. After
draining it is left for three or four days to germinate. The germinated grains are sun-dried and pounded to
loosen the adhering wood ash and to remove the sprouts, with their high levels of cyanide. The grain is
then ground and used to prepare either a non-alcoholic beverage called obushara or an alcoholic drink
containing about 3 percent alcohol called omuramba.
Processing parboiled grain
Parboiling is reported to help in dehusking kodo millet and to eliminate the stickiness in cooked finger
millet porridge.
Industrial processing
Cereal grains can be milled wet, in the form of thin aqueous slurry, usually to produce starch, or in an
essentially dry form (often suitably dampened or "tempered") which usually produces meal (coarse or fine
flour).
In industrial processing, once the grain has been cleaned, the first operation is usually the separation of
offal (the portion not normally used for human consumption) from the edible portion. The offal consists of
the pericarp and sometimes the germ. Offal removal is frequently called decortication or dehulling.
Following the removal of offal, the edible portion is often milled to reduce the particle size of the edible
fraction. There is usually a choice of techniques and mills that may be used for particle size reduction if a
finer product is desired.
Three types of processors can be used to mill sorghum and millets on a commercial scale: abrasive
decorticators, which abrade the pericarp away, i.e. progressively remove offal from the outside; machines
that rub (rather than abrade) the pericarp off the endosperm; and roller mills, which cut the endosperm
from the inside of the pericarp.
Abrasive decortication
Abrasive decorticators work by abrading away the fibrous pericarp. Obviously, the outer layers of the
seed-coat are abraded away first and the innermost layers, which in many varieties contain those factors
that most need to be removed, are the last to be abraded away. If all parts of all grains could be abraded
away at the same rate, abrasive decortication would be an efficient way of removing the pericarp.
Rubbing techniques
E-mail- [email protected]
Processing grain treated with alkali
To produce a particular type of tortilla that is popular in Mexico, sorghum grains are cooked in lime water
for a short time and steeped overnight, washed to remove the excess alkali and then ground to a paste.
Wood ash is used in traditional treatments to reduce the level of tannin in brown sorghums and improve
the nutritional quality. The sorghum is first soaked overnight in slurry of wood ash in water. After
draining it is left for three or four days to germinate. The germinated grains are sun-dried and pounded to
loosen the adhering wood ash and to remove the sprouts, with their high levels of cyanide. The grain is
then ground and used to prepare either a non-alcoholic beverage called obushara or an alcoholic drink
containing about 3 percent alcohol called omuramba.
Processing parboiled grain
Parboiling is reported to help in dehusking kodo millet and to eliminate the stickiness in cooked finger
millet porridge.
Industrial processing
Cereal grains can be milled wet, in the form of thin aqueous slurry, usually to produce starch, or in an
essentially dry form (often suitably dampened or "tempered") which usually produces meal (coarse or fine
flour).
In industrial processing, once the grain has been cleaned, the first operation is usually the separation of
offal (the portion not normally used for human consumption) from the edible portion. The offal consists of
the pericarp and sometimes the germ. Offal removal is frequently called decortication or dehulling.
Following the removal of offal, the edible portion is often milled to reduce the particle size of the edible
fraction. There is usually a choice of techniques and mills that may be used for particle size reduction if a
finer product is desired.
Three types of processors can be used to mill sorghum and millets on a commercial scale: abrasive
decorticators, which abrade the pericarp away, i.e. progressively remove offal from the outside; machines
that rub (rather than abrade) the pericarp off the endosperm; and roller mills, which cut the endosperm
from the inside of the pericarp.
Abrasive decortication
Abrasive decorticators work by abrading away the fibrous pericarp. Obviously, the outer layers of the
seed-coat are abraded away first and the innermost layers, which in many varieties contain those factors
that most need to be removed, are the last to be abraded away. If all parts of all grains could be abraded
away at the same rate, abrasive decortication would be an efficient way of removing the pericarp.
Rubbing techniques
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125052.
E-mail- [email protected]
It is a new industrial milling process developed in Denmark, which does not involve abrasive milling.
Decortication is achieved by a steel rotor rotating the grain mass within a generally cylindrical chamber.
When the grain is properly tempered, the pericarp is rubbed off by the movement of one seed against
another.
Roller mills
Most wheat is milled in a type of mill called a roller mill. Roller mills are the most efficient mills for
separating the constituents of cereals. Two types of rollers are used: rollers with axial grooves, which cut
the endosperm from the pericarp (effectively cutting it away from the inside), and smooth rollers, which
progressively crush the endosperm pieces into finer and finer flour. Normally the grain is passed through a
number of roller mills, often 20 or more.
To withstand the stresses of roller milling, the pericarp of sorghum and millets has to be much moister
than that of wheat
Size reduction
Many mills can be used to reduce the size of the particles obtained by decortication, but the type that is
usually used (and is also probably the simplest to use and the cheapest to install) is the hammer mill. The
size of the holes in the screen determines the size of the particles of flour, but small holes will reduce the
throughput of the mill, and if they are too small overheating may result.
If roller mills are used for separating the endosperm from the offal, the particle size is usually reduced in
roller mills with smooth rollers.
E-mail- [email protected]
It is a new industrial milling process developed in Denmark, which does not involve abrasive milling.
Decortication is achieved by a steel rotor rotating the grain mass within a generally cylindrical chamber.
When the grain is properly tempered, the pericarp is rubbed off by the movement of one seed against
another.
Roller mills
Most wheat is milled in a type of mill called a roller mill. Roller mills are the most efficient mills for
separating the constituents of cereals. Two types of rollers are used: rollers with axial grooves, which cut
the endosperm from the pericarp (effectively cutting it away from the inside), and smooth rollers, which
progressively crush the endosperm pieces into finer and finer flour. Normally the grain is passed through a
number of roller mills, often 20 or more.
To withstand the stresses of roller milling, the pericarp of sorghum and millets has to be much moister
than that of wheat
Size reduction
Many mills can be used to reduce the size of the particles obtained by decortication, but the type that is
usually used (and is also probably the simplest to use and the cheapest to install) is the hammer mill. The
size of the holes in the screen determines the size of the particles of flour, but small holes will reduce the
throughput of the mill, and if they are too small overheating may result.
If roller mills are used for separating the endosperm from the offal, the particle size is usually reduced in
roller mills with smooth rollers.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125052.
E-mail- [email protected]
Chemical composition and nutritive value
TABLE 16: Nutrient content of whole kerneI and its fractions
a
Kernel
fraction
% of
kerne
l
weigh
t
Protein
b
(%)
Ash
(
%
)
Oil
(
%
)
Starch
(%)
Calcium
(mg/kg)
Phosphorus (mg/kg)Niacin (mg/100g)Riboflavin
(mg/100 g)
Pyridoxin
(mg/100g)
Sorghum
Whole kernel100 12.3 1.673.673.8 4.5 0.13 0.47
Endosperm82.3 12.3 0.370.682.5 4.4 0.09 0.40
(80) (20)(13)(94) (76) (50) (76)
Germ 9.8 18.9 10.428.113.4 8.1 0.39 0.72
(15) (69)(76)(20) (17) (28) (16)
Bran 7 9 6.7 2.04.934.6 4.4 0.40 0.44
(4 3) (11)(11)(4) (7) (22) (8)
Pearl millet
Whole kernel100 13.3 1.76.3 55 358
Endosperm75 10.9 0.320.53 17 240
(61) (14)(6) (25) (56)
Germ 17 24.5 7.232.2
(31) (71)(87)
Bran 8 17.1 3.25.0 168 442
(10) (15)(6) (36) (15)
E-mail- [email protected]
Chemical composition and nutritive value
TABLE 16: Nutrient content of whole kerneI and its fractions
a
Kernel
fraction
% of
kerne
l
weigh
t
Protein
b
(%)
Ash
(
%
)
Oil
(
%
)
Starch
(%)
Calcium
(mg/kg)
Phosphorus (mg/kg)Niacin (mg/100g)Riboflavin
(mg/100 g)
Pyridoxin
(mg/100g)
Sorghum
Whole kernel100 12.3 1.673.673.8 4.5 0.13 0.47
Endosperm82.3 12.3 0.370.682.5 4.4 0.09 0.40
(80) (20)(13)(94) (76) (50) (76)
Germ 9.8 18.9 10.428.113.4 8.1 0.39 0.72
(15) (69)(76)(20) (17) (28) (16)
Bran 7 9 6.7 2.04.934.6 4.4 0.40 0.44
(4 3) (11)(11)(4) (7) (22) (8)
Pearl millet
Whole kernel100 13.3 1.76.3 55 358
Endosperm75 10.9 0.320.53 17 240
(61) (14)(6) (25) (56)
Germ 17 24.5 7.232.2
(31) (71)(87)
Bran 8 17.1 3.25.0 168 442
(10) (15)(6) (36) (15)
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125052.
E-mail- [email protected]
a Values in parentheses represent percentage of whole kernel value.
b N × 6.25
Sources: Hubbard. Hall and Earle. 1950 (sorghum): Ahdelrahman. Hoseney and Varriano-Marston, 1984 (pearl millet).
E-mail- [email protected]
a Values in parentheses represent percentage of whole kernel value.
b N × 6.25
Sources: Hubbard. Hall and Earle. 1950 (sorghum): Ahdelrahman. Hoseney and Varriano-Marston, 1984 (pearl millet).
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125052.
E-mail- [email protected]
Sorghum and millets do not contain vitamin A, although certain yellowendosperm varieties contain small amounts of 13-carotene, a
precursor of vitamin A. No vitamin C is present in the raw millet grains.
Considerable variation in the grain composition of these cereals has been reported, particularly for sorghum and pearl millet
TABLE 17: Nutrient composition of sorghum, millets and other cereals (per 100 g edible portion; 12 percent moisture)
Food
Protein
a
(g)
Fat
(
g
)
Ash
(g
)
Crude
fibr
e (g)
Carhohydrate (g)
Energy
(kcal)
Ca
(m
g)
Fe (mg)
Thiamin
(mg
)
Riboflavin
(mg)
Niacin
(mg)
Rice (brown)7.9 2.71.31.0 76.0 362 33 1.8 0.410.04 4.3
Wheat 11.62.01.62.0 71.0 348 30 3.5 0.410.10 5.1
Maize 9.2 4.61.22.8 73.0 358 26 2.7 0.380.20 3.6
Sorghum 10.43.11.62.0 70.7 329 25 5.4 0.380.15 4.3
Pearl millet11.84.82.22.3 67.0 363 42 11.00.380.21 2.8
Finger millet7.7 1.52.63.6 72.6 336 350 3.9 0.420.19 1.1
Foxtail millet11.24.03.36.7 63.2 351 31 2.8 0.590.11 3.2
Common millet12.53.53.15.2 63.8 364 8 2.9 0.410.28 4.5
Little millet9.7 5.25.47.6 60.9 329 17 9.3 0.300.09 3.2
Barnyard millet11.03.94.513.655.0 300 22 18.60.330.10 4.2
Kodo millet9.8 3.63.35.2 66.6 353 35 1.7 0.150.09 2.0
a N x 6.25.
Sources: Hulse. Laing and Pearson. 1980: United States National Research Council/National Academy of Sciences. 1982.
USDA/HNIS. 1984.
E-mail- [email protected]
Sorghum and millets do not contain vitamin A, although certain yellowendosperm varieties contain small amounts of 13-carotene, a
precursor of vitamin A. No vitamin C is present in the raw millet grains.
Considerable variation in the grain composition of these cereals has been reported, particularly for sorghum and pearl millet
TABLE 17: Nutrient composition of sorghum, millets and other cereals (per 100 g edible portion; 12 percent moisture)
Food
Protein
a
(g)
Fat
(
g
)
Ash
(g
)
Crude
fibr
e (g)
Carhohydrate (g)
Energy
(kcal)
Ca
(m
g)
Fe (mg)
Thiamin
(mg
)
Riboflavin
(mg)
Niacin
(mg)
Rice (brown)7.9 2.71.31.0 76.0 362 33 1.8 0.410.04 4.3
Wheat 11.62.01.62.0 71.0 348 30 3.5 0.410.10 5.1
Maize 9.2 4.61.22.8 73.0 358 26 2.7 0.380.20 3.6
Sorghum 10.43.11.62.0 70.7 329 25 5.4 0.380.15 4.3
Pearl millet11.84.82.22.3 67.0 363 42 11.00.380.21 2.8
Finger millet7.7 1.52.63.6 72.6 336 350 3.9 0.420.19 1.1
Foxtail millet11.24.03.36.7 63.2 351 31 2.8 0.590.11 3.2
Common millet12.53.53.15.2 63.8 364 8 2.9 0.410.28 4.5
Little millet9.7 5.25.47.6 60.9 329 17 9.3 0.300.09 3.2
Barnyard millet11.03.94.513.655.0 300 22 18.60.330.10 4.2
Kodo millet9.8 3.63.35.2 66.6 353 35 1.7 0.150.09 2.0
a N x 6.25.
Sources: Hulse. Laing and Pearson. 1980: United States National Research Council/National Academy of Sciences. 1982.
USDA/HNIS. 1984.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125052.
E-mail- [email protected]
TABLE 18: Chemical composition of sorghum and pearl millet genotypes from the world germplasm collection at ICRISAT
a
Food
Protein
(%)
Fat
(%)
Ash
(%)
Crude
fibre
(%)
Starch
(%)
Amylose
sugar
Soluble
sugar
Reducing
sugar
Calcium
(mg/100g)
Phos
phorus
(mg/100 g)
Iron (mg/
100 g)
Sorghum
No. of
genotypes10 479160160100 160 80 160 80 99 99 99
Low 4.4 2.11.31.0 55.6 21.2 0.7 0.05 6 388 4.7
High 21.17.63.33.4 75.2 30.2 4.2 0.53 53 756 14.1
Mean 11.43.31.91.9 69.5 26.9 1.2 0.12 26 526 8.5
Pearl
millet
No. of
genotypes
20 704363636 44 44 36 16 27 27 27
Low 5.8 4.11.11.1 62.8 21.9 1.4 0.10 13 185 4.0
High 20.96.42.51.8 70.5 28.8 2.6 0.26 52 363 58.1
Mean 10.65.11.91.3 66.7 25.9 2.1 0.17 38 260 16.9
a All values except protein are expressed on a dry-weight basis.
Source: Jambunathan and Subramanian. 1988.
E-mail- [email protected]
TABLE 18: Chemical composition of sorghum and pearl millet genotypes from the world germplasm collection at ICRISAT
a
Food
Protein
(%)
Fat
(%)
Ash
(%)
Crude
fibre
(%)
Starch
(%)
Amylose
sugar
Soluble
sugar
Reducing
sugar
Calcium
(mg/100g)
Phos
phorus
(mg/100 g)
Iron (mg/
100 g)
Sorghum
No. of
genotypes10 479160160100 160 80 160 80 99 99 99
Low 4.4 2.11.31.0 55.6 21.2 0.7 0.05 6 388 4.7
High 21.17.63.33.4 75.2 30.2 4.2 0.53 53 756 14.1
Mean 11.43.31.91.9 69.5 26.9 1.2 0.12 26 526 8.5
Pearl
millet
No. of
genotypes
20 704363636 44 44 36 16 27 27 27
Low 5.8 4.11.11.1 62.8 21.9 1.4 0.10 13 185 4.0
High 20.96.42.51.8 70.5 28.8 2.6 0.26 52 363 58.1
Mean 10.65.11.91.3 66.7 25.9 2.1 0.17 38 260 16.9
a All values except protein are expressed on a dry-weight basis.
Source: Jambunathan and Subramanian. 1988.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 99 of 162
Carbohydrates
Starch is the major storage form of carbohydrate in sorghum and millets. It consists of amylopectin, a
branched-chain polymer of glucose, and amylose, a straight-chain polymer.
The digestibility of the starch, which depends on hydrolysis by pancreatic enzymes, determines the
available energy content of cereal grain. Processing of the grain by methods such as steaming,
pressure-cooking, flaking, puffing or micronization of the starch increases the digestibility of sorghum
starch.
On cooking, the gelatinized starch tends to return from the soluble, dispersed and amorphous state to
an insoluble crystalline state. This phenomenon is known as retrogradation or setback; it is enhanced
with low temperature and high concentration of starch. Amylose, the linear component of the starch, is
more susceptible to retrogradation.
Sorghum
With values ranging from 56 to 73 percent, the average starch content of sorghum is 69.5 percent.
About 70 to 80 percent of the sorghum starch is amylopectin and the remaining 20 to 30 percent is
amylose. Both genetic and environmental factors affect the amylose content of sorghum. Waxy or
glutenous sorghum varieties are very low in amylose; their starch is practically 100 percent
amylopectin. The textures of the grain endosperm, the particle size of the flour and starch digestibility
were found to be strongly correlated with each other. Starch in floury sorghum was found to be more
digestible than that in corneous sorghum.
The chemical nature of the starch, particularly the amylose and amylopectin content, is yet another
factor that affects its digestibility. The starch digestibility was reported to be higher in low-amylose,
i.e. waxy, sorghum than in normal sorghum, corn and pearl millet.
The gelatinization temperature of isolated sorghum starch and that of finely ground flour of the
corresponding endosperm has been reported to be the same. On the other hand the pasting
temperature, i.e. the temperature at which starch attains peak viscosity when heated with water to form
a paste, was found to be about 10°C higher for the sorghum flour than for the isolated starch.
Protein content and quality
The quality of a protein is primarily a function of its essential amino acid composition. Egg and
human milk proteins, for their very high biological value, have been considered as reference standards.
The most common feature was that Lysine was always found to be the most limiting amino acid. The
highest deficit of Lysine was in the protein of barnyard millet.
Lipid composition
Sorghum
Grain IsoleucineLeucineLysineMethionineCystinePhenylalaninaTyrosine ThreonineTryptophanValineChemical
score
Sorghum 245 832 12687 94 306 167 189 63 31337
Pearl millet256 598 214154 148 301 203 241 122 34563
Finger millet275 594 181194 163 325 - 263 191 41352
Foxtail millet475 1 044138175 - 419 - 194 61 43141
Common
millet
405 762 189160 - 307 - 147 49 40756
e-- [email protected] Page 99 of 162
Carbohydrates
Starch is the major storage form of carbohydrate in sorghum and millets. It consists of amylopectin, a
branched-chain polymer of glucose, and amylose, a straight-chain polymer.
The digestibility of the starch, which depends on hydrolysis by pancreatic enzymes, determines the
available energy content of cereal grain. Processing of the grain by methods such as steaming,
pressure-cooking, flaking, puffing or micronization of the starch increases the digestibility of sorghum
starch.
On cooking, the gelatinized starch tends to return from the soluble, dispersed and amorphous state to
an insoluble crystalline state. This phenomenon is known as retrogradation or setback; it is enhanced
with low temperature and high concentration of starch. Amylose, the linear component of the starch, is
more susceptible to retrogradation.
Sorghum
With values ranging from 56 to 73 percent, the average starch content of sorghum is 69.5 percent.
About 70 to 80 percent of the sorghum starch is amylopectin and the remaining 20 to 30 percent is
amylose. Both genetic and environmental factors affect the amylose content of sorghum. Waxy or
glutenous sorghum varieties are very low in amylose; their starch is practically 100 percent
amylopectin. The textures of the grain endosperm, the particle size of the flour and starch digestibility
were found to be strongly correlated with each other. Starch in floury sorghum was found to be more
digestible than that in corneous sorghum.
The chemical nature of the starch, particularly the amylose and amylopectin content, is yet another
factor that affects its digestibility. The starch digestibility was reported to be higher in low-amylose,
i.e. waxy, sorghum than in normal sorghum, corn and pearl millet.
The gelatinization temperature of isolated sorghum starch and that of finely ground flour of the
corresponding endosperm has been reported to be the same. On the other hand the pasting
temperature, i.e. the temperature at which starch attains peak viscosity when heated with water to form
a paste, was found to be about 10°C higher for the sorghum flour than for the isolated starch.
Protein content and quality
The quality of a protein is primarily a function of its essential amino acid composition. Egg and
human milk proteins, for their very high biological value, have been considered as reference standards.
The most common feature was that Lysine was always found to be the most limiting amino acid. The
highest deficit of Lysine was in the protein of barnyard millet.
Lipid composition
Sorghum
Grain IsoleucineLeucineLysineMethionineCystinePhenylalaninaTyrosine ThreonineTryptophanValineChemical
score
Sorghum 245 832 12687 94 306 167 189 63 31337
Pearl millet256 598 214154 148 301 203 241 122 34563
Finger millet275 594 181194 163 325 - 263 191 41352
Foxtail millet475 1 044138175 - 419 - 194 61 43141
Common
millet
405 762 189160 - 307 - 147 49 40756
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 100 of 162
The crude fat content of sorghum is 3 percent, which is higher than that of wheat and rice but lower
than that of maize. The germ and aleurone layers are the main contributors to the lipid fraction. The
germ itself provides about 80 percent of the total fat. As the kernel tat is mostly located in the germ, in
sorghum mutants with a large embryo fraction the fat content is higher (5.8 to 6.6 percent) than
normal.
Millets
Finger, foxtail and kodo millets appeared to contain less fat in the kernel than other millets, while the
fat content of common millet was similar to that of sorghum. The fat content of pearl millet is the
highest among the millets.
Minerals
The mineral composition of sorghum and millet grains (Table 25) is highly variable. More than
genetic factors, the environmental conditions prevailing in the growing region affect the mineral
content of these food grains.
Sorghum
In the sorghum kernel the mineral matter is unevenly distributed and is more concentrated in the germ
and the seed-coat. In milled sorghum flours minerals such as phosphorus, iron, zinc and copper
decreased with lower extraction rates. Similarly, pearling the grain to remove the fibrous seed-coat
resulted in considerable reduction in the mineral contents of sorghum.
TABLE 25: Mineral composition of sorghum and millets (mg %)
a
Grain Number of cultivarsP MgCaFeZn Cu MnMoCr
Sorghum 6 352 171154.22.50.441.150.060.017
Pearl millet9 379 137468.03.11.061.150.070.023
Finger millet6 320 1373983.92.30.475.490.100.028
Foxtail millet5
Whole 422 81385.32.91.600.85-0.070
Dehulled 360 68212.82.41.400.60-0.030
Common
millet
5
Whole 281 117234.02.45.801.20-0.040
Dehulled 156 7880.81.41.600.60-0.020
Little millet5
Whole 251 1331213.93.51.601.03-0.240
Dehulled 220 139139.33.71.000.68-0.180
Barnyard
millet
5
Whole 340 82219.22.61.301.33-0.140
Dehulled 267 39285.03.00.600.96-0.090
Kodo millet5
Whole 215 166313.61.55.802.90-0.080
e-- [email protected] Page 100 of 162
The crude fat content of sorghum is 3 percent, which is higher than that of wheat and rice but lower
than that of maize. The germ and aleurone layers are the main contributors to the lipid fraction. The
germ itself provides about 80 percent of the total fat. As the kernel tat is mostly located in the germ, in
sorghum mutants with a large embryo fraction the fat content is higher (5.8 to 6.6 percent) than
normal.
Millets
Finger, foxtail and kodo millets appeared to contain less fat in the kernel than other millets, while the
fat content of common millet was similar to that of sorghum. The fat content of pearl millet is the
highest among the millets.
Minerals
The mineral composition of sorghum and millet grains (Table 25) is highly variable. More than
genetic factors, the environmental conditions prevailing in the growing region affect the mineral
content of these food grains.
Sorghum
In the sorghum kernel the mineral matter is unevenly distributed and is more concentrated in the germ
and the seed-coat. In milled sorghum flours minerals such as phosphorus, iron, zinc and copper
decreased with lower extraction rates. Similarly, pearling the grain to remove the fibrous seed-coat
resulted in considerable reduction in the mineral contents of sorghum.
TABLE 25: Mineral composition of sorghum and millets (mg %)
a
Grain Number of cultivarsP MgCaFeZn Cu MnMoCr
Sorghum 6 352 171154.22.50.441.150.060.017
Pearl millet9 379 137468.03.11.061.150.070.023
Finger millet6 320 1373983.92.30.475.490.100.028
Foxtail millet5
Whole 422 81385.32.91.600.85-0.070
Dehulled 360 68212.82.41.400.60-0.030
Common
millet
5
Whole 281 117234.02.45.801.20-0.040
Dehulled 156 7880.81.41.600.60-0.020
Little millet5
Whole 251 1331213.93.51.601.03-0.240
Dehulled 220 139139.33.71.000.68-0.180
Barnyard
millet
5
Whole 340 82219.22.61.301.33-0.140
Dehulled 267 39285.03.00.600.96-0.090
Kodo millet5
Whole 215 166313.61.55.802.90-0.080
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 101 of 162
Dehulled 161 82200.50.71.601.10-0.020
a Expressed on a dry-weight basis.
Sources: Sankara Rao and Deosthale.1980 (sorghum) 1983 (pearl and finger millets), unpublished
( other millets).
Dietary fibre
The term dietary fibre is used to describe a variety of indigestible plant polysaccharides including
cellulose, hemicelluloses, pectins, oligosaccharides, gums and various lignified compounds.
According to the modified definition of Trowell (1976), dietary fibre is defined as the sum of the
lignin and polysaccharides that are not hydrolyzed by the endogenous enzymes of the human digestive
tract. Kamath and Belavady (1980) found that the major insoluble fibre component of sorghum was
cellulose, which varied from 1.19 to 5.23 percent in sorghum varieties. In any seed material there are
two sources of dietary fibre, namely the hull or the pericarp and the cell wall structural components.
The plant cell walls contain many non-carbohydrate components in addition to lignin, such as protein,
lipids and inorganic material, and they modify the properties of the polysaccharides.
Sorghum
Bach Knudsen and Munck (1985) found that a commonly consumed low tannin Sudanese sorghum
variety, Dabar, had total dietary fibre content of 7.6 percent while a high-tannin Sudanese variety,
Feterita, contained 9.2 percent. Cooking of the sorghum as whole-grain porridge decreased the
availability of energy, mostly because of the formation of enzyme-resistant starch, therefore
apparently increasing the dietary fibre content of both varieties. Compared to wheat, rye, barley or
maize, the total dietary fibre in the two sorghum varieties was low.
Dietary fibre has certain adverse effects on the availability of some nutrients. The concentration of
zinc and iron in the tibia of rats on sorghum diets rich in fibre and phytate was significantly lower than
in rats on a non-sorghum diet with low fibre content (All and Harland, 1991).
Decortication of the grain is one of the methods to remove fibre
Millets
The total dietary fibre in pearl millet (20.4 percent) and finger millet (18.6 percent) was higher than
that in sorghum (14.2 percent), wheat (17.2 percent) and rice (8.3 percent). Singh et al. (1987), also
using the Southgate method, found that the total dietary fibre content of pearl millet was 17 percent.
Culinary preparations
Foods from sorghum and millets can be grouped in two categories, traditional products and non-
traditional industrial products. Unprocessed or processed grain can be cooked whole or decorticated
and if necessary ground to flour by any of the traditional or industrial methods. They can be classified
broadly into breads, porridges, steamed products, boiled products, beverages and snack foods. The
various uses of sorghum and millets in India are shown in Table 28 (Pushpammannd Chittemma Rao,
1981). Foods from pearl millet in different parts of the world are given in Table 29; the products are
similar to those from sorghum. The following are a few of the many different ways sorghum and
millet can be prepared for eating. (Spices and condiments may be added to suit individual tastes.)
TABLE 28: Forms of utilization of sorghum and millets in India
e-- [email protected] Page 101 of 162
Dehulled 161 82200.50.71.601.10-0.020
a Expressed on a dry-weight basis.
Sources: Sankara Rao and Deosthale.1980 (sorghum) 1983 (pearl and finger millets), unpublished
( other millets).
Dietary fibre
The term dietary fibre is used to describe a variety of indigestible plant polysaccharides including
cellulose, hemicelluloses, pectins, oligosaccharides, gums and various lignified compounds.
According to the modified definition of Trowell (1976), dietary fibre is defined as the sum of the
lignin and polysaccharides that are not hydrolyzed by the endogenous enzymes of the human digestive
tract. Kamath and Belavady (1980) found that the major insoluble fibre component of sorghum was
cellulose, which varied from 1.19 to 5.23 percent in sorghum varieties. In any seed material there are
two sources of dietary fibre, namely the hull or the pericarp and the cell wall structural components.
The plant cell walls contain many non-carbohydrate components in addition to lignin, such as protein,
lipids and inorganic material, and they modify the properties of the polysaccharides.
Sorghum
Bach Knudsen and Munck (1985) found that a commonly consumed low tannin Sudanese sorghum
variety, Dabar, had total dietary fibre content of 7.6 percent while a high-tannin Sudanese variety,
Feterita, contained 9.2 percent. Cooking of the sorghum as whole-grain porridge decreased the
availability of energy, mostly because of the formation of enzyme-resistant starch, therefore
apparently increasing the dietary fibre content of both varieties. Compared to wheat, rye, barley or
maize, the total dietary fibre in the two sorghum varieties was low.
Dietary fibre has certain adverse effects on the availability of some nutrients. The concentration of
zinc and iron in the tibia of rats on sorghum diets rich in fibre and phytate was significantly lower than
in rats on a non-sorghum diet with low fibre content (All and Harland, 1991).
Decortication of the grain is one of the methods to remove fibre
Millets
The total dietary fibre in pearl millet (20.4 percent) and finger millet (18.6 percent) was higher than
that in sorghum (14.2 percent), wheat (17.2 percent) and rice (8.3 percent). Singh et al. (1987), also
using the Southgate method, found that the total dietary fibre content of pearl millet was 17 percent.
Culinary preparations
Foods from sorghum and millets can be grouped in two categories, traditional products and non-
traditional industrial products. Unprocessed or processed grain can be cooked whole or decorticated
and if necessary ground to flour by any of the traditional or industrial methods. They can be classified
broadly into breads, porridges, steamed products, boiled products, beverages and snack foods. The
various uses of sorghum and millets in India are shown in Table 28 (Pushpammannd Chittemma Rao,
1981). Foods from pearl millet in different parts of the world are given in Table 29; the products are
similar to those from sorghum. The following are a few of the many different ways sorghum and
millet can be prepared for eating. (Spices and condiments may be added to suit individual tastes.)
TABLE 28: Forms of utilization of sorghum and millets in India
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 102 of 162
Food Product type Form of grain used
Consumers
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Food Product type Form of grain used
Consumers
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 103 of 162
No. Percentage
Sorghum
Roti Unleavened flat breadFlour 1 132 67
SangatiStiff porridge Mixture of coarse
particles and flour
811 48
Annam Rice-like Dehulled grain 586 35
KudumuluSteamed Flour 295 18
Dosa Pancake Flour 213 13
Ambali Thin porridge Flour 167 10
BooreluDeep fried Flour 164 10
PelapindiPopped whole grain and
flour
Mixture of coarse
particles and flour
94 6
KarappoosaDeep fried Flour 42 3
Thapala
chakkalu
Shallow fried Flour 24 1
Pearl millet
Roti Unleavened bread Flour 706 88
SangatiStiff porridge Mixture of coarse
particles and flour
305 38
Annam Rice-like Dehulled grain 268 33
KudumuluSteamed Flour 229 29
BooreluDeep fried Flour 145 18
Dosa Pancake Flour 26 3
Thapala
chakkalu
Shallow fried Flour 24 3
Ambali Thin porridge Flour 22 3
Finger millet
SangatiStiff porridge Rice brokers and flour308 63
Roti Unleavened bread Flour 151 31
Ambali Thin porridge Flour 149 31
Proso millet
Annam Rice-like Dehulled grain 236 94
Muruku Deep fried Flour 96 38
KarappoosaDeep fried Flour 37 15
AriseluDeep fried Flour 17 7
Foxtail millet
Annam Rice-like Dehulled grain 517 96
AriseluDeep fried Flour 21 4
SangatiStiff porridge Flour 12 2
Roti Unleavened bread Flour 7 1
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No. Percentage
Sorghum
Roti Unleavened flat breadFlour 1 132 67
SangatiStiff porridge Mixture of coarse
particles and flour
811 48
Annam Rice-like Dehulled grain 586 35
KudumuluSteamed Flour 295 18
Dosa Pancake Flour 213 13
Ambali Thin porridge Flour 167 10
BooreluDeep fried Flour 164 10
PelapindiPopped whole grain and
flour
Mixture of coarse
particles and flour
94 6
KarappoosaDeep fried Flour 42 3
Thapala
chakkalu
Shallow fried Flour 24 1
Pearl millet
Roti Unleavened bread Flour 706 88
SangatiStiff porridge Mixture of coarse
particles and flour
305 38
Annam Rice-like Dehulled grain 268 33
KudumuluSteamed Flour 229 29
BooreluDeep fried Flour 145 18
Dosa Pancake Flour 26 3
Thapala
chakkalu
Shallow fried Flour 24 3
Ambali Thin porridge Flour 22 3
Finger millet
SangatiStiff porridge Rice brokers and flour308 63
Roti Unleavened bread Flour 151 31
Ambali Thin porridge Flour 149 31
Proso millet
Annam Rice-like Dehulled grain 236 94
Muruku Deep fried Flour 96 38
KarappoosaDeep fried Flour 37 15
AriseluDeep fried Flour 17 7
Foxtail millet
Annam Rice-like Dehulled grain 517 96
AriseluDeep fried Flour 21 4
SangatiStiff porridge Flour 12 2
Roti Unleavened bread Flour 7 1
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 104 of 162
Kodo millet
Annam Rice-like Dehulled grain 76 96
a Of surveyed consumers of each grain, percentage who consume the specified preparation. For
example, 67 percent of sorghum consumers reported that they consume sorghum prepared as roti.
Source: Pushpumma and Chittemma Rao, 1981.
Grits
Decorticated millet grains are sometimes boiled in water and served like rice. Grits made from
sorghum and pearl millet is also cooked like rice in many countries. Sorghum boiled like rice is called
kichuri in Bangladesh, lehta wagen in Botswana, kaoliang mifan in China, nifro in Ethiopia and Oka
baba in Nigeria (Subramanian et al., 1982). Dehulled sorghum and pearl millet grains are also cooked
like rice in India. A sorghum product similar to rice called sori has been developed in Mali. In China,
grain with 80 percent extraction rate is used for boiled sorghum. Sometimes pearled sorghum, rice and
beans are mixed and cooked. In some countries sorghum varieties with hard, small grains are specially
grown for processing into food which can be used as a substitute for rice.
TABLE 29: Traditional foods made with pearl millet
Type of food Common names Countries
Unfermented breadRoti, rotii India
Fermented breadKisra, dose, dosai, galletes, injera Africa, India
Thick porridgeUgali, tuwo, saino, dalaki, aceda, atap, bogobe, ting
tutu kalo, karo, kwon, nshimba, nuchu, to, tuo, zaafi,
asidah, mato, sadza, sangati
Africa, India
Thin porridgeUji, ambali, edi, eko, kamo, nasha, bwa kal, obushera
Ogi, oko, akamu, kafa, koko, akasa
Africa,India
Nigeria, Ghana
Steamed cooked
products
Couscous, degue West Africa
Boiled, rice like
foods
Annam, ache Africa, India
Snack foods Africa, Asia
Sweet/sour opaque
beers
Burukutu, dolo, pito, talla West Africa
Sour opaque beersMarisa, busaa, merissa, urwaga, mwenge, munkoyo,
utshwala, utywala, ikigage
Sudan, southern
Africa
Non-alcoholic
beverages
Mehewu, amaheu, marewa, magou, feting, abrey,
huswa
Africa
Source: Rooney and McDonough, 1987.
Flakes
Flaking is a process that is widely used for making foods from cereals, and both sorghum and millet
can be flaked. The flakes are further dried and can be stored for several months. Sorghum has been
flaked in the United States to improve its digestibility for beef cattle. In India poha and avilakki are
flaked foods based on sorghum and millet.
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Kodo millet
Annam Rice-like Dehulled grain 76 96
a Of surveyed consumers of each grain, percentage who consume the specified preparation. For
example, 67 percent of sorghum consumers reported that they consume sorghum prepared as roti.
Source: Pushpumma and Chittemma Rao, 1981.
Grits
Decorticated millet grains are sometimes boiled in water and served like rice. Grits made from
sorghum and pearl millet is also cooked like rice in many countries. Sorghum boiled like rice is called
kichuri in Bangladesh, lehta wagen in Botswana, kaoliang mifan in China, nifro in Ethiopia and Oka
baba in Nigeria (Subramanian et al., 1982). Dehulled sorghum and pearl millet grains are also cooked
like rice in India. A sorghum product similar to rice called sori has been developed in Mali. In China,
grain with 80 percent extraction rate is used for boiled sorghum. Sometimes pearled sorghum, rice and
beans are mixed and cooked. In some countries sorghum varieties with hard, small grains are specially
grown for processing into food which can be used as a substitute for rice.
TABLE 29: Traditional foods made with pearl millet
Type of food Common names Countries
Unfermented breadRoti, rotii India
Fermented breadKisra, dose, dosai, galletes, injera Africa, India
Thick porridgeUgali, tuwo, saino, dalaki, aceda, atap, bogobe, ting
tutu kalo, karo, kwon, nshimba, nuchu, to, tuo, zaafi,
asidah, mato, sadza, sangati
Africa, India
Thin porridgeUji, ambali, edi, eko, kamo, nasha, bwa kal, obushera
Ogi, oko, akamu, kafa, koko, akasa
Africa,India
Nigeria, Ghana
Steamed cooked
products
Couscous, degue West Africa
Boiled, rice like
foods
Annam, ache Africa, India
Snack foods Africa, Asia
Sweet/sour opaque
beers
Burukutu, dolo, pito, talla West Africa
Sour opaque beersMarisa, busaa, merissa, urwaga, mwenge, munkoyo,
utshwala, utywala, ikigage
Sudan, southern
Africa
Non-alcoholic
beverages
Mehewu, amaheu, marewa, magou, feting, abrey,
huswa
Africa
Source: Rooney and McDonough, 1987.
Flakes
Flaking is a process that is widely used for making foods from cereals, and both sorghum and millet
can be flaked. The flakes are further dried and can be stored for several months. Sorghum has been
flaked in the United States to improve its digestibility for beef cattle. In India poha and avilakki are
flaked foods based on sorghum and millet.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 105 of 162
Porridge
Porridges are the major foods in several African countries. They are either thick or thin in consistency.
These porridges carry different local names. Thick porridges are called uguli (Kenya, United Republic
of Tanzania, Uganda), to (Burkina Faso, the Niger), tuwo (Nigeria), aceda (the Sudan), bogobe, jwa
ting (Botswana) and sadza (Zimbabwe).
TABLE 30: Chemical composition of whole and decorticated sorghum grains and dishes
a
Variety and
preparation
Protein
(N×6.25)
Ash
(%
w/w)
Fat
(%w/w)
Crude fibre
(% w/w)
Such+sugar
(% w/w)
Tetron, whole grain10.9 1.785.1 2.1 72.5
Dabar, whole grain11.6 1.684.0 2.0 73.4
Feterita, whole grain13.4 2.074.1 2.1 71.0
Dabar, decorticaded
(79% extraction)
11,3 1.393.3 1.0 79.4
Feterita, decorticated
(80% extraction)
14.9 0.872.7 0.8 74.3
Dabar, ugali, whole
grain
11.3 1.564.1 2.2 69.9
Dabar, ugali
(acid),whole grain
12.7 1.623.8 2.2 69.7
Feterita, ugali,
whole grain
14.1 1.394.0 2.2 66.5
Tetron, kisra, whole
grain
11.3 1.805.3 2.1 71.2
Feterita, kisra,
whole grain
14.1 1.595.1 2.4 68.8
Dabar, kisra,
decorticated (79%
extraction)
12.6 1.234.2 1.1 74.8
a All data are expressed on a dry - matter basis.
Source: Eggum et al., 1983.
The chibuku beer consumed in southern Africa is basically a thin fermented porridge, usually made
from sorghum.
Breads and other baked products
Flat breads are made by baking batters made with flour and water on a hot pan or griddle. Almost any
flour may be used. The batter can be based on sorghum, millet or any other cereal and it may or may
e-- [email protected] Page 105 of 162
Porridge
Porridges are the major foods in several African countries. They are either thick or thin in consistency.
These porridges carry different local names. Thick porridges are called uguli (Kenya, United Republic
of Tanzania, Uganda), to (Burkina Faso, the Niger), tuwo (Nigeria), aceda (the Sudan), bogobe, jwa
ting (Botswana) and sadza (Zimbabwe).
TABLE 30: Chemical composition of whole and decorticated sorghum grains and dishes
a
Variety and
preparation
Protein
(N×6.25)
Ash
(%
w/w)
Fat
(%w/w)
Crude fibre
(% w/w)
Such+sugar
(% w/w)
Tetron, whole grain10.9 1.785.1 2.1 72.5
Dabar, whole grain11.6 1.684.0 2.0 73.4
Feterita, whole grain13.4 2.074.1 2.1 71.0
Dabar, decorticaded
(79% extraction)
11,3 1.393.3 1.0 79.4
Feterita, decorticated
(80% extraction)
14.9 0.872.7 0.8 74.3
Dabar, ugali, whole
grain
11.3 1.564.1 2.2 69.9
Dabar, ugali
(acid),whole grain
12.7 1.623.8 2.2 69.7
Feterita, ugali,
whole grain
14.1 1.394.0 2.2 66.5
Tetron, kisra, whole
grain
11.3 1.805.3 2.1 71.2
Feterita, kisra,
whole grain
14.1 1.595.1 2.4 68.8
Dabar, kisra,
decorticated (79%
extraction)
12.6 1.234.2 1.1 74.8
a All data are expressed on a dry - matter basis.
Source: Eggum et al., 1983.
The chibuku beer consumed in southern Africa is basically a thin fermented porridge, usually made
from sorghum.
Breads and other baked products
Flat breads are made by baking batters made with flour and water on a hot pan or griddle. Almost any
flour may be used. The batter can be based on sorghum, millet or any other cereal and it may or may
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 106 of 162
not be fermented. These flat breads are known by many local names: roti and charpatti in India, tuwo
in parts of Nigeria, tortillas in Central America, etc.
Unfermented breads include roti and tortillas. Roti and chapatti made from sorghum or millets are
common foods in India, Bangladesh, Pakistan and Arab countries. More than 70 percent of sorghum
grown in India is used for making roti (Murty and Subramanian, 1982).
Tortillas, which are prepared in Mexico and Central America, are similar to roti except that the grain is
lime-cooked and wet milled.
Pasta and noodles
Pasta products (noodles) such as spaghetti and macaroni are usually made from semolina or from flour
of durum wheat or common wheat or a mixture of both. Wheat has a unique property of forming an
extensible, elastic and cohesive mass when mixed with water. Sorghum and millet flours lack these
properties when used alone.
Sorghum is inferior to wheat for making pasta, both because it contains no gluten and because its
gelatinization temperature is higher than that of wheat.
Nutritional inhibitors and toxic factors
As with other foodstuffs certain nutritional inhibitors and toxic substances are associated with
sorghum and millet grains. Antinutritional factors can be classified broadly as those naturally present
in the grains and those due to contamination which may be of fungal origin or may be related to soil
and other environmental influences. These factors modify the nutritional value of the individual
grains, and some of them have very serious consequences. The following is a brief account of some of
the antinutrients and toxic substances associated with sorghum and millets.
Phytate
Phytate represents a complex class of naturally occurring phosphorus compounds that can
significantly influence the functional and nutritional properties of foods. Although the presence of
these compounds has been known for over a century, their biological role is not completely
understood. Phytic acid is the main phosphorus store in mature seeds. Phytic acid has a strong binding
capacity, readily forming complexes with multivalent cations and proteins. Most of the phytate-metal
complexes are insoluble at physiological pH. Hence phytate binding renders several minerals
biologically unavailable to animals and humans.
Polyphenols
Widely distributed polyphenols in plants are not directly involved in any metabolic process and are
therefore considered secondary metabolites. Some polyphenolic compounds have a role as defence
chemicals, protecting the plant from predatory attacks of herbivores, pathogenic fungi and parasitic
weeds. Polyphenols in the grains also prevent grain losses from premature germination and damage
due to mould.
Digestive enzyme inhibitors
Inhibitors of amylases and proteases have been identified in sorghum and some millets screened millet
varieties for inhibitory activity against human salivary amylase. Sorghum had the highest inhibitory
activity against human, bovine and porcine amylases; foxtail millet did not inhibit human pancreatic
amylase, while extracts from pearl and finger millets inhibited all a-amylases tested.
e-- [email protected] Page 106 of 162
not be fermented. These flat breads are known by many local names: roti and charpatti in India, tuwo
in parts of Nigeria, tortillas in Central America, etc.
Unfermented breads include roti and tortillas. Roti and chapatti made from sorghum or millets are
common foods in India, Bangladesh, Pakistan and Arab countries. More than 70 percent of sorghum
grown in India is used for making roti (Murty and Subramanian, 1982).
Tortillas, which are prepared in Mexico and Central America, are similar to roti except that the grain is
lime-cooked and wet milled.
Pasta and noodles
Pasta products (noodles) such as spaghetti and macaroni are usually made from semolina or from flour
of durum wheat or common wheat or a mixture of both. Wheat has a unique property of forming an
extensible, elastic and cohesive mass when mixed with water. Sorghum and millet flours lack these
properties when used alone.
Sorghum is inferior to wheat for making pasta, both because it contains no gluten and because its
gelatinization temperature is higher than that of wheat.
Nutritional inhibitors and toxic factors
As with other foodstuffs certain nutritional inhibitors and toxic substances are associated with
sorghum and millet grains. Antinutritional factors can be classified broadly as those naturally present
in the grains and those due to contamination which may be of fungal origin or may be related to soil
and other environmental influences. These factors modify the nutritional value of the individual
grains, and some of them have very serious consequences. The following is a brief account of some of
the antinutrients and toxic substances associated with sorghum and millets.
Phytate
Phytate represents a complex class of naturally occurring phosphorus compounds that can
significantly influence the functional and nutritional properties of foods. Although the presence of
these compounds has been known for over a century, their biological role is not completely
understood. Phytic acid is the main phosphorus store in mature seeds. Phytic acid has a strong binding
capacity, readily forming complexes with multivalent cations and proteins. Most of the phytate-metal
complexes are insoluble at physiological pH. Hence phytate binding renders several minerals
biologically unavailable to animals and humans.
Polyphenols
Widely distributed polyphenols in plants are not directly involved in any metabolic process and are
therefore considered secondary metabolites. Some polyphenolic compounds have a role as defence
chemicals, protecting the plant from predatory attacks of herbivores, pathogenic fungi and parasitic
weeds. Polyphenols in the grains also prevent grain losses from premature germination and damage
due to mould.
Digestive enzyme inhibitors
Inhibitors of amylases and proteases have been identified in sorghum and some millets screened millet
varieties for inhibitory activity against human salivary amylase. Sorghum had the highest inhibitory
activity against human, bovine and porcine amylases; foxtail millet did not inhibit human pancreatic
amylase, while extracts from pearl and finger millets inhibited all a-amylases tested.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 107 of 162
Similar screening for protease inhibitors showed that kodo, common and little millet varieties had no
pro/ease-inhibitory properties while pearl, foxtail and barnyard millets displayed only antitrypsin
activity.
Goitrogens
Iodine is an essential micronutrient for all animal species, and iodine deficiency is among the most
widely prevalent nutritional problems in many developing countries. Though environmental iodine
deficiency is a prerequisite to goitre formation, the incidence of goitre in animals and humans with
normal dietary intake of iodine.
Another staple food implicated in the aetiology of goitre is pearl millet. A positive correlation
observed between the incidence of goitre and per caput production of pearl millet in six African
countries.
Mycotoxins
Like other cereals, sorghum and millets are susceptible to fungal growth and mycotoxin production
under certain environmental conditions. Mycotoxins not only threaten consumer health but also affect
food quality, causing huge economic losses.
Storage fungi, mostly of the genera Aspergillus and Penicillium, are found on foodgrain stored with
moisture content greater than 13 percent (Sauer, 1988). Mouldy sorghum earheads were shown to be
contaminated with aflatoxins B and G in India.
Conclusion
Several factors as discussed above affect the nutritional quality of sorghum and millets. Fortunately
there are methods available to eliminate, inactivate or prevent the antinutritional and/or toxic
principles that may be present naturally or because of contamination. Grain processing, discussed in
Chapter 3, has a significant role.
Some recipes based on sorghum and millets
1. UJI
Thin porridge
Method
1.Mix the flour with about 1/2 cup water.
2.Place in a covered container and allow to ferment 24 to 48 hours in a warm place. Omit this
step for an unfermented product.
3.Boil remaining water and add fermented flour to it.
4.Cook for 10 to 15 minutes until smooth and thick.
5.Add sour milk (or water or banana juice), stir and boil for another 2 minutes.
6.Add sugar and serve hot at breakfast or lunch. Serves 2-3.
Notes
A light colour, smooth, flowing, creamy consistency and bland to sour taste and aroma are preferred.
A dark, lumpy, grainy product with off flavour is not desired.
Kenya
United Republic of Tanzania
Uganda
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Similar screening for protease inhibitors showed that kodo, common and little millet varieties had no
pro/ease-inhibitory properties while pearl, foxtail and barnyard millets displayed only antitrypsin
activity.
Goitrogens
Iodine is an essential micronutrient for all animal species, and iodine deficiency is among the most
widely prevalent nutritional problems in many developing countries. Though environmental iodine
deficiency is a prerequisite to goitre formation, the incidence of goitre in animals and humans with
normal dietary intake of iodine.
Another staple food implicated in the aetiology of goitre is pearl millet. A positive correlation
observed between the incidence of goitre and per caput production of pearl millet in six African
countries.
Mycotoxins
Like other cereals, sorghum and millets are susceptible to fungal growth and mycotoxin production
under certain environmental conditions. Mycotoxins not only threaten consumer health but also affect
food quality, causing huge economic losses.
Storage fungi, mostly of the genera Aspergillus and Penicillium, are found on foodgrain stored with
moisture content greater than 13 percent (Sauer, 1988). Mouldy sorghum earheads were shown to be
contaminated with aflatoxins B and G in India.
Conclusion
Several factors as discussed above affect the nutritional quality of sorghum and millets. Fortunately
there are methods available to eliminate, inactivate or prevent the antinutritional and/or toxic
principles that may be present naturally or because of contamination. Grain processing, discussed in
Chapter 3, has a significant role.
Some recipes based on sorghum and millets
1. UJI
Thin porridge
Method
1.Mix the flour with about 1/2 cup water.
2.Place in a covered container and allow to ferment 24 to 48 hours in a warm place. Omit this
step for an unfermented product.
3.Boil remaining water and add fermented flour to it.
4.Cook for 10 to 15 minutes until smooth and thick.
5.Add sour milk (or water or banana juice), stir and boil for another 2 minutes.
6.Add sugar and serve hot at breakfast or lunch. Serves 2-3.
Notes
A light colour, smooth, flowing, creamy consistency and bland to sour taste and aroma are preferred.
A dark, lumpy, grainy product with off flavour is not desired.
Kenya
United Republic of Tanzania
Uganda
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 108 of 162
Ingredients
1 cup sorghum or millet flour
3-4 cups water
1 cup sour milk, water or banana juice
2 tablespoons sugar, or salt or lemon juice to taste
2. AMBALI
Stiff porridge
Method
1.Bring water to boil.
2.Mix the flour in cold water.
3.Add to the boiling water in small amounts.
4.Stir to prevent lump formation.
5.Cook until thick.
6.Leave overnight to ferment.
7.Add water or buttermilk. Mix well and serve.
India
Ingredients
1 litre water
250 g sorghum or millet flour
Salt to taste
Buttermilk (optional)
3. SANKATI
Stiff porridge
Method
1.Sieve the flour through a 20-mesh sieve and separate grits from fine flour.
2.Boil water in a vessel.
3.Add grits to the boiling water while stirring.
4.Continue boiling and after 10 minutes gradually add the fine flour.
5.Continue stirring and cooking for another few minutes.
6.Pour the sankati on to a moist plate and prepare balls of approximately 10 cm diameter by
hand.
7.Serve fresh with sauce, dhal, pickles, chutneys, buttermilk, curd, vegetable curries, etc.
according to taste.
Notes
Sankati should be light in colour and slightly sweet in taste. It should not be sticky or pasty and should
remain firm when stored in water.
India
Ingredients
Coarsely ground whole-grain sorghum flour, winnowed and free of bran
Water
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Ingredients
1 cup sorghum or millet flour
3-4 cups water
1 cup sour milk, water or banana juice
2 tablespoons sugar, or salt or lemon juice to taste
2. AMBALI
Stiff porridge
Method
1.Bring water to boil.
2.Mix the flour in cold water.
3.Add to the boiling water in small amounts.
4.Stir to prevent lump formation.
5.Cook until thick.
6.Leave overnight to ferment.
7.Add water or buttermilk. Mix well and serve.
India
Ingredients
1 litre water
250 g sorghum or millet flour
Salt to taste
Buttermilk (optional)
3. SANKATI
Stiff porridge
Method
1.Sieve the flour through a 20-mesh sieve and separate grits from fine flour.
2.Boil water in a vessel.
3.Add grits to the boiling water while stirring.
4.Continue boiling and after 10 minutes gradually add the fine flour.
5.Continue stirring and cooking for another few minutes.
6.Pour the sankati on to a moist plate and prepare balls of approximately 10 cm diameter by
hand.
7.Serve fresh with sauce, dhal, pickles, chutneys, buttermilk, curd, vegetable curries, etc.
according to taste.
Notes
Sankati should be light in colour and slightly sweet in taste. It should not be sticky or pasty and should
remain firm when stored in water.
India
Ingredients
Coarsely ground whole-grain sorghum flour, winnowed and free of bran
Water
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
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4. ROTI
Unleavened thin flat bread
Method
1.Mix flour, water and salt to form a firm dough. Knead it thoroughly.
2.Shape it into a ball.
3.Sprinkle some dry flour on a wooden board and place the dough ball on it. Flatten the dough
by hand, pressing into a circle of fairly even thickness.
4.Bake the flat dough on a hot shallow pan or grill. After about half a minute, sprinkle water on
the baking dough.
5.Turn the rob over and bake it on the other side for 30 seconds or until it puffs.
6.Serve it with pickles, chutneys, dhal or vegetable sauces.
Notes
A thin, soft, light-coloured roti is preferred. For up to 24 hours of storage it should remain soft. A dark
product is not desired.
India
Ingredients
Whole-grain sorghum or pearl millet flour
Water
Salt to taste
Oil (optional)
5. TORTILLAS
Unfermented bread
Method
1.Prepare mesa by mixing lime solution and sorghum grain in 3:1 proportion and cooking for 3
to 10 minutes at the boiling point.
2.Steep for at least 4 hours.
3.Prepare balls from the mesa and press them into circles of about 15 cm diameter and 0.5 cm
thickness.
4.Cook the tortillas on a grill or a traditional clay comale.
5.During cooking turn the tortilla once to brown it lightly on both sides.
6.Leave the cooked tortillas on the floor to cool a little, then keep them in a container lined with
a cloth to cover.
Notes
Sorghum tortillas are off coloured compared to those made with white maize. A tortilla prepared from
a 1:1 mix of sorghum and maize is well accepted.
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4. ROTI
Unleavened thin flat bread
Method
1.Mix flour, water and salt to form a firm dough. Knead it thoroughly.
2.Shape it into a ball.
3.Sprinkle some dry flour on a wooden board and place the dough ball on it. Flatten the dough
by hand, pressing into a circle of fairly even thickness.
4.Bake the flat dough on a hot shallow pan or grill. After about half a minute, sprinkle water on
the baking dough.
5.Turn the rob over and bake it on the other side for 30 seconds or until it puffs.
6.Serve it with pickles, chutneys, dhal or vegetable sauces.
Notes
A thin, soft, light-coloured roti is preferred. For up to 24 hours of storage it should remain soft. A dark
product is not desired.
India
Ingredients
Whole-grain sorghum or pearl millet flour
Water
Salt to taste
Oil (optional)
5. TORTILLAS
Unfermented bread
Method
1.Prepare mesa by mixing lime solution and sorghum grain in 3:1 proportion and cooking for 3
to 10 minutes at the boiling point.
2.Steep for at least 4 hours.
3.Prepare balls from the mesa and press them into circles of about 15 cm diameter and 0.5 cm
thickness.
4.Cook the tortillas on a grill or a traditional clay comale.
5.During cooking turn the tortilla once to brown it lightly on both sides.
6.Leave the cooked tortillas on the floor to cool a little, then keep them in a container lined with
a cloth to cover.
Notes
Sorghum tortillas are off coloured compared to those made with white maize. A tortilla prepared from
a 1:1 mix of sorghum and maize is well accepted.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
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Phaseolus vulgaris
Plant with immature fruit
Scientific classification
Kingdom: Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order: Fabales
Family:Fabaceae
Subfamily:Faboideae
Tribe:Phaseoleae
Genus: Phaseolus
Species:P. vulgaris
Binomial name
Phaseolus vulgaris
L.
Green pole beans on beanpoles
Pinto or mottled beans
Pinto beans
Alubia pinta alavesa
White beans
Red (kidney) beans
Red Kidney beans
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Phaseolus vulgaris
Plant with immature fruit
Scientific classification
Kingdom: Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order: Fabales
Family:Fabaceae
Subfamily:Faboideae
Tribe:Phaseoleae
Genus: Phaseolus
Species:P. vulgaris
Binomial name
Phaseolus vulgaris
L.
Green pole beans on beanpoles
Pinto or mottled beans
Pinto beans
Alubia pinta alavesa
White beans
Red (kidney) beans
Red Kidney beans
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
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Black beans
Black beans
Lima bean
Lima beans
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Subfamily:Faboideae
Tribe:Phaseoleae
Genus:Phaseolus
Species:P. lunatus
Binomial name
Phaseolus lunatus
L.
Phaseolus lunatus is a legume. It is grown for
its seed, which is eaten as a vegetable. It is
commonly known as the lima bean or butter
bean, it is also known as Haba bean, Pallar
bean, Burma bean, Guffin bean, Hibbert bean,
Java bean, Sieva bean, Rangood bean,
Madagascar bean, Paiga, Paigya, prolific
bean, civet bean and sugar bean.
Azuki bean
Azuki beans
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Subfamily:Faboideae
Tribe:Phaseoleae
Genus:Vigna
Species:V. angularis
Binomial name
Vigna angularis
(Willd.) Ohwi & H. Ohashi
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Black beans
Black beans
Lima bean
Lima beans
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Subfamily:Faboideae
Tribe:Phaseoleae
Genus:Phaseolus
Species:P. lunatus
Binomial name
Phaseolus lunatus
L.
Phaseolus lunatus is a legume. It is grown for
its seed, which is eaten as a vegetable. It is
commonly known as the lima bean or butter
bean, it is also known as Haba bean, Pallar
bean, Burma bean, Guffin bean, Hibbert bean,
Java bean, Sieva bean, Rangood bean,
Madagascar bean, Paiga, Paigya, prolific
bean, civet bean and sugar bean.
Azuki bean
Azuki beans
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Subfamily:Faboideae
Tribe:Phaseoleae
Genus:Vigna
Species:V. angularis
Binomial name
Vigna angularis
(Willd.) Ohwi & H. Ohashi
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
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Mung bean
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Genus:Vigna
Species:V. radiata
Binomial name
Vigna radiata
(L.) R. Wilczek
Synonyms
Phaeolus aureus Roxb.
Urad bean
Dry urad beans
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Subfamily:Faboideae
Tribe:Phaseoleae
Genus:Vigna
Species:V. mungo
Binomial name
Vigna mungo
(L.) Hepper
White lentils
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Mung bean
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Genus:Vigna
Species:V. radiata
Binomial name
Vigna radiata
(L.) R. Wilczek
Synonyms
Phaeolus aureus Roxb.
Urad bean
Dry urad beans
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Subfamily:Faboideae
Tribe:Phaseoleae
Genus:Vigna
Species:V. mungo
Binomial name
Vigna mungo
(L.) Hepper
White lentils
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
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Runner bean
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Subfamily:Faboideae
Tribe:Phaseoleae
Genus:Phaseolus
Species:P. coccineus
Binomial name
Phaseolus coccineus
L.
Rice bean
Harvested Vigna umbellata beans
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Subfamily:Faboideae
Tribe:Phaseoleae
Genus:Vigna
Species:V. umbellata
Binomial name
Vigna umbellata
(Thunb.) Ohwi & H. Ohashi
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Runner bean
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Subfamily:Faboideae
Tribe:Phaseoleae
Genus:Phaseolus
Species:P. coccineus
Binomial name
Phaseolus coccineus
L.
Rice bean
Harvested Vigna umbellata beans
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Subfamily:Faboideae
Tribe:Phaseoleae
Genus:Vigna
Species:V. umbellata
Binomial name
Vigna umbellata
(Thunb.) Ohwi & H. Ohashi
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
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Moth bean
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Subfamily:Faboideae
Tribe:Phaseoleae
Genus:Vigna
Species:V. aconitifolia
Binomial name
Vigna aconitifolia
(Jacq.) Marechal
Synonyms
Phaseolus aconitifolius Jacq.
Tepary bean
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Subfamily:Faboideae
Tribe:Phaseoleae
Genus:Phaseolus
Species:P. acutifolius
Binomial name
Phaseolus acutifolius
A. Gray
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Moth bean
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Subfamily:Faboideae
Tribe:Phaseoleae
Genus:Vigna
Species:V. aconitifolia
Binomial name
Vigna aconitifolia
(Jacq.) Marechal
Synonyms
Phaseolus aconitifolius Jacq.
Tepary bean
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Subfamily:Faboideae
Tribe:Phaseoleae
Genus:Phaseolus
Species:P. acutifolius
Binomial name
Phaseolus acutifolius
A. Gray
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
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Vicia faba
Vicia faba plants in flower
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Subfamily:Faboideae
Tribe:Vicieae
Genus:Vicia
Species:V. faba
Binomial name
Vicia faba
L.
Pea
Peas are contained within a pod
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Subfamily:Faboideae
Tribe:Vicieae
Genus:Pisum
Species:P. sativum
Binomial name
Pisum sativum
L.
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Vicia faba
Vicia faba plants in flower
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Subfamily:Faboideae
Tribe:Vicieae
Genus:Vicia
Species:V. faba
Binomial name
Vicia faba
L.
Pea
Peas are contained within a pod
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Subfamily:Faboideae
Tribe:Vicieae
Genus:Pisum
Species:P. sativum
Binomial name
Pisum sativum
L.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
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Chickpea
Left: Bengal variety; right: European
variety
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Subfamily:Faboideae
Genus:Cicer
Species:C. arietinum
Binomial name
Cicer arietinum
L.
Cowpea
Black-eyed peas
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Subfamily:Faboideae
Genus:Vigna
Species:V. unguiculata
Binomial name
Vigna unguiculata
(L.) Walp.
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Chickpea
Left: Bengal variety; right: European
variety
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Subfamily:Faboideae
Genus:Cicer
Species:C. arietinum
Binomial name
Cicer arietinum
L.
Cowpea
Black-eyed peas
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Subfamily:Faboideae
Genus:Vigna
Species:V. unguiculata
Binomial name
Vigna unguiculata
(L.) Walp.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
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Pigeon pea
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Genus:Cajanus
Species:C. cajan
Binomial name
Cajanus cajan
(L.) Millsp.
Pigeon peas seeds
Pigeon peas from Trinidad and Tobago
Lentil
Lentils
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Subfamily:Faboideae
Tribe:Vicieae
Genus:Lens
Species:L. culinaris
Binomial name
Lens culinaris
Medikus
Illustration of the lentil plant, 1885
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Pigeon pea
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Genus:Cajanus
Species:C. cajan
Binomial name
Cajanus cajan
(L.) Millsp.
Pigeon peas seeds
Pigeon peas from Trinidad and Tobago
Lentil
Lentils
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Subfamily:Faboideae
Tribe:Vicieae
Genus:Lens
Species:L. culinaris
Binomial name
Lens culinaris
Medikus
Illustration of the lentil plant, 1885
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
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Bambara groundnut
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Subfamily:Faboideae
Tribe:Phaseoleae
Genus:Vigna
Species:V. subterranea
Binomial name
Vigna subterranea
(L.) Verdc.
Vicia
Vicia grandiflora
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Subfamily:Faboideae
Tribe:Vicieae
Genus:Vicia
Species
About 140 species, including:
Vicia americana (American Vetch)
Vicia articulata Hornem. (Bard
Vetch)
Vicia bithynica (Bithynian Vetch)
Vicia canescens
Vicia cassubica (Danzig Vetch)
Vicia cracca (Tufted Vetch)
Vicia dumetorum
Vicia ervilia (Bitter Vetch)
Vicia faba (Broad Bean)
Vicia lathyroides (Spring Vetch)
Vicia lutea (Yellow Vetch)
Vicia pyrenaica
Vicia sativa (Common Vetch)
Vicia sepium (Bush Vetch)
Vicia sylvatica (Wood Vetch)
Vicia tenuifolia (Fine-leaved Vetch)
Vicia tenuissima (Slender Vetch)
Vicia tetrasperma (Smooth Vetch)
Vicia unijuga
Vicia villosa (Hairy or Fodder
Vetch)
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Bambara groundnut
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Subfamily:Faboideae
Tribe:Phaseoleae
Genus:Vigna
Species:V. subterranea
Binomial name
Vigna subterranea
(L.) Verdc.
Vicia
Vicia grandiflora
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Subfamily:Faboideae
Tribe:Vicieae
Genus:Vicia
Species
About 140 species, including:
Vicia americana (American Vetch)
Vicia articulata Hornem. (Bard
Vetch)
Vicia bithynica (Bithynian Vetch)
Vicia canescens
Vicia cassubica (Danzig Vetch)
Vicia cracca (Tufted Vetch)
Vicia dumetorum
Vicia ervilia (Bitter Vetch)
Vicia faba (Broad Bean)
Vicia lathyroides (Spring Vetch)
Vicia lutea (Yellow Vetch)
Vicia pyrenaica
Vicia sativa (Common Vetch)
Vicia sepium (Bush Vetch)
Vicia sylvatica (Wood Vetch)
Vicia tenuifolia (Fine-leaved Vetch)
Vicia tenuissima (Slender Vetch)
Vicia tetrasperma (Smooth Vetch)
Vicia unijuga
Vicia villosa (Hairy or Fodder
Vetch)
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
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Lupin
Wild Perennial Lupin (Lupinus perennis)
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Subfamily:Faboideae
Tribe:Luppineae
Genus:Lupinus
L.
Subgenus:Lupinus and Platycarpos
(Wats.) Kurl.
Species
150-200 species, including:
Lupinus albus
Lupinus angustifolius
Lupinus luteus
Lupinus albifrons
Lupinus arboreus
Lupinus aridorum
Lupinus arizonicus
Lupinus benthamii
Lupinus bicolor
Lupinus diffusus
Lupinus microcarpus
Lupinus mutabilis
Lupinus nanus
Lupinus polyphyllus
Lupinus texensis
Hyacinth bean
Hyacinth bean plant
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Subfamily:Faboideae
Tribe:Phaseoleae
Genus:Lablab
Species:L. purpureus
Binomial name
Lablab purpureus
(L.) Sweet
hyacinth beans
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Lupin
Wild Perennial Lupin (Lupinus perennis)
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Subfamily:Faboideae
Tribe:Luppineae
Genus:Lupinus
L.
Subgenus:Lupinus and Platycarpos
(Wats.) Kurl.
Species
150-200 species, including:
Lupinus albus
Lupinus angustifolius
Lupinus luteus
Lupinus albifrons
Lupinus arboreus
Lupinus aridorum
Lupinus arizonicus
Lupinus benthamii
Lupinus bicolor
Lupinus diffusus
Lupinus microcarpus
Lupinus mutabilis
Lupinus nanus
Lupinus polyphyllus
Lupinus texensis
Hyacinth bean
Hyacinth bean plant
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Subfamily:Faboideae
Tribe:Phaseoleae
Genus:Lablab
Species:L. purpureus
Binomial name
Lablab purpureus
(L.) Sweet
hyacinth beans
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
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Winged Bean
Winged bean flowers and leaves
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Subfamily:Faboideae
Tribe:Phaseoleae
Genus:Psophocarpus
Species:P. tetragonolobus
Binomial name
Psophocarpus tetragonolobus
(L.) D.C.
Winged bean
Mucuna pruriens
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Subfamily:Faboideae
Tribe:Phaseoleae
Genus:Mucuna
Species:M. pruriens
Binomial name
Mucuna pruriens
(L.) DC.
Jicama
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Subfamily:Faboideae
Tribe:Phaseoleae
Genus:Pachyrhizus
Rich. ex DC.
Species
Pachyrhizus ahipa
Pachyrhizus erosus
Pachyrhizus ferrugineus
Pachyrhizus panamensis
Pachyrhizus tuberosus
e-- [email protected] Page 120 of 162
Winged Bean
Winged bean flowers and leaves
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Subfamily:Faboideae
Tribe:Phaseoleae
Genus:Psophocarpus
Species:P. tetragonolobus
Binomial name
Psophocarpus tetragonolobus
(L.) D.C.
Winged bean
Mucuna pruriens
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Subfamily:Faboideae
Tribe:Phaseoleae
Genus:Mucuna
Species:M. pruriens
Binomial name
Mucuna pruriens
(L.) DC.
Jicama
Scientific classification
Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Fabales
Family:Fabaceae
Subfamily:Faboideae
Tribe:Phaseoleae
Genus:Pachyrhizus
Rich. ex DC.
Species
Pachyrhizus ahipa
Pachyrhizus erosus
Pachyrhizus ferrugineus
Pachyrhizus panamensis
Pachyrhizus tuberosus
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 121 of 162
INTRODUCTION
Pulses are the edible fruits or seeds of pod bearing plants belonging to the family of
Leguminosae and are widely grown throughout the world. The term 'Legume' is derived from a Latin
word, legumen, meaning seeds harvested in pods. Alternative terms for the edible seeds include 'grain
legumes' and 'pulse'. In India, the term gram is commonly used for dry legumes seeds with husk, while
split decorticated grains are called 'dhal'. Some of the major pulses produced in India are
Common Name Botanical Name
1. Bengal Gram Cicer arietinum
2. Red Gram or Tur (Pigeon pea) Cajanus cajan
3. Black gram or Urad Phaseolus mungo
4. Green gram or Mung Phaseolus aureus
5. Lentil or Masur Lens culinaris
e-- [email protected] Page 121 of 162
INTRODUCTION
Pulses are the edible fruits or seeds of pod bearing plants belonging to the family of
Leguminosae and are widely grown throughout the world. The term 'Legume' is derived from a Latin
word, legumen, meaning seeds harvested in pods. Alternative terms for the edible seeds include 'grain
legumes' and 'pulse'. In India, the term gram is commonly used for dry legumes seeds with husk, while
split decorticated grains are called 'dhal'. Some of the major pulses produced in India are
Common Name Botanical Name
1. Bengal Gram Cicer arietinum
2. Red Gram or Tur (Pigeon pea) Cajanus cajan
3. Black gram or Urad Phaseolus mungo
4. Green gram or Mung Phaseolus aureus
5. Lentil or Masur Lens culinaris
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 122 of 162
6. Peas Pisum sativum
7. Khesari Dhal Lathyrus sativus
COMPOSITION
The chemical composition of edible pulses seeds depends upon the species. In general, their
protein content is high and is commonly more than twice that of cereal grains, usually constituting
about 20 per cent of the dry weight of seeds. The protein content of some legumes like soyabean is as
high as 40 per cent. They are also rich in carbohydrates and some species like groundnut and
soyabean are rich in oil.
Pulse Protein: Pulse proteins are chiefly globulins but albumins are also present. Pulse
proteins are deficient in sulphur containing amino acids, particularly in Methionine, and in
Tryptophan. But in soyabean tryptophan level is equal to FAO. All the pulses contain sufficient
amount of Leucine and Phenylalanine.
Carbohydrates: Food pulses contain about 55-60 per cent of total carbohydrates including
starch, soluble sugars, fibre and unavailable carbohydrates. This includes substantial level of
oligosaccharides of the raffinose family of sugars (reffinose, stachyose and verbiose), which are
notoriously known for the flatulence production in man and animals. These sugars escape digestion,
when they are ingested, due to the lack of α-glactosidase activity.
Lipids: Most dry beans possess relatively low total fat content generally 1-2 per cent.
Phospholipids make up 24-35 per cent while glycolipids account for upto 10 per cent of the total
lipid content of legume seeds. The fatty acid composition of legumes shown a significant amount of
variability; however, legume lipids are generally highly unsaturated 1-2 per cent with linolenic acid
present in the highest concentration.
Minerals: Important sources of Ca, Mg, Zn, Iron, K and P. A major portion (80%) of
phosphorus in many pulses is present as Phytate phosphorus.
Vitamins: Dry edible beans provide several water-soluble vitamins (thiamin, riboflavin,
nicotinic acid and folic acid) but very little ascorbic acid.
Grain Legume Processing
The question arises why grain legume processing is done. The main reason is food grain
legume utilization and common problems associated with the use of most legume seeds for food
include.
·Time and fuel energy required to prepare legume based food.
·Methionine deficiency in legume proteins.
·Presence of a variety of both heat stable and liable factors which interfere with digestion and
induce gastrointestinal distress and flatulence e.g. phytin complexes with proteins and
minerals and renders them biologically unavailable to human beings and animals.
Processing methods, such as cooking, soaking, germination, fermentation etc. can reduce or
eliminate amount of phytin.
So, the post harvest technology is done which involves the operations, which results in changes
desirable for mainly three reasons. These are
1)To improve the availability of nutrients in food.
2)To decrease the amount of antinutritive factors.
3)To increase the shelf life of material.
GRADING, HANDLING AND STORAGE
Most grains are harvested after a period of field drying, when pods and grains are exposed to
attack by birds, rodents and insects.
e-- [email protected] Page 122 of 162
6. Peas Pisum sativum
7. Khesari Dhal Lathyrus sativus
COMPOSITION
The chemical composition of edible pulses seeds depends upon the species. In general, their
protein content is high and is commonly more than twice that of cereal grains, usually constituting
about 20 per cent of the dry weight of seeds. The protein content of some legumes like soyabean is as
high as 40 per cent. They are also rich in carbohydrates and some species like groundnut and
soyabean are rich in oil.
Pulse Protein: Pulse proteins are chiefly globulins but albumins are also present. Pulse
proteins are deficient in sulphur containing amino acids, particularly in Methionine, and in
Tryptophan. But in soyabean tryptophan level is equal to FAO. All the pulses contain sufficient
amount of Leucine and Phenylalanine.
Carbohydrates: Food pulses contain about 55-60 per cent of total carbohydrates including
starch, soluble sugars, fibre and unavailable carbohydrates. This includes substantial level of
oligosaccharides of the raffinose family of sugars (reffinose, stachyose and verbiose), which are
notoriously known for the flatulence production in man and animals. These sugars escape digestion,
when they are ingested, due to the lack of α-glactosidase activity.
Lipids: Most dry beans possess relatively low total fat content generally 1-2 per cent.
Phospholipids make up 24-35 per cent while glycolipids account for upto 10 per cent of the total
lipid content of legume seeds. The fatty acid composition of legumes shown a significant amount of
variability; however, legume lipids are generally highly unsaturated 1-2 per cent with linolenic acid
present in the highest concentration.
Minerals: Important sources of Ca, Mg, Zn, Iron, K and P. A major portion (80%) of
phosphorus in many pulses is present as Phytate phosphorus.
Vitamins: Dry edible beans provide several water-soluble vitamins (thiamin, riboflavin,
nicotinic acid and folic acid) but very little ascorbic acid.
Grain Legume Processing
The question arises why grain legume processing is done. The main reason is food grain
legume utilization and common problems associated with the use of most legume seeds for food
include.
·Time and fuel energy required to prepare legume based food.
·Methionine deficiency in legume proteins.
·Presence of a variety of both heat stable and liable factors which interfere with digestion and
induce gastrointestinal distress and flatulence e.g. phytin complexes with proteins and
minerals and renders them biologically unavailable to human beings and animals.
Processing methods, such as cooking, soaking, germination, fermentation etc. can reduce or
eliminate amount of phytin.
So, the post harvest technology is done which involves the operations, which results in changes
desirable for mainly three reasons. These are
1)To improve the availability of nutrients in food.
2)To decrease the amount of antinutritive factors.
3)To increase the shelf life of material.
GRADING, HANDLING AND STORAGE
Most grains are harvested after a period of field drying, when pods and grains are exposed to
attack by birds, rodents and insects.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 123 of 162
Insect Damage: Pulses undergo substantial quantitative and qualitative losses during post
harvest handling, storage and distribution and result in rodent and insect infestation and infection by
fungi. These losses may be as high as 70 per cent legumes attacked by pulse beetle (Callosobruchus
chinensis) are rendered unfit for human consumption. Besides the presence of excreta, the grains are
contaminated with metabolites such as uric acid. Rancidity goes up and secondary infection takes
place due to fungi.
Recent studies have shown that insect infestation significantly decreased the protein efficiency
ratio of chickpea and pigeonpea.
The best method to present insect losses is to store, the grain in sealed containers after
thorough drying in the hot sun. The phostoxin fumigation tablet is highly effective against insects,
both in bulk as well as small-scale storage.
Effect of insect infestation on the yield dhal from chickpea
% Kernel damage % dal yield
Chickpea (uninfested) 2 82
Chickpea (infested by insects) 15 65
Seeds are graded according to the amount of broken, unripe, shriveled, infested, dented, pitted,
off coloured and moldy grains present.
PROCESSING
Processing of pulses of primary importance in improving their nutritive value.
Soaking: Soaking in water is the first step of preparing pulses for consumption. It is done by
sinking/drowning the pulses in water to reduce the oligosaccharide content of the raffinose family.
Soaking also reduces the amount of phytic acid in pulses. No loss of nutrients occurs when
the grains are soaked in their skins, and the soaking water is not warmed. Putting the legumes into
boiling water to produce more rapid softening may, however, lead to diffusion into the water of some
25 per cent of the thiamine originally present. Presumably other water-soluble nutrients will diffuse
into the water to about the same extent. The practice of using boiling water for soaking is uncommon
in most parts of the world.
Platt has commented, “The soaking process constitutes a first stage in germination and is a process the
importance of which, for human food has in my view been neglected”. It is conceivable that the
constituents of the seed stored in an almost inert form begin to be organized during soaking for supply
to the embryo, and equally they may become more assimilable when eaten as human food. How far
such changes take place depends on the duration of soaking; probably they will not occur to any extent
when the soaking period is 12 hours or less.
Traditionally dry beans have been soaked overnight (8-16 hr) in cold water. High
temperature soaking accelerates hydration. The degree and rate of hydration of the starch
protein matrix influences the cooking rate and final texture.
Drying
The drying Procedure is generally employed
a) To prevent germination, of seeds
b) To retain maximum quality of grain
c) To reach a level of moisture that doesn't allow the growth of bacteria and fungi and
considerably retards infestation by mites and insects.
They are two types of drying
e-- [email protected] Page 123 of 162
Insect Damage: Pulses undergo substantial quantitative and qualitative losses during post
harvest handling, storage and distribution and result in rodent and insect infestation and infection by
fungi. These losses may be as high as 70 per cent legumes attacked by pulse beetle (Callosobruchus
chinensis) are rendered unfit for human consumption. Besides the presence of excreta, the grains are
contaminated with metabolites such as uric acid. Rancidity goes up and secondary infection takes
place due to fungi.
Recent studies have shown that insect infestation significantly decreased the protein efficiency
ratio of chickpea and pigeonpea.
The best method to present insect losses is to store, the grain in sealed containers after
thorough drying in the hot sun. The phostoxin fumigation tablet is highly effective against insects,
both in bulk as well as small-scale storage.
Effect of insect infestation on the yield dhal from chickpea
% Kernel damage % dal yield
Chickpea (uninfested) 2 82
Chickpea (infested by insects) 15 65
Seeds are graded according to the amount of broken, unripe, shriveled, infested, dented, pitted,
off coloured and moldy grains present.
PROCESSING
Processing of pulses of primary importance in improving their nutritive value.
Soaking: Soaking in water is the first step of preparing pulses for consumption. It is done by
sinking/drowning the pulses in water to reduce the oligosaccharide content of the raffinose family.
Soaking also reduces the amount of phytic acid in pulses. No loss of nutrients occurs when
the grains are soaked in their skins, and the soaking water is not warmed. Putting the legumes into
boiling water to produce more rapid softening may, however, lead to diffusion into the water of some
25 per cent of the thiamine originally present. Presumably other water-soluble nutrients will diffuse
into the water to about the same extent. The practice of using boiling water for soaking is uncommon
in most parts of the world.
Platt has commented, “The soaking process constitutes a first stage in germination and is a process the
importance of which, for human food has in my view been neglected”. It is conceivable that the
constituents of the seed stored in an almost inert form begin to be organized during soaking for supply
to the embryo, and equally they may become more assimilable when eaten as human food. How far
such changes take place depends on the duration of soaking; probably they will not occur to any extent
when the soaking period is 12 hours or less.
Traditionally dry beans have been soaked overnight (8-16 hr) in cold water. High
temperature soaking accelerates hydration. The degree and rate of hydration of the starch
protein matrix influences the cooking rate and final texture.
Drying
The drying Procedure is generally employed
a) To prevent germination, of seeds
b) To retain maximum quality of grain
c) To reach a level of moisture that doesn't allow the growth of bacteria and fungi and
considerably retards infestation by mites and insects.
They are two types of drying
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 124 of 162
1) Sun drying
In the tropics, sun drying is the common method of drying. With sun drying, grains are spread
on the threshing yard for 2-3 days and once dried, are transferred to storage. Sun drying requires
frequent turning of the layer of drying grains. This method is not suitable for large quantities of grains
and under humid and cloudy weather conditions. Mostly all pulses are sundried.
2) Mechanical drying
This is industrial method used before dehulling. In most developed countries drying of legume
grains is carried out with mechanical driers. Continuous batch driers or in bin driers are commonly
used. Various mechanical driers such as low-temperature driers, tray driers, radical flow driers,
multiduct ventilated flow driers, in-bin driers, on the floor dries and solar driers are used for drying.
The seeds of legumes should be dried immediately following threshing. The drying temperature for
various legumes being harvested for different end uses has been reported. If high moisture grains are
heated at high temperature, the outer layers become hard. The grains will appear to be properly dried,
but the inside will, be soft and wet and the passage of moisture from center to periphery will take
some time,
Excessive heat applied to wet beans can split the seeds. For large beans, two-stage drying is
often recommended to ensure satisfactory moisture reduction and to keep seed unaffected. Beans
should be dried to 15 per cent moisture and peanuts and soyabeans should be dried to 8 and 11 per
cent moisture respectively for safe storage.
Maximum air temperature for drying of various legumes
Commodity Maximum air temperature (ºC)
Beans-seeds 38
Beans-animal feed 45
Cowpeas-seed 38
Soybeans-seed 38
Soybeans-manufacture 48
Groundnut (peanut) seed 37
The most suitable drying system is one utilizing air at ambient temperature. The use of ambient
temperature air (or air heated only slightly above ambient temperature) is practiced in many countries
to aerate grains. This is done to
a) Lower grain temperature
b) To equalize grain temperature through the bulk
c) Remove unpleasant odors or toxic gases after fumigation
d) Reduce moisture content by a very small amount
Dehulling of Pulses
Dehulling process, also called primary processing converts the whole seed of pulses into dhal
(decorticated dry split cotyledons) that is important operation of post-harvest handling of pulses. It is
estimated that over 75 per cent of chickpea and 85 per cent of pigeonpea produced in India are
dehulled to produce dhal.
Production of pulses will depend on the methods and machinery used for dehulling, several
factors such as environmental, agronomic practices, genotypes and pre-treatments influence the
dehulling process.
e-- [email protected] Page 124 of 162
1) Sun drying
In the tropics, sun drying is the common method of drying. With sun drying, grains are spread
on the threshing yard for 2-3 days and once dried, are transferred to storage. Sun drying requires
frequent turning of the layer of drying grains. This method is not suitable for large quantities of grains
and under humid and cloudy weather conditions. Mostly all pulses are sundried.
2) Mechanical drying
This is industrial method used before dehulling. In most developed countries drying of legume
grains is carried out with mechanical driers. Continuous batch driers or in bin driers are commonly
used. Various mechanical driers such as low-temperature driers, tray driers, radical flow driers,
multiduct ventilated flow driers, in-bin driers, on the floor dries and solar driers are used for drying.
The seeds of legumes should be dried immediately following threshing. The drying temperature for
various legumes being harvested for different end uses has been reported. If high moisture grains are
heated at high temperature, the outer layers become hard. The grains will appear to be properly dried,
but the inside will, be soft and wet and the passage of moisture from center to periphery will take
some time,
Excessive heat applied to wet beans can split the seeds. For large beans, two-stage drying is
often recommended to ensure satisfactory moisture reduction and to keep seed unaffected. Beans
should be dried to 15 per cent moisture and peanuts and soyabeans should be dried to 8 and 11 per
cent moisture respectively for safe storage.
Maximum air temperature for drying of various legumes
Commodity Maximum air temperature (ºC)
Beans-seeds 38
Beans-animal feed 45
Cowpeas-seed 38
Soybeans-seed 38
Soybeans-manufacture 48
Groundnut (peanut) seed 37
The most suitable drying system is one utilizing air at ambient temperature. The use of ambient
temperature air (or air heated only slightly above ambient temperature) is practiced in many countries
to aerate grains. This is done to
a) Lower grain temperature
b) To equalize grain temperature through the bulk
c) Remove unpleasant odors or toxic gases after fumigation
d) Reduce moisture content by a very small amount
Dehulling of Pulses
Dehulling process, also called primary processing converts the whole seed of pulses into dhal
(decorticated dry split cotyledons) that is important operation of post-harvest handling of pulses. It is
estimated that over 75 per cent of chickpea and 85 per cent of pigeonpea produced in India are
dehulled to produce dhal.
Production of pulses will depend on the methods and machinery used for dehulling, several
factors such as environmental, agronomic practices, genotypes and pre-treatments influence the
dehulling process.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 125 of 162
Advantages of Dehulling
1) Reduction of cooking time in terms of removing the impermeable seed coat, which hinder water
uptake during cooking.
2) Improve their palatability and taste, as the seed coat is indigestible and causes a bitter taste.
3) Reducing of anti-nutritional factors present in the seed coat as polyphenols also called as tannins
and phytates
4) Improves the protein quality in pulses.
5) Removal of hull facilitates reduction of fibre.
6) Improvement in the appearance, texture, cooking quality, palatability and digestibility.
Methods of Dehulling
The conversion of pulses into dhal is an age-old method. Both small and large-scale industries
have evolved to some extent from this traditional food processing method. The dehulling methods can
be broadly classified into two categories.
1) TRADITIONAL METHOD
a) Small scale processing generally adopted by the households and -villages.
b) Large scale processing adopted by the commercial dhal mills in urban areas.
2. MODERN METHODS
a) Laboratory dehullers
b) Mini dhal mills.
Traditional method
Small-scale process: In the early days, dehulling of pulses was accomplished traditionally
with a mortar and pestle and stone chakki is used. The pre-treatments given before dehulling in-a
chakki vary from region to region.
Large Scale Processing: In commercial dhal mills, energy-coated rollers are used. The energy
coating, also called as, carborundum, is made of silicon carbide (carbon + crystallized alumina) and
used for abrasive or refractory action. Some millers use a roller for both dehusking and husking while
others use a roller and disc shelter alternatively for this purpose. The disc shelter is generally used for
wet processing.
Processing of Chickpea
1) Foreign material is first removed by sieving and exposure to fans. This removes soil. straw, pods,
weeds etc.
2) Seed material is graded into different sizes depending on the species.
3) Seed lots are passed through a roller machine, which causes a mild abrasion - the tempering
operation which causes scratches on the seed coat, testa and enhances their oil and water absorbing
efficiency.
4)The material is then treated with oil and water and processed.
e-- [email protected] Page 125 of 162
Advantages of Dehulling
1) Reduction of cooking time in terms of removing the impermeable seed coat, which hinder water
uptake during cooking.
2) Improve their palatability and taste, as the seed coat is indigestible and causes a bitter taste.
3) Reducing of anti-nutritional factors present in the seed coat as polyphenols also called as tannins
and phytates
4) Improves the protein quality in pulses.
5) Removal of hull facilitates reduction of fibre.
6) Improvement in the appearance, texture, cooking quality, palatability and digestibility.
Methods of Dehulling
The conversion of pulses into dhal is an age-old method. Both small and large-scale industries
have evolved to some extent from this traditional food processing method. The dehulling methods can
be broadly classified into two categories.
1) TRADITIONAL METHOD
a) Small scale processing generally adopted by the households and -villages.
b) Large scale processing adopted by the commercial dhal mills in urban areas.
2. MODERN METHODS
a) Laboratory dehullers
b) Mini dhal mills.
Traditional method
Small-scale process: In the early days, dehulling of pulses was accomplished traditionally
with a mortar and pestle and stone chakki is used. The pre-treatments given before dehulling in-a
chakki vary from region to region.
Large Scale Processing: In commercial dhal mills, energy-coated rollers are used. The energy
coating, also called as, carborundum, is made of silicon carbide (carbon + crystallized alumina) and
used for abrasive or refractory action. Some millers use a roller for both dehusking and husking while
others use a roller and disc shelter alternatively for this purpose. The disc shelter is generally used for
wet processing.
Processing of Chickpea
1) Foreign material is first removed by sieving and exposure to fans. This removes soil. straw, pods,
weeds etc.
2) Seed material is graded into different sizes depending on the species.
3) Seed lots are passed through a roller machine, which causes a mild abrasion - the tempering
operation which causes scratches on the seed coat, testa and enhances their oil and water absorbing
efficiency.
4)The material is then treated with oil and water and processed.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 126 of 162
Seed Material
Cleaning
Grading
Tempering Operation
Oil/ Water Treatment
Sun Drying
Dehulling
Method 1
(AP & Maharashtra)
Seed Material
Cleaning
Tempering
Oil & Turmeric Powder
Treatment
Store
(30-45 Days)
Dehulling in Stone Chakki
(Removes Seed Coat)
Dhal
Method 2
(Maharashtra & MP)
Seed Material
Cleaning
Soaking in Water
(8-14 hrs)
Sun Drying
(1 or 2 Days)
Primary Milling
(Cotyledons Seperate)
Oil/ Water Treatment
Sun Drying
(1 or 2 Days)
Dehulling in Stone Chakki
(Removes Seed Coat)
Dhal
Method 3
(UP & MP)
Seed Material
Cleaning
Boiling in Water
(15-20 min)
Sun Drying
(1 or 2 Days)
Dehulling in Stone Chakki
(Removes Seed Coat)
Dhal
Very Small and Damaged/
immature seeds (discarded or
used as animal feed)
Dirt/ Dust/ Mud Balls
Average Uniform Seed Size
Very Bold
(Discarded or Dehulled separately
depending upon the quantity)
Unhusked
(Whole
Seed)
Dhal,
Brokens,
Powder,
Husk
e-- [email protected] Page 126 of 162
Seed Material
Cleaning
Grading
Tempering Operation
Oil/ Water Treatment
Sun Drying
Dehulling
Method 1
(AP & Maharashtra)
Seed Material
Cleaning
Tempering
Oil & Turmeric Powder
Treatment
Store
(30-45 Days)
Dehulling in Stone Chakki
(Removes Seed Coat)
Dhal
Method 2
(Maharashtra & MP)
Seed Material
Cleaning
Soaking in Water
(8-14 hrs)
Sun Drying
(1 or 2 Days)
Primary Milling
(Cotyledons Seperate)
Oil/ Water Treatment
Sun Drying
(1 or 2 Days)
Dehulling in Stone Chakki
(Removes Seed Coat)
Dhal
Method 3
(UP & MP)
Seed Material
Cleaning
Boiling in Water
(15-20 min)
Sun Drying
(1 or 2 Days)
Dehulling in Stone Chakki
(Removes Seed Coat)
Dhal
Very Small and Damaged/
immature seeds (discarded or
used as animal feed)
Dirt/ Dust/ Mud Balls
Average Uniform Seed Size
Very Bold
(Discarded or Dehulled separately
depending upon the quantity)
Unhusked
(Whole
Seed)
Dhal,
Brokens,
Powder,
Husk
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 127 of 162
Unsplit Dehulled
Water Treatment
Sun Drying
Splitting
Dhal
Pigeon Pea dehulling procedure followed in Indian Dhal Mills
Seed Material
Cleaning
Grading
Uniform Seed Size Lot
Mild Tempering
Water Treatment
Sun Drying
Dehulling
Unsplit Dehulled
Water Treatment
Sun Drying
Splitting
Dhal
Chick Pea dehulling procedure followed in Indian Dhal Mills
Dehulling Pre-treatments
In both small scale and large scale processing of pulses, two major operations are involved
a) Loosening the seed coat from cotyledons,
b) Removing the seed coat and splitting the cotyledons.
The pre-treatments are generally employed to loosen the seed coats and these can be grouped
into two categories
a)Wet-treatment
b)Dry treatment
WET TREATMENT
This involves water soaking and sun drying which is considered as effective technique to
loosen the husk. This method facilitates good dehusking and splitting and giving less breakage.
Disadvantage
Adversely affect cooking quality and also it is lab our Intensive. It is completely dependent
upon climatic condition for drying.
Very Small and Damaged/
immature seeds (discarded or
used as animal feed) Dirt/ Dust/ Mud Balls (Discarded)
Very Large
(Discarded or Dehulled separately
depending upon the quantity)
Unhusked
(Whole
Seed)
Dhal,
Brokens,
Powder,
Husk
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Unsplit Dehulled
Water Treatment
Sun Drying
Splitting
Dhal
Pigeon Pea dehulling procedure followed in Indian Dhal Mills
Seed Material
Cleaning
Grading
Uniform Seed Size Lot
Mild Tempering
Water Treatment
Sun Drying
Dehulling
Unsplit Dehulled
Water Treatment
Sun Drying
Splitting
Dhal
Chick Pea dehulling procedure followed in Indian Dhal Mills
Dehulling Pre-treatments
In both small scale and large scale processing of pulses, two major operations are involved
a) Loosening the seed coat from cotyledons,
b) Removing the seed coat and splitting the cotyledons.
The pre-treatments are generally employed to loosen the seed coats and these can be grouped
into two categories
a)Wet-treatment
b)Dry treatment
WET TREATMENT
This involves water soaking and sun drying which is considered as effective technique to
loosen the husk. This method facilitates good dehusking and splitting and giving less breakage.
Disadvantage
Adversely affect cooking quality and also it is lab our Intensive. It is completely dependent
upon climatic condition for drying.
Very Small and Damaged/
immature seeds (discarded or
used as animal feed) Dirt/ Dust/ Mud Balls (Discarded)
Very Large
(Discarded or Dehulled separately
depending upon the quantity)
Unhusked
(Whole
Seed)
Dhal,
Brokens,
Powder,
Husk
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 128 of 162
It takes 5-6 days. Soaking in water, followed by coating with red earth slurry and sun drying
for several hours is a household practice for dehulling pigeonpea. This imparts a good yellow colour to
the finished product, possibly by preserving its natural colour.
Chemical treatment
Sodium bicarbonate (5% solution) is used which increases dhal yield. It loosens the husk and
also reduces the cooking time.
Disadvantage
Vitamin loss is significant.
Dry treatment
This method is more applicable for chickpea dehulling and pigeonpea. The major disadvantage
of the dry method is the high dehulling losses due to breakage and powdering.
Oil treatment
After tempering operation, grains are thoroughly mixed with about 1 per cent oil (preferably
linseed, either manually or in a worm mixer and then dried in sun for 2-3 days. Oil appears to
penetrate through the husk to the cotyledons and releases it’s binding under the mild heat of the sun.
The loosening process may be slow, but the husk is totally loosened. Oil and turmeric powder as a pre-
treatment are also given.
Heat treatment
Hot air at 120-180ºC was quite effective in loosening the seed coat.
Effect of dehulling on nutrient losses
Most common methods of dehulling of legumes remove the germ along with the husk and
thereby incur losses of vitamins and proteins. As the dehulling time increases- protein, calcium and
iron contents of dhal decrease.
Effect of dehulling on cooking time of dhals
Dehulling method influences the cooking time of dhals of pulses. Soaking the seeds in water
and subsequent sun or oven drying increases the cooking time in grain legumes. If soaking in 1
percent solution of sodium carbonate decreased it considerably.
e-- [email protected] Page 128 of 162
It takes 5-6 days. Soaking in water, followed by coating with red earth slurry and sun drying
for several hours is a household practice for dehulling pigeonpea. This imparts a good yellow colour to
the finished product, possibly by preserving its natural colour.
Chemical treatment
Sodium bicarbonate (5% solution) is used which increases dhal yield. It loosens the husk and
also reduces the cooking time.
Disadvantage
Vitamin loss is significant.
Dry treatment
This method is more applicable for chickpea dehulling and pigeonpea. The major disadvantage
of the dry method is the high dehulling losses due to breakage and powdering.
Oil treatment
After tempering operation, grains are thoroughly mixed with about 1 per cent oil (preferably
linseed, either manually or in a worm mixer and then dried in sun for 2-3 days. Oil appears to
penetrate through the husk to the cotyledons and releases it’s binding under the mild heat of the sun.
The loosening process may be slow, but the husk is totally loosened. Oil and turmeric powder as a pre-
treatment are also given.
Heat treatment
Hot air at 120-180ºC was quite effective in loosening the seed coat.
Effect of dehulling on nutrient losses
Most common methods of dehulling of legumes remove the germ along with the husk and
thereby incur losses of vitamins and proteins. As the dehulling time increases- protein, calcium and
iron contents of dhal decrease.
Effect of dehulling on cooking time of dhals
Dehulling method influences the cooking time of dhals of pulses. Soaking the seeds in water
and subsequent sun or oven drying increases the cooking time in grain legumes. If soaking in 1
percent solution of sodium carbonate decreased it considerably.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 129 of 162
Dry milling of black gram
1. After cleaning, the black grams are subjected to pricking in a rough roller mill for some scratching
as well as partial removal of the waxy coating on the black grams.
2. The scratched grains are then coated with 1 to 2% oil in a worm mixer and the heaped over night for
diffusion of the oil in the grains.
3. The scratched and oil coated pulses are sprayed in drying yards for sun drying for 4 to 6 hours.
4. The partially dried grains are moistened with a spray of 4-5% water and kept overnight.
5. The wetted pulses are then dried for 3-4 days in the sun.
6. The thoroughly dried pulses are dehusked in a roller. About 40-50% pulses are dehusked in first
milling operation.
7. The husk and powder are then aspirated off.
8. Then the split 'dhal' is separated from dehusked whole dhal and unhusked pulses by sieving.
The average yield of 'dhal' is 70-71 per cent.
Dry milling of green gram
In dry milling of green gram, both oil and water treatments are given to the grains. The wetted
grains are dried in the sun. Then the dried pulses are simultaneously dehusked and split using a
dehusking machine. After removal of husk split dhal is separated from the mixture as usual. The yield
of dhal is poor which varies from 62 to 65 per cent only.
MODERN CFTRI METHOD OF PULSE MILLING
1) Cleaning
Cleaning is done in rotary reel cleaners to remove all impurities from pulses and separate them
according to size.
2) Preconditioning
The cleaned pulses are conditioned in two passes in a dryer using hot air at about 120ºC for a
certain period of time. After each pass, the hot pulses are tempered in the tempering bins for about six
hours. The preconditioning of pulses helps in loosening husk significantly.
3) Dehusking
The preconditioned are conveyed to the pearler or dehusker where almost all pulses are
dehusked in a single operation. The dehusked whole pulses (gota) are separated from split pulses and
mixture of husk, brokens etc. and are received in a screw conveyor where water is added at a
controlled rate. The moistened gota is then collected on the floor and allowed to remain as such for
about an hour.
4) Lump breaking
Some of the moistened gota form into lumps of various sizes. These lumps are fed to the lump
breaker to break them.
5) Conditioning and splitting
After lump breaking the gota is conveyed to dryer where it is exposed to hot air for a few
hours. The gota is thus dried to the proper moisture level for splitting. The hot conditioned and dried
dehusked whole pulses are split in the emery roller. All of them are not split in one pass. The mixture
e-- [email protected] Page 129 of 162
Dry milling of black gram
1. After cleaning, the black grams are subjected to pricking in a rough roller mill for some scratching
as well as partial removal of the waxy coating on the black grams.
2. The scratched grains are then coated with 1 to 2% oil in a worm mixer and the heaped over night for
diffusion of the oil in the grains.
3. The scratched and oil coated pulses are sprayed in drying yards for sun drying for 4 to 6 hours.
4. The partially dried grains are moistened with a spray of 4-5% water and kept overnight.
5. The wetted pulses are then dried for 3-4 days in the sun.
6. The thoroughly dried pulses are dehusked in a roller. About 40-50% pulses are dehusked in first
milling operation.
7. The husk and powder are then aspirated off.
8. Then the split 'dhal' is separated from dehusked whole dhal and unhusked pulses by sieving.
The average yield of 'dhal' is 70-71 per cent.
Dry milling of green gram
In dry milling of green gram, both oil and water treatments are given to the grains. The wetted
grains are dried in the sun. Then the dried pulses are simultaneously dehusked and split using a
dehusking machine. After removal of husk split dhal is separated from the mixture as usual. The yield
of dhal is poor which varies from 62 to 65 per cent only.
MODERN CFTRI METHOD OF PULSE MILLING
1) Cleaning
Cleaning is done in rotary reel cleaners to remove all impurities from pulses and separate them
according to size.
2) Preconditioning
The cleaned pulses are conditioned in two passes in a dryer using hot air at about 120ºC for a
certain period of time. After each pass, the hot pulses are tempered in the tempering bins for about six
hours. The preconditioning of pulses helps in loosening husk significantly.
3) Dehusking
The preconditioned are conveyed to the pearler or dehusker where almost all pulses are
dehusked in a single operation. The dehusked whole pulses (gota) are separated from split pulses and
mixture of husk, brokens etc. and are received in a screw conveyor where water is added at a
controlled rate. The moistened gota is then collected on the floor and allowed to remain as such for
about an hour.
4) Lump breaking
Some of the moistened gota form into lumps of various sizes. These lumps are fed to the lump
breaker to break them.
5) Conditioning and splitting
After lump breaking the gota is conveyed to dryer where it is exposed to hot air for a few
hours. The gota is thus dried to the proper moisture level for splitting. The hot conditioned and dried
dehusked whole pulses are split in the emery roller. All of them are not split in one pass. The mixture
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 130 of 162
is graded into grade 1 pulses, dehusked whole pulses and small brokens. The unsplit dehusked pulses
are again fed to the conditioner for subsequent splitting.
GERMINATION/SPROUTING
Soaking legume seeds and holding at ambient temperature will facilitate germination.
Germination has profound effects on the physico-chemical compositional changes in dry beans and
improves the nutritional quality of legumes.
In sprouting the higher the temperature, the faster the sprout grows. But temperature higher
than 27ºC favors the mould growth. So good temperature for sprouting is 22-24ºC, generally for all
pulses, which are put out of direct sunlight. Germination improves the nutritive value of food pulses.
·The ascorbic acid content of pulses increases manifold after 48 hrs germination.
·The riboflavin, niacin, choline and biotin contents of all pulses increases during germination.
·The folic acid content greatly decreases.
·Pantothenic acid value remains practically unchanged.
·Changes in the carbohydrate of pulses, some of the starch being converted into sugars.
·It reduces or eliminates most of the antinutritional and toxic factors several pulses.
·Protein content increases.
Uses
·Germinated or sprouted pulses are used to cure scurvy.
·Used either as salad or vegetable.
·Used in infant food preparations.
FERMENTATION
Raw Pulses
Cleaning and Grading
First Conditioning & Tempering
Second Conditioning & Tempering
Dhal
Pearled Pulses
Conditioning in LSU type Aerator
Conditioned Pulses
Splitting and Sieve Grading
Dhal
(Grade 1)
Milling of Tur by CFTRI Method
Husk
Pearling, aspirating
and Grading
Polishing Dhal (Grade2)
Water Mixing Lumped Pulses Lump Breaking
Unsplit Pulses
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is graded into grade 1 pulses, dehusked whole pulses and small brokens. The unsplit dehusked pulses
are again fed to the conditioner for subsequent splitting.
GERMINATION/SPROUTING
Soaking legume seeds and holding at ambient temperature will facilitate germination.
Germination has profound effects on the physico-chemical compositional changes in dry beans and
improves the nutritional quality of legumes.
In sprouting the higher the temperature, the faster the sprout grows. But temperature higher
than 27ºC favors the mould growth. So good temperature for sprouting is 22-24ºC, generally for all
pulses, which are put out of direct sunlight. Germination improves the nutritive value of food pulses.
·The ascorbic acid content of pulses increases manifold after 48 hrs germination.
·The riboflavin, niacin, choline and biotin contents of all pulses increases during germination.
·The folic acid content greatly decreases.
·Pantothenic acid value remains practically unchanged.
·Changes in the carbohydrate of pulses, some of the starch being converted into sugars.
·It reduces or eliminates most of the antinutritional and toxic factors several pulses.
·Protein content increases.
Uses
·Germinated or sprouted pulses are used to cure scurvy.
·Used either as salad or vegetable.
·Used in infant food preparations.
FERMENTATION
Raw Pulses
Cleaning and Grading
First Conditioning & Tempering
Second Conditioning & Tempering
Dhal
Pearled Pulses
Conditioning in LSU type Aerator
Conditioned Pulses
Splitting and Sieve Grading
Dhal
(Grade 1)
Milling of Tur by CFTRI Method
Husk
Pearling, aspirating
and Grading
Polishing Dhal (Grade2)
Water Mixing Lumped Pulses Lump Breaking
Unsplit Pulses
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 131 of 162
It reduces oligosaccharide content of pulses that is responsible for flatulence. Soyabean is a
very valuable pulse whose protein approaches the quality of animal protein. However, it cannot be
directly used as a food because of the toxic substances present in the pulse. The toxic substances can
be eliminated by fermentation.
Fermented products of soyabean
1) Soya Sauce
Soyabean are cooked for 4 to 6 hours and cooled. They are then mixed with an equal quantity
of roasted ground wheat and the mixture, under suitable conditions, is seeded with Aspergillus oryzae.
After the initial fermentation, salt is added and the product is matured for 6 months to 3 years when
further fermentation occurs. When 'ripening' is complete, the product is strained. Soya sauce thus
obtained contains 67 per cent moisture and 5 to 6 per cent protein.
Washed and soaked overnight in tap water
Steamed or boiled
Drained and cooled
Inoculated____________Bacillus subtilis
Mixed and packaged in small packages
Incubated at 40-43ºC for 12-20 hrs
Soyabean Oil Processing
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It reduces oligosaccharide content of pulses that is responsible for flatulence. Soyabean is a
very valuable pulse whose protein approaches the quality of animal protein. However, it cannot be
directly used as a food because of the toxic substances present in the pulse. The toxic substances can
be eliminated by fermentation.
Fermented products of soyabean
1) Soya Sauce
Soyabean are cooked for 4 to 6 hours and cooled. They are then mixed with an equal quantity
of roasted ground wheat and the mixture, under suitable conditions, is seeded with Aspergillus oryzae.
After the initial fermentation, salt is added and the product is matured for 6 months to 3 years when
further fermentation occurs. When 'ripening' is complete, the product is strained. Soya sauce thus
obtained contains 67 per cent moisture and 5 to 6 per cent protein.
Washed and soaked overnight in tap water
Steamed or boiled
Drained and cooled
Inoculated____________Bacillus subtilis
Mixed and packaged in small packages
Incubated at 40-43ºC for 12-20 hrs
Soyabean Oil Processing
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 132 of 162
Soybean Extraction Process
2) Idli
Degummed
Oil
Crude
Soyabean Oil
Alkali refined
Oil
Partially
Hydrogenated
Oil
Bleached Oil
Blended Oil
Margarine
Stock
Deodorization
Margarine
Water
Alkali
Activated Earth
H
2
Catalyst
Lecithin
Sludge
Soap
Stock
Salad Oil
Salad Oil
Salad Dressing
Cooling Oil
Other Fatty Oil
Shortening Stock
Shortening Mellorine
Fat Specialities
Votator
Votator
Winterization and
Deodorization
Salad and Cppking Oil
Liquid Shortening
Monoglycerides and
Tristearin
Soybean Storage
Surge Bin
Conditioner (Conditioned to 9.5 to 10% moisture, 74-79º C)
Flaking Mill (Flakes of 0.025mm
thickness)
Meal Cooler
Meal Grinder
Meal Screen
Raw Flake
Elevator
Extractor Feed Conveyor (Percolation type Hexane Solvent
Stationary Basket Extractor
Spent Flake Elevator (Contain 35% Hexane, 7-8% Water, 0.5-1% Oil)
Desolventizer Toaster (Hexane is removed using
Steam)
Vapor Scrubber
1
st
Stage
Evaporator
1
st
Stage Condenser (Contains 65-78%
oil)
2
nd
Stage Evaporator
2
nd
Stage Condenser (Contains 90-95%
oil)
Final Oil Stripper
Vacuum
Condenser
Steam Jacketed Cooker
Smooth Surface Rolls
e-- [email protected] Page 132 of 162
Soybean Extraction Process
2) Idli
Degummed
Oil
Crude
Soyabean Oil
Alkali refined
Oil
Partially
Hydrogenated
Oil
Bleached Oil
Blended Oil
Margarine
Stock
Deodorization
Margarine
Water
Alkali
Activated Earth
H
2
Catalyst
Lecithin
Sludge
Soap
Stock
Salad Oil
Salad Oil
Salad Dressing
Cooling Oil
Other Fatty Oil
Shortening Stock
Shortening Mellorine
Fat Specialities
Votator
Votator
Winterization and
Deodorization
Salad and Cppking Oil
Liquid Shortening
Monoglycerides and
Tristearin
Soybean Storage
Surge Bin
Conditioner (Conditioned to 9.5 to 10% moisture, 74-79º C)
Flaking Mill (Flakes of 0.025mm
thickness)
Meal Cooler
Meal Grinder
Meal Screen
Raw Flake
Elevator
Extractor Feed Conveyor (Percolation type Hexane Solvent
Stationary Basket Extractor
Spent Flake Elevator (Contain 35% Hexane, 7-8% Water, 0.5-1% Oil)
Desolventizer Toaster (Hexane is removed using
Steam)
Vapor Scrubber
1
st
Stage
Evaporator
1
st
Stage Condenser (Contains 65-78%
oil)
2
nd
Stage Evaporator
2
nd
Stage Condenser (Contains 90-95%
oil)
Final Oil Stripper
Vacuum
Condenser
Steam Jacketed Cooker
Smooth Surface Rolls
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 133 of 162
A mungo bean-based product, Idli, made from mungo beans and rice is popular in southern
India. Idli is prepared by washing, soaking and grinding rice and mungo beans, followed by mixing.
The proportions of rice to beans varied from 4 parts beans: 1 part rice to 1 part beans: 4 parts rice. The
mix is allowed to ferment overnight. No inoculum is needed because the naturally present flora is
sufficient to carryout the fermentation. Leuconostoc mesenteroides is the predominant microorganism
and Streptococcus faecalis and Pediococcus are also present. The fermented idli is steamed and served
hot.
3) Soya bean paste (miso)
Soyabean paste is mostly a Japanese product. The fermenting agent, as in soya sauce, is
Aspergillus oryzae. The ingredients are cooked soyabean and steamed rice or barley, and the mixture
is fermented from 2 weeks to years. The rate of fermentation is controlled by the addition of salt.
It is used in the preparation of soups or served with rice and other foods as dressings or a side dish.
Uses of fermentation
These fermented products use techniques that can make legumes more palatable, increase
nutrient availability and remove toxic components. The fermentation process improves the availability
of essential amino acids. So in general nutritive value of legume base and fermentation food is higher
than their raw counter parts.
·Vitamin B is increased
·Protein quality of product increases
·Anti-physiological factors in legumes are eliminated
Rice
Decorticated
Black Gram
Dhal
Washed
Soaked 5-10 hr
(Room Temperature)
Grind with water to
give paste
Grind with water to give
smooth gelatinous paste
Mixed Salt (0.8%)
Thick Batter
Fermented at room temperature
overnight
Batter placed in steamer and
steamed
Served Hot
Flow Sheet of preparation of idli by fermentation
e-- [email protected] Page 133 of 162
A mungo bean-based product, Idli, made from mungo beans and rice is popular in southern
India. Idli is prepared by washing, soaking and grinding rice and mungo beans, followed by mixing.
The proportions of rice to beans varied from 4 parts beans: 1 part rice to 1 part beans: 4 parts rice. The
mix is allowed to ferment overnight. No inoculum is needed because the naturally present flora is
sufficient to carryout the fermentation. Leuconostoc mesenteroides is the predominant microorganism
and Streptococcus faecalis and Pediococcus are also present. The fermented idli is steamed and served
hot.
3) Soya bean paste (miso)
Soyabean paste is mostly a Japanese product. The fermenting agent, as in soya sauce, is
Aspergillus oryzae. The ingredients are cooked soyabean and steamed rice or barley, and the mixture
is fermented from 2 weeks to years. The rate of fermentation is controlled by the addition of salt.
It is used in the preparation of soups or served with rice and other foods as dressings or a side dish.
Uses of fermentation
These fermented products use techniques that can make legumes more palatable, increase
nutrient availability and remove toxic components. The fermentation process improves the availability
of essential amino acids. So in general nutritive value of legume base and fermentation food is higher
than their raw counter parts.
·Vitamin B is increased
·Protein quality of product increases
·Anti-physiological factors in legumes are eliminated
Rice
Decorticated
Black Gram
Dhal
Washed
Soaked 5-10 hr
(Room Temperature)
Grind with water to
give paste
Grind with water to give
smooth gelatinous paste
Mixed Salt (0.8%)
Thick Batter
Fermented at room temperature
overnight
Batter placed in steamer and
steamed
Served Hot
Flow Sheet of preparation of idli by fermentation
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 134 of 162
Mixture of grain legume and cereal has very good nutritional possibilities.
SOME ANTINUTRITIONAL FACTORS
1.Trypsin inhibitors: Present-in soyabean, peanut, chickpea etc.
Mode of action: causes pancreatic hypertrophy.
2. Haemagglutinis Ricin and concanavalin A present in lentil, castor bean, soyabean,
Haemagglutinis combine with mucosal cells lining the intestinal wall and thereby interfere with the
absorption of essential nutrients.
3. Osteolathyrogens Present in Lathyrus oderatus affects bone and connective tissue.
4. Neurolathyrogens: Present in Lathyrus sativus damage central nervous system.
5. Saponins: Present in soyabean, peanut. They have haemolytic activity. They inhibit the
proteolytic activities of trypsin and chrymotrypsin.
Polished Rice
Washed
Soaked
Excess water drained
Steamed
Cooled at 35º C
Soybean
Crushed in roller in grits
Washed
Soaked in water for 2.5 hrs
Excess water drained
Steamed (1 hr 5 lb)
(Moisture 57.2%)
Innoculated with
Aspergillus oryzae
Incubated with
Koji (Mold Rice)
50 hrs at 27º or 28º C
Mixing
Fermented (7 days 28º C)
(2 months 35º C)
Ripened (2 Weeks at room
temperature)
Blended and Mashed
Flow Sheet of preparation of Miso by fermentation
NaCl
Innoculum
Miso
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Mixture of grain legume and cereal has very good nutritional possibilities.
SOME ANTINUTRITIONAL FACTORS
1.Trypsin inhibitors: Present-in soyabean, peanut, chickpea etc.
Mode of action: causes pancreatic hypertrophy.
2. Haemagglutinis Ricin and concanavalin A present in lentil, castor bean, soyabean,
Haemagglutinis combine with mucosal cells lining the intestinal wall and thereby interfere with the
absorption of essential nutrients.
3. Osteolathyrogens Present in Lathyrus oderatus affects bone and connective tissue.
4. Neurolathyrogens: Present in Lathyrus sativus damage central nervous system.
5. Saponins: Present in soyabean, peanut. They have haemolytic activity. They inhibit the
proteolytic activities of trypsin and chrymotrypsin.
Polished Rice
Washed
Soaked
Excess water drained
Steamed
Cooled at 35º C
Soybean
Crushed in roller in grits
Washed
Soaked in water for 2.5 hrs
Excess water drained
Steamed (1 hr 5 lb)
(Moisture 57.2%)
Innoculated with
Aspergillus oryzae
Incubated with
Koji (Mold Rice)
50 hrs at 27º or 28º C
Mixing
Fermented (7 days 28º C)
(2 months 35º C)
Ripened (2 Weeks at room
temperature)
Blended and Mashed
Flow Sheet of preparation of Miso by fermentation
NaCl
Innoculum
Miso
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 135 of 162
6. Favism: Favism is haemolytic anaemia. The disease is almost entirely confined to persons living
in the Mediterranean basin. In severe of favism, death may occur with in 24-48 hrs. of the onset of the
attack. Children are more liable to succumb than adults. Favism is brought about by eating broad
beans or by inhaling the pollen of the flower.
7. Lathyrism: Lathyrism is a paralytic disease. The incidence of the disease is higher in males than
females and recovery from the condition does not usually occur. The disease has been associated with
consumption of Khesari dhal. However Lathyrism develops only when the consumption of dhal is
high and the diet does not contain adequate quantities of cereals.
8. Alkaloids present in various legumes interfere with the digestibility.
9. Oligosaccharides of the raffinose family, present in mature legume seeds at levels of 1-6% are
thought to be responsible for flatulence.
Elimination of antinutritional factors by processing It has already been indicated that soaking,
heating and fermentation can reduce or eliminate most of the toxic factors of the pulses. Correct
application of heat in cooking pulses can eliminate most toxic factors without impairment of
nutritional value. Cooking also contributes towards pulse digestibility. Heat causes the denaturation of
the proteins responsible for trypsin inhibition, haemagglutination and the enzyme responsible for the
hydrolysis of cyanogenic glycoides. The mode of application of heat is important. Autoclaving and
soaking followed by heating and effective. Another way of eliminating toxic factors is by
fermentation, which yields products more digestible and of higher nutritive value than the raw pulses.
Removal of antinutritional factors of chickpea and pigeonpea
1) Protease inhibitors
The inhibitory activities of chickpea and pigeonpea are more heat-labile under acidic
conditions and are completely destroyed only when subjected to heat under acidic conditions. Trypsin
inhibitors of chickpea were inactivated by moist heat at 121ºC for 30 min but not by dry heat.
Preliminary soaking followed by dry heat treatment resulted in partial inactivation of the inhibitor
trypsin activity.
2. Amylase inhibitors
Pigeonpea seed extracts showed remarkably higher amylase inhibitor activity (22-45 units/g) in
comparison with chickpea (4-6 units/g). They were inactivated when extracts were boiled for 10
minutes.
3. Phytolectins
These are toxic factors that interact with glycoproteins on the surface of red blood cells and
causing them to agglutinate. These are highly sensitive to heat treatment. In chickpea, almost complete
reduction of hemagglutinating activity was obtained with moist heat at 100ºC whereas soaking alone
had little effect. A complete destruction was achieved by autoclaving at 12 1 'C for 3 0 min. Their
activity is completely destroyed by moist heat treatment, which is commonly given to the pulses
before consumption.
4. Polyphenols
Polyphenols of dry beans decreased protein digestibility in animals and humans probably by
making protein partially unavailable or by inhibiting digestive enzymes. Both chickpea and pigeonpea
contain considerable amount of polyphenolic compounds. Fifty per cent of these compounds were lost
in chickpea and pigeonpea as a result of overnight soaking in water and when germination was
contained for 48 hr a further 10 per cent was observed. Also cooking without prior soaking-brought
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6. Favism: Favism is haemolytic anaemia. The disease is almost entirely confined to persons living
in the Mediterranean basin. In severe of favism, death may occur with in 24-48 hrs. of the onset of the
attack. Children are more liable to succumb than adults. Favism is brought about by eating broad
beans or by inhaling the pollen of the flower.
7. Lathyrism: Lathyrism is a paralytic disease. The incidence of the disease is higher in males than
females and recovery from the condition does not usually occur. The disease has been associated with
consumption of Khesari dhal. However Lathyrism develops only when the consumption of dhal is
high and the diet does not contain adequate quantities of cereals.
8. Alkaloids present in various legumes interfere with the digestibility.
9. Oligosaccharides of the raffinose family, present in mature legume seeds at levels of 1-6% are
thought to be responsible for flatulence.
Elimination of antinutritional factors by processing It has already been indicated that soaking,
heating and fermentation can reduce or eliminate most of the toxic factors of the pulses. Correct
application of heat in cooking pulses can eliminate most toxic factors without impairment of
nutritional value. Cooking also contributes towards pulse digestibility. Heat causes the denaturation of
the proteins responsible for trypsin inhibition, haemagglutination and the enzyme responsible for the
hydrolysis of cyanogenic glycoides. The mode of application of heat is important. Autoclaving and
soaking followed by heating and effective. Another way of eliminating toxic factors is by
fermentation, which yields products more digestible and of higher nutritive value than the raw pulses.
Removal of antinutritional factors of chickpea and pigeonpea
1) Protease inhibitors
The inhibitory activities of chickpea and pigeonpea are more heat-labile under acidic
conditions and are completely destroyed only when subjected to heat under acidic conditions. Trypsin
inhibitors of chickpea were inactivated by moist heat at 121ºC for 30 min but not by dry heat.
Preliminary soaking followed by dry heat treatment resulted in partial inactivation of the inhibitor
trypsin activity.
2. Amylase inhibitors
Pigeonpea seed extracts showed remarkably higher amylase inhibitor activity (22-45 units/g) in
comparison with chickpea (4-6 units/g). They were inactivated when extracts were boiled for 10
minutes.
3. Phytolectins
These are toxic factors that interact with glycoproteins on the surface of red blood cells and
causing them to agglutinate. These are highly sensitive to heat treatment. In chickpea, almost complete
reduction of hemagglutinating activity was obtained with moist heat at 100ºC whereas soaking alone
had little effect. A complete destruction was achieved by autoclaving at 12 1 'C for 3 0 min. Their
activity is completely destroyed by moist heat treatment, which is commonly given to the pulses
before consumption.
4. Polyphenols
Polyphenols of dry beans decreased protein digestibility in animals and humans probably by
making protein partially unavailable or by inhibiting digestive enzymes. Both chickpea and pigeonpea
contain considerable amount of polyphenolic compounds. Fifty per cent of these compounds were lost
in chickpea and pigeonpea as a result of overnight soaking in water and when germination was
contained for 48 hr a further 10 per cent was observed. Also cooking without prior soaking-brought
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 136 of 162
about a 70 per cent decrease in the polyphenolic compounds of chickpea and pigeonpea when cooking
water was discarded,
5. Oligosaccharides
It includes stachyose, raffinose and verbascose, which contribute to flatulence in man and
animals. Flatulence is characterized by the production of high amounts of carbon dioxide, hydrogen
and small amounts of methane gas. Germinated chickpea and pigeonpea produce less flatus than
ungerminated. Sixty one per cent decrease was observed in the level of raffinose and stachyose by
germination. Germination followed by cooking brought about 60 percent reductions in oligosaccharide
levels in chickpea and 70 per cent in pigeonpea. There was also a significant reduction in the raffinose
by fermentation.
MODERN CFTRI METHOD OF PULSE MILLING
1) Cleaning
Cleaning is done in rotary reel cleaners to remove all impurities from pulses and separate them
according to size.
2) Preconditioning
The cleaned pulses are conditioned in two passes iii a dryer using hot air at about 120ºC for a
certain period of time. After each pass, the hot pulses are tempered in the tempering bins for about six
hours. The preconditioning of pulses helps in loosening husk significantly.
3) Dehusking
The preconditioned are conveyed to the pearler or dehusker where almost all pulses are dehusked
in a single operation. The dehusked whole pulses (gota) are separated from split pulses and mixture of
husk, brokens etc. and are received in a screw conveyor where water is added at a controlled rate. The
moistened gota is then collected on the floor and allowed to remain as such for about an hour.
4) Lump breaking
Some of the moistened gota from into lumps of various sizes. These lumps are fed to the Jump
breaker to break them.
5) Conditioning and splitting
After lump breaking the gota is conveyed or a few hours. The gota is thus dried to the proper
moisture level for splitting. The hot conditioned and dried dehusked whole pulses are split in the
emery roller. All of them are not split in one pass. The mixture is graded into grade I pulses, dehusked
whole pulses and small brokens. The unsplit dehusked pulses are again fed to the conditioner for
subsequent splitting.
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about a 70 per cent decrease in the polyphenolic compounds of chickpea and pigeonpea when cooking
water was discarded,
5. Oligosaccharides
It includes stachyose, raffinose and verbascose, which contribute to flatulence in man and
animals. Flatulence is characterized by the production of high amounts of carbon dioxide, hydrogen
and small amounts of methane gas. Germinated chickpea and pigeonpea produce less flatus than
ungerminated. Sixty one per cent decrease was observed in the level of raffinose and stachyose by
germination. Germination followed by cooking brought about 60 percent reductions in oligosaccharide
levels in chickpea and 70 per cent in pigeonpea. There was also a significant reduction in the raffinose
by fermentation.
MODERN CFTRI METHOD OF PULSE MILLING
1) Cleaning
Cleaning is done in rotary reel cleaners to remove all impurities from pulses and separate them
according to size.
2) Preconditioning
The cleaned pulses are conditioned in two passes iii a dryer using hot air at about 120ºC for a
certain period of time. After each pass, the hot pulses are tempered in the tempering bins for about six
hours. The preconditioning of pulses helps in loosening husk significantly.
3) Dehusking
The preconditioned are conveyed to the pearler or dehusker where almost all pulses are dehusked
in a single operation. The dehusked whole pulses (gota) are separated from split pulses and mixture of
husk, brokens etc. and are received in a screw conveyor where water is added at a controlled rate. The
moistened gota is then collected on the floor and allowed to remain as such for about an hour.
4) Lump breaking
Some of the moistened gota from into lumps of various sizes. These lumps are fed to the Jump
breaker to break them.
5) Conditioning and splitting
After lump breaking the gota is conveyed or a few hours. The gota is thus dried to the proper
moisture level for splitting. The hot conditioned and dried dehusked whole pulses are split in the
emery roller. All of them are not split in one pass. The mixture is graded into grade I pulses, dehusked
whole pulses and small brokens. The unsplit dehusked pulses are again fed to the conditioner for
subsequent splitting.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 137 of 162
e-- [email protected] Page 137 of 162
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 138 of 162
e-- [email protected] Page 138 of 162
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 139 of 162
e-- [email protected] Page 139 of 162
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 140 of 162
BREAKFAST CEREA.LS
History of the Industry
It is both convenient and logical to categorize breakfast cereals as
(1) Those products such as oatmeal, which are served hot and therefore are expected to be cooked
before they are served, and
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BREAKFAST CEREA.LS
History of the Industry
It is both convenient and logical to categorize breakfast cereals as
(1) Those products such as oatmeal, which are served hot and therefore are expected to be cooked
before they are served, and
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 141 of 162
(2) Fully cooked ready-to- eat cereals such as corn flakes which are rarely, if ever, heated before
serving.
The original motivation for the development of precooked breakfast foods seems to have been
the desire of some vegetarians to add more variety to their diets.
The first ready-to-eat breakfast cereal was probably "Granula," developed by Dr. James C.
Jackson about 1863. Jackson's health food was made by rolling coarse whole meal dough into thin
sheets which were baked until they were hard and brittle. The crisp cookies material was broken and
ground into small chunks, the chunks were again baked and finally fragmented into small granules.
PROCESSING OF HOT-SERVE CEREALS
There are two processing steps which are common to the manufacture of nearly all uncooked
breakfast cereals. One of these is the reduction of particle size and the other is the elimination from
the raw material of some of the fibrous substances found in the whole grain.
The effect of these operations is to reduce cooking time and to improve the texture and perhaps
the digestibility of the cooked food. There is usually no attempt to alter materially the natural flavor of
the grain by hydrolyzing its starches or caramelizing its sugars, although it is true the heat treatment
often applied to oatmeal changes its flavor somewhat.
Many consumers find the cooking time required for preparing meals using ingredients
containing unaltered grain products to be excessive. To increase convenience, and therefore consumer
acceptance, it is highly desirable to decrease the time required for kitchen preparation. Ideally, it
should be possible to pour boiling water on the cereal, stir the mixture an few times, and then consume
it. This ideal has been achieved with some modifications of oatmeal and wheat farina, although, it is
true that the texture of the finished product is not quite the same as that obtained by cooking the
unmodified granules.
Some hot-serve cereals are made from mixed grains which have been precooked and then
dried, or from a combination of grains with other ingredients such as nonfat dry milk. Cereals for
infant feeding may be precooked mixtures of ingredients which are dried in thin flake form. These
flakes can be quickly rehydrated by adding the proper amount of hot water and stirring briefly. The
consistency or texture of such materials is generally not appreciated by most adults, since the cereals
as served tend to be somewhat pasty and sticky.
Wheat Cereals
The uncooked wheat cereal having the largest consumption is farina, a typical example being
Cream of Wheat. This product is nothing more than the wheat middlings which are described in
greater detail in the chapter on Milling. Middlings are chunks of endosperm for all practical purposes
free of bran and germ. When reduced in size, middlings become flour. In the manufacture of farina for
breakfast cereal, it is necessary to use hard wheat as a raw material since soft wheat yields a product
which becomes excessively pasty upon cooking. About 30º-70º F the wheat coming into a mill can be
obtained as farina by good milling techniques. It is seldom, if ever, that wheat is milled specifically for
the purpose of obtaining farina.
Particle size is thought to be a critical factor influencing consumer acceptance. All the farina
should pass through a U. S, Standard No. 20 woven wire cloth sieve; not more than 10.0% should pass
through a No. 45 sieve; and not more than 30.0% should pass through a No. 100 sieve. Vitamin and
mineral enrichment is usually applied to farina. Vitamins are normally added in the dry state which
seems to be satisfactory in practice but does give some opportunity for separation in the package.
Disodium phosphate has been used (at about the 0.25% level) to increase the rate at which
farina cooks. Other steps are required to get an "instant" farina which is ready to eat after about one
minute of cooking time. One method of decreasing cooking time is to apply proteolytic enzymes (such
as bromelin) or fungal enzymes so that microscopic pathways for water penetration are formed in the
granule.
Farina flavored with dried malt syrup or with cocoa is marketed. Generally, these products are
simple mixtures of the dry flavoring ingredients with middlings.
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(2) Fully cooked ready-to- eat cereals such as corn flakes which are rarely, if ever, heated before
serving.
The original motivation for the development of precooked breakfast foods seems to have been
the desire of some vegetarians to add more variety to their diets.
The first ready-to-eat breakfast cereal was probably "Granula," developed by Dr. James C.
Jackson about 1863. Jackson's health food was made by rolling coarse whole meal dough into thin
sheets which were baked until they were hard and brittle. The crisp cookies material was broken and
ground into small chunks, the chunks were again baked and finally fragmented into small granules.
PROCESSING OF HOT-SERVE CEREALS
There are two processing steps which are common to the manufacture of nearly all uncooked
breakfast cereals. One of these is the reduction of particle size and the other is the elimination from
the raw material of some of the fibrous substances found in the whole grain.
The effect of these operations is to reduce cooking time and to improve the texture and perhaps
the digestibility of the cooked food. There is usually no attempt to alter materially the natural flavor of
the grain by hydrolyzing its starches or caramelizing its sugars, although it is true the heat treatment
often applied to oatmeal changes its flavor somewhat.
Many consumers find the cooking time required for preparing meals using ingredients
containing unaltered grain products to be excessive. To increase convenience, and therefore consumer
acceptance, it is highly desirable to decrease the time required for kitchen preparation. Ideally, it
should be possible to pour boiling water on the cereal, stir the mixture an few times, and then consume
it. This ideal has been achieved with some modifications of oatmeal and wheat farina, although, it is
true that the texture of the finished product is not quite the same as that obtained by cooking the
unmodified granules.
Some hot-serve cereals are made from mixed grains which have been precooked and then
dried, or from a combination of grains with other ingredients such as nonfat dry milk. Cereals for
infant feeding may be precooked mixtures of ingredients which are dried in thin flake form. These
flakes can be quickly rehydrated by adding the proper amount of hot water and stirring briefly. The
consistency or texture of such materials is generally not appreciated by most adults, since the cereals
as served tend to be somewhat pasty and sticky.
Wheat Cereals
The uncooked wheat cereal having the largest consumption is farina, a typical example being
Cream of Wheat. This product is nothing more than the wheat middlings which are described in
greater detail in the chapter on Milling. Middlings are chunks of endosperm for all practical purposes
free of bran and germ. When reduced in size, middlings become flour. In the manufacture of farina for
breakfast cereal, it is necessary to use hard wheat as a raw material since soft wheat yields a product
which becomes excessively pasty upon cooking. About 30º-70º F the wheat coming into a mill can be
obtained as farina by good milling techniques. It is seldom, if ever, that wheat is milled specifically for
the purpose of obtaining farina.
Particle size is thought to be a critical factor influencing consumer acceptance. All the farina
should pass through a U. S, Standard No. 20 woven wire cloth sieve; not more than 10.0% should pass
through a No. 45 sieve; and not more than 30.0% should pass through a No. 100 sieve. Vitamin and
mineral enrichment is usually applied to farina. Vitamins are normally added in the dry state which
seems to be satisfactory in practice but does give some opportunity for separation in the package.
Disodium phosphate has been used (at about the 0.25% level) to increase the rate at which
farina cooks. Other steps are required to get an "instant" farina which is ready to eat after about one
minute of cooking time. One method of decreasing cooking time is to apply proteolytic enzymes (such
as bromelin) or fungal enzymes so that microscopic pathways for water penetration are formed in the
granule.
Farina flavored with dried malt syrup or with cocoa is marketed. Generally, these products are
simple mixtures of the dry flavoring ingredients with middlings.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 142 of 162
Whole wheat meal, cracked wheat, flaked wheat, and farina with bran and germ are sold
as hot cereals to a rather limited extent. The shelf-life of these materials is limited by the tendency of
germ oils to become rancid unless the product is specially processed.
An instant cook-in-the-bowl cereal made from wheat was described by Spring (1971). Wheat,
preferably hard red winter wheat, is milled to a particle size such that at least 90% of it passes through
a No. 12 Tyler mesh screen and less than 10% through a 42 mesh screen. The milled fraction is
tempered to a moisture content of 15 to 16% and a temperature of 185 to 220°F, and then flaked to
0.007 to 0.008 inch thick by passing the particles between a set of flaking rolls having a slight pressure
differential. The flaked grain is then dried to a moisture content of 8 to 9%. The cereal rehydrates
readily when mixed with boiling water in a serving bowl.
Corn Cereals
Corn grits is the maize analogue of farina. For all practical purposes, it is just the endosperm of
com ground into medium coarse granules. Large amounts of grits are consumed in the southern states.
They are served with sugar and milk or cream as a breakfast cereal ("mush"). They can also be served
as a potato or rice substitute at the noon and evening meals, often being topped with butter or gravy
("grits"). Grits are generally cooked with water, only salt being added. The boiled grits can be allowed
to cool and the congealed mass sliced into fairly thick strips and fried (with or without preliminary
flouring) to give a culinary delight which is served with syrup or gravy topping.
Corn grits is one of the products obtained in dry milling of corn kernels, a process which is
described in considerable detail in a preceding chapter.
Oat Cereals
The typical commercial oat products used as breakfast cereals or breakfast cereal ingredients
can be categorized as (Webster 1986):
1. Rolled oats, produced by flaking whole groats. These are the thickest of standard oat-flake
products. Flake thickness varies from 0.020 to 0.030 inch, depending on the intended use. Thicker
flakes require longer cooking times and maintain flake integrity during extended holding times.
2. Steel-cut groats are produced by the sectioning of groats into several pieces by a kind of cutting
action (as contrasted to crushing); they are used in the preparation of flakes and flour and as a
specialty ingredient.
3. Quick oats are flakes produced from steel-cut groats. In this process, oat groats are typically cut
into three or four pieces before the final steaming and flaking processes. Quick oats, which are usually
0.014 to 0.018 -inch thick, require less cooking time than whole-oat flakes.
4. Baby oats are also produced from steel-cut groats, but the flakes are thinner and have a smaller
particle size than quick oats. These smaller, thinner flakes cook more rapidly than quick oats and have
a smoother texture.
5. Instant oat flakes are produced from "instantized" steel-cut groats. Before cutting, the groats are
subjected to a special proprietary process that allows them to acquire a satisfactory eating consistency
after a relatively short cooking time. These flakes are typically 0.011 to 0.013 inch thick.
6. Oat flour is produced by grinding flakes or groats into flour for use as an ingredient in a wide
variety of food products.
7. Oat bran is a bran-rich fraction produced by sieving coarsely ground oat flour.
In 1990, a committee of the American Association of Cereal Chemists adopted the following
definition of oat bran: "Oat bran is the food which is produced by grinding clean oat groats or rolled
oats and separating the resulting oat flour by sieving, bolting, and/or such other suitable means into
fractions such that the oat bran fraction is not more than 50% of the starting material, and has a total
glucan content of at least 5.5% (dry weight basis) and a total dietary fiber content of at least 16% (dry
weight basis), and such that at least one-third of the total dietary fiber is soluble fiber."
Oat processing for food involves at least the steps of cleaning, hull removal, steaming, and
flaking. Cleaning requires that weed seeds, dirt, and other unwanted materials be removed; this is
accomplished through separation of the rubbish by screening, air flotation, and classification by
particle shape. Then, the oats are graded by size and reduced in moisture content to permit efficient
removal of the hulls. Hulls are then abraded or knocked off the seed by specialized equipment.
e-- [email protected] Page 142 of 162
Whole wheat meal, cracked wheat, flaked wheat, and farina with bran and germ are sold
as hot cereals to a rather limited extent. The shelf-life of these materials is limited by the tendency of
germ oils to become rancid unless the product is specially processed.
An instant cook-in-the-bowl cereal made from wheat was described by Spring (1971). Wheat,
preferably hard red winter wheat, is milled to a particle size such that at least 90% of it passes through
a No. 12 Tyler mesh screen and less than 10% through a 42 mesh screen. The milled fraction is
tempered to a moisture content of 15 to 16% and a temperature of 185 to 220°F, and then flaked to
0.007 to 0.008 inch thick by passing the particles between a set of flaking rolls having a slight pressure
differential. The flaked grain is then dried to a moisture content of 8 to 9%. The cereal rehydrates
readily when mixed with boiling water in a serving bowl.
Corn Cereals
Corn grits is the maize analogue of farina. For all practical purposes, it is just the endosperm of
com ground into medium coarse granules. Large amounts of grits are consumed in the southern states.
They are served with sugar and milk or cream as a breakfast cereal ("mush"). They can also be served
as a potato or rice substitute at the noon and evening meals, often being topped with butter or gravy
("grits"). Grits are generally cooked with water, only salt being added. The boiled grits can be allowed
to cool and the congealed mass sliced into fairly thick strips and fried (with or without preliminary
flouring) to give a culinary delight which is served with syrup or gravy topping.
Corn grits is one of the products obtained in dry milling of corn kernels, a process which is
described in considerable detail in a preceding chapter.
Oat Cereals
The typical commercial oat products used as breakfast cereals or breakfast cereal ingredients
can be categorized as (Webster 1986):
1. Rolled oats, produced by flaking whole groats. These are the thickest of standard oat-flake
products. Flake thickness varies from 0.020 to 0.030 inch, depending on the intended use. Thicker
flakes require longer cooking times and maintain flake integrity during extended holding times.
2. Steel-cut groats are produced by the sectioning of groats into several pieces by a kind of cutting
action (as contrasted to crushing); they are used in the preparation of flakes and flour and as a
specialty ingredient.
3. Quick oats are flakes produced from steel-cut groats. In this process, oat groats are typically cut
into three or four pieces before the final steaming and flaking processes. Quick oats, which are usually
0.014 to 0.018 -inch thick, require less cooking time than whole-oat flakes.
4. Baby oats are also produced from steel-cut groats, but the flakes are thinner and have a smaller
particle size than quick oats. These smaller, thinner flakes cook more rapidly than quick oats and have
a smoother texture.
5. Instant oat flakes are produced from "instantized" steel-cut groats. Before cutting, the groats are
subjected to a special proprietary process that allows them to acquire a satisfactory eating consistency
after a relatively short cooking time. These flakes are typically 0.011 to 0.013 inch thick.
6. Oat flour is produced by grinding flakes or groats into flour for use as an ingredient in a wide
variety of food products.
7. Oat bran is a bran-rich fraction produced by sieving coarsely ground oat flour.
In 1990, a committee of the American Association of Cereal Chemists adopted the following
definition of oat bran: "Oat bran is the food which is produced by grinding clean oat groats or rolled
oats and separating the resulting oat flour by sieving, bolting, and/or such other suitable means into
fractions such that the oat bran fraction is not more than 50% of the starting material, and has a total
glucan content of at least 5.5% (dry weight basis) and a total dietary fiber content of at least 16% (dry
weight basis), and such that at least one-third of the total dietary fiber is soluble fiber."
Oat processing for food involves at least the steps of cleaning, hull removal, steaming, and
flaking. Cleaning requires that weed seeds, dirt, and other unwanted materials be removed; this is
accomplished through separation of the rubbish by screening, air flotation, and classification by
particle shape. Then, the oats are graded by size and reduced in moisture content to permit efficient
removal of the hulls. Hulls are then abraded or knocked off the seed by specialized equipment.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 143 of 162
The next step is flaking. The groats are steamed before flaking to inactivate enzymes and
increase the moisture content. Flaking rollers are about 14 inches in diameter and 28 inches wide; one
roller in each pair is fixed and the other is movable so the gap between each pair of rollers can be
adjusted. There is a scraper knife on each roll to remove the flakes. The cylinders are often made of
chilled iron or centrifugal alloy-iron castings.
Whole groats may be flaked, or they may be first cut into pieces by rotary granulators. The
smaller the piece size and the thinner the flake, the quicker the cereal can be cooked. For example, so-
called "quick" oats, which are flakes made from a particle about one-fourth to one-third the size of a
whole groat, will cook in about five minutes, while flaked whole groats ("regular oats") require ten
to fifteen minutes boiling before they are soft enough to satisfy most consumer's requirements. The
smaller particles do not stand up as well under prolonged heating, however. Thus, regular oats will
maintain a satisfactory texture for about three hours in the steam table of a cafeteria, while quick oats
become unsatisfactory after about one hour under these conditions. By making an even thicker (than
regular oats) flake from the whole groat, oats withstanding six, hours of heating can be obtained, and
steel-cut oats (not flaked) are even more resistant to overcooking.
Instant oats are generally prepared by cooking or gelatinizing flaked oats, then reducing the
particle size and thickness. These steps greatly enhance water penetration and reduce the need for
kitchen cooking to gelatinize the starch.
Pan-toasted oats are subjected to additional heat treatment in gas- heated open "pans" to give
a slightly more caramelized or toasted flavor.
Other Grains as Hot Cereals
Whole milled rice is occasionally cooked as a breakfast cereal. Full details on whole milled
rice are given in the chapter on Rice Processing. There is also an analogue of wheat farina called
Cream of Rice, which consists of milled rice or broken rice which has been ground into particles
about the size of those used in Cream of Wheat. The smaller particle size leads to much quicker
cooking, compared to whole grain rice, so that the product is essentially instant, that is, it does not
require additional heating after the addition of boiling water. A short period of standing after the
addition of water is necessary, of course, to allow complete hydration of the granules. Most consumers
would doubtless prefer the texture of product given a short cook.
In the Orient, one encounters the product called congee, which is whole rice or broken rice
made into a fairly thin gruel. It is usually eaten for breakfast with condiments such as raw eggs,
chopped onions, or dried fish. Cooking with water, and presumably some salt, is the means of
preparing this food.
There is a retail pack of coarse rye meal, called Cream of Rye, in a container very similar in
appearance to the traditional cylindrical oatmeal box, which has a very small share of the hot cereal
market and is found in very few outlets. There is also a Roman Meal cook able breakfast cereal
consisting of a mixture of grains in small granule form.
Pre-cooked Hot Cereals
As described above, and also in the chapter on cereals for special dietary needs, for many
years’ methods have been available for making "instantly" rehydratable cooked cereals. These
methods consist essentially of cooking the cereal, often with additives of a nutritional or flavoring
nature, then drying the mixture, as on a drum dryer, and grinding the product to give small flakes.
Since the flakes are very thin and usually somewhat porous, they allow hot water to penetrate quickly
throughout the particle. Since the starch has been completely gelatinized, further cooking is not
necessary.
PROCESSING READY-TO-EAT BREAKFAST CEREALS
Flakes
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The next step is flaking. The groats are steamed before flaking to inactivate enzymes and
increase the moisture content. Flaking rollers are about 14 inches in diameter and 28 inches wide; one
roller in each pair is fixed and the other is movable so the gap between each pair of rollers can be
adjusted. There is a scraper knife on each roll to remove the flakes. The cylinders are often made of
chilled iron or centrifugal alloy-iron castings.
Whole groats may be flaked, or they may be first cut into pieces by rotary granulators. The
smaller the piece size and the thinner the flake, the quicker the cereal can be cooked. For example, so-
called "quick" oats, which are flakes made from a particle about one-fourth to one-third the size of a
whole groat, will cook in about five minutes, while flaked whole groats ("regular oats") require ten
to fifteen minutes boiling before they are soft enough to satisfy most consumer's requirements. The
smaller particles do not stand up as well under prolonged heating, however. Thus, regular oats will
maintain a satisfactory texture for about three hours in the steam table of a cafeteria, while quick oats
become unsatisfactory after about one hour under these conditions. By making an even thicker (than
regular oats) flake from the whole groat, oats withstanding six, hours of heating can be obtained, and
steel-cut oats (not flaked) are even more resistant to overcooking.
Instant oats are generally prepared by cooking or gelatinizing flaked oats, then reducing the
particle size and thickness. These steps greatly enhance water penetration and reduce the need for
kitchen cooking to gelatinize the starch.
Pan-toasted oats are subjected to additional heat treatment in gas- heated open "pans" to give
a slightly more caramelized or toasted flavor.
Other Grains as Hot Cereals
Whole milled rice is occasionally cooked as a breakfast cereal. Full details on whole milled
rice are given in the chapter on Rice Processing. There is also an analogue of wheat farina called
Cream of Rice, which consists of milled rice or broken rice which has been ground into particles
about the size of those used in Cream of Wheat. The smaller particle size leads to much quicker
cooking, compared to whole grain rice, so that the product is essentially instant, that is, it does not
require additional heating after the addition of boiling water. A short period of standing after the
addition of water is necessary, of course, to allow complete hydration of the granules. Most consumers
would doubtless prefer the texture of product given a short cook.
In the Orient, one encounters the product called congee, which is whole rice or broken rice
made into a fairly thin gruel. It is usually eaten for breakfast with condiments such as raw eggs,
chopped onions, or dried fish. Cooking with water, and presumably some salt, is the means of
preparing this food.
There is a retail pack of coarse rye meal, called Cream of Rye, in a container very similar in
appearance to the traditional cylindrical oatmeal box, which has a very small share of the hot cereal
market and is found in very few outlets. There is also a Roman Meal cook able breakfast cereal
consisting of a mixture of grains in small granule form.
Pre-cooked Hot Cereals
As described above, and also in the chapter on cereals for special dietary needs, for many
years’ methods have been available for making "instantly" rehydratable cooked cereals. These
methods consist essentially of cooking the cereal, often with additives of a nutritional or flavoring
nature, then drying the mixture, as on a drum dryer, and grinding the product to give small flakes.
Since the flakes are very thin and usually somewhat porous, they allow hot water to penetrate quickly
throughout the particle. Since the starch has been completely gelatinized, further cooking is not
necessary.
PROCESSING READY-TO-EAT BREAKFAST CEREALS
Flakes
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 144 of 162
General considerations.-Flaking is a relatively simple process, consisting in its most elemental form
of cooking fragments of cereal grains (or in some cases whole grains) with water, flattening the soft
particles between large steel rollers, and toasting the resultant flake at high temperatures.
Apparently, the first commercial production of such a food occurred around the turn of the
century when J. H. Kellogg and W. H. Kellogg made whole wheat flakes in a barn behind the Battle
Creek Sanitoriurn. Since that time, many complications have been introduced into the process in
attempts to improve the flavor of the product and the efficiency of operations, and to gain the
uniformity of flake size and appearance which is so desirable to the manufacturer and perhaps even to
the consumer.
Flakes owe their popularity with consumers to their crisp but friable texture, to their sweet but
rather bland flavor, and to the ease with which they can be readied for consumption.
In the basic processing steps, the raw material undergoes the following changes:
(1) The starch is gelatinized and probably slightly hydrolyzed;
(2) The particle undergoes a browning reaction due probably to interaction of protein and sugars;
(3) Enzymatic processes are stopped, rendering the final product more stable;
(4) Dextrinization and caramelization of the sugars occur as a result of the high temperatures in the
roasting oven; and
(5) The flake becomes crisper as a result of reduction of its moisture content to a very low level.
Wheat flakes.-Plump kernels of soft wheat are frequently used as the raw material for wheat flakes.
1.After cleaning and sorting according to size, the kernels are tempered in steel bins of small
diameter by adding moisture and holding at about 80°F for about 24 hr.
2.After tempering, the wheat is steamed at atmospheric pressure until it reaches 203°F and 21%
moisture.
3.The steamed wheat is bumped between smooth steel rollers set considerably farther apart than
are flaking rollers. This treatment flattens the grain slightly, and ruptures the bran coat in
several places making the kernel more permeable to the moisture which will be added during
the cooking step.
4.Next, the flattened kernels are transferred to pressure cookers, which are similar to those used
for com flakes, and the other ingredients are added. These ingredients normally include sugars,
salt, malt, and sometimes a coloring substance such as caramel. The retort contents are cooked
at 20 psi steam pressure for 90 min while the vessel is slowly rotating. After cooking, the
grains are soft, translucent, and brown. They contain about 45 to 50% moisture. Their starch
has been completely gelatinized, of course.
5.The retort is now opened and rotated so that its contents fall onto a moving belt which transfers
the cooked mass to a chute leading to a "wiggler." The wiggler consists of a horizontal
perforated disc and a rotating arm carrying vertically-oriented rigid fingers around its upper
surface. The clumps of slightly adhering grains are dropped onto the center of the perforated
disc, through which warm air is being blown in an upward direction. The moving fingers break
up the lumps and move individual grains outwardly until they fall from the edge of the disc
into a pneumatic conveyor and are transferred to a horizontal rotating cylinder fitted with
internal layers.
6.In this drier, air at 250° to 300°F is passed over the grain, eventually reducing it to 28 to 31%
moisture content. At this point the grains are still intact and are rather tough and chewy in
texture. Holding bins are used to store this material until it can be transferred to the presses.
Additional processing is needed to secure the desired crispness and flavor.
7.First, the equilibrated or tempered wheat pieces travel through a drier. This could be a Proctor
and Schwarz drier composed of three sections, the first at 280°F, the second at 290°F, and the
third unheated. Rate of movement of the material is adjusted so as to yield an emerging
product of about 21% moisture content. A spray of B-complex vitamins is applied at this stage.
8.Screw conveyors or drag chain conveyors transport the partially dried pellets to the flaking
rollers. Just before they fall into the flaking rolls, the pellets are heated to about 180° to 190°F,
making them more plastic in consistency. The large steel flaking rollers are practically
identical with those used for making corn flakes. The pressure they apply to the pellets
increases the latter's diameter several times and decreases their thickness proportionately.
e-- [email protected] Page 144 of 162
General considerations.-Flaking is a relatively simple process, consisting in its most elemental form
of cooking fragments of cereal grains (or in some cases whole grains) with water, flattening the soft
particles between large steel rollers, and toasting the resultant flake at high temperatures.
Apparently, the first commercial production of such a food occurred around the turn of the
century when J. H. Kellogg and W. H. Kellogg made whole wheat flakes in a barn behind the Battle
Creek Sanitoriurn. Since that time, many complications have been introduced into the process in
attempts to improve the flavor of the product and the efficiency of operations, and to gain the
uniformity of flake size and appearance which is so desirable to the manufacturer and perhaps even to
the consumer.
Flakes owe their popularity with consumers to their crisp but friable texture, to their sweet but
rather bland flavor, and to the ease with which they can be readied for consumption.
In the basic processing steps, the raw material undergoes the following changes:
(1) The starch is gelatinized and probably slightly hydrolyzed;
(2) The particle undergoes a browning reaction due probably to interaction of protein and sugars;
(3) Enzymatic processes are stopped, rendering the final product more stable;
(4) Dextrinization and caramelization of the sugars occur as a result of the high temperatures in the
roasting oven; and
(5) The flake becomes crisper as a result of reduction of its moisture content to a very low level.
Wheat flakes.-Plump kernels of soft wheat are frequently used as the raw material for wheat flakes.
1.After cleaning and sorting according to size, the kernels are tempered in steel bins of small
diameter by adding moisture and holding at about 80°F for about 24 hr.
2.After tempering, the wheat is steamed at atmospheric pressure until it reaches 203°F and 21%
moisture.
3.The steamed wheat is bumped between smooth steel rollers set considerably farther apart than
are flaking rollers. This treatment flattens the grain slightly, and ruptures the bran coat in
several places making the kernel more permeable to the moisture which will be added during
the cooking step.
4.Next, the flattened kernels are transferred to pressure cookers, which are similar to those used
for com flakes, and the other ingredients are added. These ingredients normally include sugars,
salt, malt, and sometimes a coloring substance such as caramel. The retort contents are cooked
at 20 psi steam pressure for 90 min while the vessel is slowly rotating. After cooking, the
grains are soft, translucent, and brown. They contain about 45 to 50% moisture. Their starch
has been completely gelatinized, of course.
5.The retort is now opened and rotated so that its contents fall onto a moving belt which transfers
the cooked mass to a chute leading to a "wiggler." The wiggler consists of a horizontal
perforated disc and a rotating arm carrying vertically-oriented rigid fingers around its upper
surface. The clumps of slightly adhering grains are dropped onto the center of the perforated
disc, through which warm air is being blown in an upward direction. The moving fingers break
up the lumps and move individual grains outwardly until they fall from the edge of the disc
into a pneumatic conveyor and are transferred to a horizontal rotating cylinder fitted with
internal layers.
6.In this drier, air at 250° to 300°F is passed over the grain, eventually reducing it to 28 to 31%
moisture content. At this point the grains are still intact and are rather tough and chewy in
texture. Holding bins are used to store this material until it can be transferred to the presses.
Additional processing is needed to secure the desired crispness and flavor.
7.First, the equilibrated or tempered wheat pieces travel through a drier. This could be a Proctor
and Schwarz drier composed of three sections, the first at 280°F, the second at 290°F, and the
third unheated. Rate of movement of the material is adjusted so as to yield an emerging
product of about 21% moisture content. A spray of B-complex vitamins is applied at this stage.
8.Screw conveyors or drag chain conveyors transport the partially dried pellets to the flaking
rollers. Just before they fall into the flaking rolls, the pellets are heated to about 180° to 190°F,
making them more plastic in consistency. The large steel flaking rollers are practically
identical with those used for making corn flakes. The pressure they apply to the pellets
increases the latter's diameter several times and decreases their thickness proportionately.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 145 of 162
9.After they pass through the rolls, the flakes contain 10 to 15% moisture and are still slightly
flexible. To obtain the necessary crispness, the flakes are toasted and dehydrated to less than
3% moisture content in a drier provided with a perforated metal conveyor belt. There are
typically four temperature zones in the oven; these may include, for example, heated sections
at 310°, 300°, and 280°F, and an unheated section to partially cool the flakes. The decreasing
temperature pattern is said to promote the development of desirable curling and blistering.
Like most breakfast cereals, wheat flakes are susceptible to the development of rancidity after
extended storage. Addition of the common antioxidants BHA and BHT increases shelf life somewhat.
For extruded wheat flakes, they are less satisfactory when added to the pre-mix because the high
temperatures of processing tend to destroy or vaporize the antioxidants. Megremis (1990) reveals that
mixed tocopherols will survive the conditions of extrusion and substantially extend the storage life of
wheat flakes made by this method.
Bran flakes.-Bran flakes constituted a rather minor part of the breakfast cereal market until the recent
fiber craze, when they began to assume a much more important role. Old-fashioned bran flakes were
manufactured by combining a dried portion containing wheat and sufficient amounts of bran to yield
flakes containing about four grams of fiber per ounce of cereal. Use of larger amounts of bran, with
the aim of providing consumers with a product having greater fiber content, leads to grave difficulties
in flaking and soft (not crisp) products. Most cereals of very high bran content are extruded so as to
yield, typically, the shreds sold as "All Bran."
To make bran flakes, the dry wheat and bran are combined with a flavoring syrup containing
sugar, corn syrup, malt, and salt, then cooked until the starch is completely gelatinized. The cooked
particles are partially dried, tempered, flaked by previously described methods, and finally, toasted to
give finished flakes having a thickness of 0.005 to 0.040 inch.
Flakes from other grains.-Because of the comparatively high level of fat in oats, flakes made from
this grain in the conventional way have a unacceptably short storage life. Lilly and Reinhart (1967)
describe a process said to give oat products of satisfactory stability. Oat groats are pressure-cooked
until the starch is gelatinized, and then kneaded while being held at a temperature of 150° to 212°F
until plastic dough is formed. The dough is shaped into flakes about 0.011 inch in thickness and these
are flash dried to 2 to 10% moisture content by contact with air having a temperature in the range of
400° to 800°F.
There does not appear to have ever been a rye flake which gained wide commercial
distribution, but the patent of Gulstad (1971) describes a method for malting such a product. In one
example, clean dry rye kernels having a moisture content of about 8.3% were fed into a continuous
puffing gun at a feed rate of about 10 lb/min. The following gun conditions were used:
·Steam pressure 100 psig, steam temperature 385°F,
·Barrel angle of 3 degrees below the horizontal,
·Barrel rotation of 45 rpm,
·Puffing orifice diameter of 0.5 inch,
·Barrel diameter 10 inches, and
·Barrel length 12 ft.
The puffed rye was milled into flour on a pin mill. Dough was formed by mixing 388 parts of
the rye flour with 54.5 parts sucrose, 11.3 parts salt, and 169 parts water, so as to give a mixture
having a moisture content of about 32.5%. The resulting dough was processed in a piston type
extruder at a pressure of about 2200 psig, and cut into pellets about 0.25 inch in diameter. After the
pellets were surface dried to about 23% moisture, they were passed between a pair of flaking rolls
spaced about 0.020 inches apart, then dried in a belt oven to a moisture content of about 1%.
No reference can be found to flakes made from grain sorghum, although these seeds would be
likely to respond much like the other grains when subjected to the same type of process. Of course,
sorghum grains are much smaller than other cereal kernels, and conditions would have to be adjusted
to take this difference into account.
e-- [email protected] Page 145 of 162
9.After they pass through the rolls, the flakes contain 10 to 15% moisture and are still slightly
flexible. To obtain the necessary crispness, the flakes are toasted and dehydrated to less than
3% moisture content in a drier provided with a perforated metal conveyor belt. There are
typically four temperature zones in the oven; these may include, for example, heated sections
at 310°, 300°, and 280°F, and an unheated section to partially cool the flakes. The decreasing
temperature pattern is said to promote the development of desirable curling and blistering.
Like most breakfast cereals, wheat flakes are susceptible to the development of rancidity after
extended storage. Addition of the common antioxidants BHA and BHT increases shelf life somewhat.
For extruded wheat flakes, they are less satisfactory when added to the pre-mix because the high
temperatures of processing tend to destroy or vaporize the antioxidants. Megremis (1990) reveals that
mixed tocopherols will survive the conditions of extrusion and substantially extend the storage life of
wheat flakes made by this method.
Bran flakes.-Bran flakes constituted a rather minor part of the breakfast cereal market until the recent
fiber craze, when they began to assume a much more important role. Old-fashioned bran flakes were
manufactured by combining a dried portion containing wheat and sufficient amounts of bran to yield
flakes containing about four grams of fiber per ounce of cereal. Use of larger amounts of bran, with
the aim of providing consumers with a product having greater fiber content, leads to grave difficulties
in flaking and soft (not crisp) products. Most cereals of very high bran content are extruded so as to
yield, typically, the shreds sold as "All Bran."
To make bran flakes, the dry wheat and bran are combined with a flavoring syrup containing
sugar, corn syrup, malt, and salt, then cooked until the starch is completely gelatinized. The cooked
particles are partially dried, tempered, flaked by previously described methods, and finally, toasted to
give finished flakes having a thickness of 0.005 to 0.040 inch.
Flakes from other grains.-Because of the comparatively high level of fat in oats, flakes made from
this grain in the conventional way have a unacceptably short storage life. Lilly and Reinhart (1967)
describe a process said to give oat products of satisfactory stability. Oat groats are pressure-cooked
until the starch is gelatinized, and then kneaded while being held at a temperature of 150° to 212°F
until plastic dough is formed. The dough is shaped into flakes about 0.011 inch in thickness and these
are flash dried to 2 to 10% moisture content by contact with air having a temperature in the range of
400° to 800°F.
There does not appear to have ever been a rye flake which gained wide commercial
distribution, but the patent of Gulstad (1971) describes a method for malting such a product. In one
example, clean dry rye kernels having a moisture content of about 8.3% were fed into a continuous
puffing gun at a feed rate of about 10 lb/min. The following gun conditions were used:
·Steam pressure 100 psig, steam temperature 385°F,
·Barrel angle of 3 degrees below the horizontal,
·Barrel rotation of 45 rpm,
·Puffing orifice diameter of 0.5 inch,
·Barrel diameter 10 inches, and
·Barrel length 12 ft.
The puffed rye was milled into flour on a pin mill. Dough was formed by mixing 388 parts of
the rye flour with 54.5 parts sucrose, 11.3 parts salt, and 169 parts water, so as to give a mixture
having a moisture content of about 32.5%. The resulting dough was processed in a piston type
extruder at a pressure of about 2200 psig, and cut into pellets about 0.25 inch in diameter. After the
pellets were surface dried to about 23% moisture, they were passed between a pair of flaking rolls
spaced about 0.020 inches apart, then dried in a belt oven to a moisture content of about 1%.
No reference can be found to flakes made from grain sorghum, although these seeds would be
likely to respond much like the other grains when subjected to the same type of process. Of course,
sorghum grains are much smaller than other cereal kernels, and conditions would have to be adjusted
to take this difference into account.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 146 of 162
Shreds
Shredded wheat biscuits.-The most popular representative of this class is the pillow-shaped shredded
wheat biscuit manufactured by Nabisco. It differs from most other ready-to-eat breakfast cereals in
that it is made from whole grain without the addition of any flavor and without removal of the germ or
bran. Cooking is typically done at atmospheric pressure in boiling water. After one hour or more of
cooking, moisture content of the wheat kernels will have reached 50 to 60% and the grain will be very
soft. Some preliminary drying in louvered ovens may follow, but the whole wheat is not brought much
below 45 to 50% moisture content. The cooked and slightly dried wheat is transferred to stainless steel
bins and tempered for many hours before it goes to the shredding rolls.
The shredding rolls are from 6 to 8 inches in diameter and as wide as the finished biscuit is to
be, thus much smaller than flaking rolls. One of the pair of rolls has a series of 20 shallow
corrugations or ridges running around its periphery. In cross section, these corrugations may be
rectangular, triangular, or a combination of these shapes. The other roll of the pair is smooth-surfaced.
Moist, softened wheat is drawn between these rollers as they rotate, and it issues as continuous strands
of dough. By cutting grooves perpendicular to the circumferential corrugations, shred layers having a
net-like effect can be obtained. Hall and Carpenter (1956) described the preparation of a biscuit having
a lattice-like network of shreds. Their product may also be puffed, giving an additional variation in
texture and appearance.
Biscuits are built up by layering strands on a moving belt which passes under sets of rolls
positioned in tandem. Ten to 18 rolls may be used for circular biscuits, while 22 rolls is a common
number for rectangular biscuits. In the latter case, layered strands are separated into biscuits by
passing them below blunt "knives" which press a thin line of the dough into a solid mass at regular
intervals.
Composite biscuits.-There are many patents describing the operations of the shredding devices used
in the production of shredded wheat and the like. A recent patent (Leibfred 1989) describes a process
for making fruit- filled shredded wheat biscuits having a plurality of textures.
Granules
The breaking up of a loaf or biscuit is one way of forming cereal granules. The other method is
to agglomerate smaller pieces until particles in the desired size range are formed. The first option has
been used for several decades in the production of Grape-Nuts, and involves the balding of a dense
loaf of simple composition which is then dried and ground.
Puffed Cereals
General considerations.-All puffed cereal manufacturing process are based on the rapid generation of
steam within a plasticized mass which then expands. Puffing may be conducted at atmospheric
pressure, as in the preparation of popcorn, or it may involve sudden pressure changes in which a
product heated above the boiling point of water in some sort of retort is rapidly transferred to an area
of lower (e.g., atmospheric) pressure. In both cases, puffing results from the quick conversion of liquid
water to vapor in the interstices of the cereal particle or dough. The cereal is fixed in its expanded state
by the dehydration which results from diffusion of water vapor out of it and also by the cooling. Gun
puffing may result in an increase of apparent volume (bulk density decrease) of 8-fold to 16-fold for
wheat and 6-fold to 8-fold for rice. Oven puffing leads to a smaller increase in volume for corn, about
3-fold to 4-fold.
Puffed products must be maintained at about 3% moisture or less in order to have satisfactory
crispness. Even at 5% moisture a definite toughness becomes evident. These levels are most critical
and hardest to maintain in foods which have been gun-puffed.
Oven-puffed rice.-This product is prepared from whole kernels of domestic short-grain milled rice.
Frequently the rice is parboiled and pearled before being introduced into the puffing plant. Typically, a
e-- [email protected] Page 146 of 162
Shreds
Shredded wheat biscuits.-The most popular representative of this class is the pillow-shaped shredded
wheat biscuit manufactured by Nabisco. It differs from most other ready-to-eat breakfast cereals in
that it is made from whole grain without the addition of any flavor and without removal of the germ or
bran. Cooking is typically done at atmospheric pressure in boiling water. After one hour or more of
cooking, moisture content of the wheat kernels will have reached 50 to 60% and the grain will be very
soft. Some preliminary drying in louvered ovens may follow, but the whole wheat is not brought much
below 45 to 50% moisture content. The cooked and slightly dried wheat is transferred to stainless steel
bins and tempered for many hours before it goes to the shredding rolls.
The shredding rolls are from 6 to 8 inches in diameter and as wide as the finished biscuit is to
be, thus much smaller than flaking rolls. One of the pair of rolls has a series of 20 shallow
corrugations or ridges running around its periphery. In cross section, these corrugations may be
rectangular, triangular, or a combination of these shapes. The other roll of the pair is smooth-surfaced.
Moist, softened wheat is drawn between these rollers as they rotate, and it issues as continuous strands
of dough. By cutting grooves perpendicular to the circumferential corrugations, shred layers having a
net-like effect can be obtained. Hall and Carpenter (1956) described the preparation of a biscuit having
a lattice-like network of shreds. Their product may also be puffed, giving an additional variation in
texture and appearance.
Biscuits are built up by layering strands on a moving belt which passes under sets of rolls
positioned in tandem. Ten to 18 rolls may be used for circular biscuits, while 22 rolls is a common
number for rectangular biscuits. In the latter case, layered strands are separated into biscuits by
passing them below blunt "knives" which press a thin line of the dough into a solid mass at regular
intervals.
Composite biscuits.-There are many patents describing the operations of the shredding devices used
in the production of shredded wheat and the like. A recent patent (Leibfred 1989) describes a process
for making fruit- filled shredded wheat biscuits having a plurality of textures.
Granules
The breaking up of a loaf or biscuit is one way of forming cereal granules. The other method is
to agglomerate smaller pieces until particles in the desired size range are formed. The first option has
been used for several decades in the production of Grape-Nuts, and involves the balding of a dense
loaf of simple composition which is then dried and ground.
Puffed Cereals
General considerations.-All puffed cereal manufacturing process are based on the rapid generation of
steam within a plasticized mass which then expands. Puffing may be conducted at atmospheric
pressure, as in the preparation of popcorn, or it may involve sudden pressure changes in which a
product heated above the boiling point of water in some sort of retort is rapidly transferred to an area
of lower (e.g., atmospheric) pressure. In both cases, puffing results from the quick conversion of liquid
water to vapor in the interstices of the cereal particle or dough. The cereal is fixed in its expanded state
by the dehydration which results from diffusion of water vapor out of it and also by the cooling. Gun
puffing may result in an increase of apparent volume (bulk density decrease) of 8-fold to 16-fold for
wheat and 6-fold to 8-fold for rice. Oven puffing leads to a smaller increase in volume for corn, about
3-fold to 4-fold.
Puffed products must be maintained at about 3% moisture or less in order to have satisfactory
crispness. Even at 5% moisture a definite toughness becomes evident. These levels are most critical
and hardest to maintain in foods which have been gun-puffed.
Oven-puffed rice.-This product is prepared from whole kernels of domestic short-grain milled rice.
Frequently the rice is parboiled and pearled before being introduced into the puffing plant. Typically, a
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 147 of 162
batch of 1,400 lb of rice is weighed into cookers such as are used in the preparation of corn or wheat
flakes. About 53.5 gal of sugar syrup with salt are added, and the mixture is cooked for 5 hr under 15
lb steam pressure. Sometimes non-diastatic malt syrup and enriching ingredients are added before
cooking.
The lumps of cooked rice coming from the retorts are broken up and dried to approximately 25
to 30% moisture content in rotating louvred driers. Then, the moisture is allowed to distribute
uniformly in the grain by storing the partially dried product in stainless steel bins for about 15 hours.
After the individual kernels are separated and again dried so that a moisture content of 18 to
20% is reached, they are passed under a radiant heater which brings the external layers of the rice to a
temperature of about 180°F. This plasticizes the outer layers of the kernel so that they do not split
when the grain is run through the flaking rolls.
Rollers used in the preparation of oven-puffed rice are set relatively far apart so that the
tremendous compression effect necessary in corn flakes manufacture is not achieved. In fact, the rolls
contact only the widest part of the kernel. The "bumped" grains are again tempered, this time for about
24 hr. To secure the puffed effect, the cooled and tempered rice is passed for about 30 to 45 see
through toasting ovens held at 450° to 575°F.
A cereal called "Special K," manufactured by the Kellogg Co., is basically a rice kernel which
is cooked, then coated while in a moistened condition with wheat gluten, wheat germ meal, dried skim
milk, debittered brewers' yeast, and other nutritional additives. Finally, the material is oven-puffed. A
more complete description of the method of manufacture has been given by Thompson and Raymer
(1958).
Gun-puffed products.-The manufacture of a composite cereal by the gun-puffing process will be
described since it includes several concepts not previously treated in this chapter. In the preparation of
Cheerios, com cones, oat flour, and a flavor premix consisting of sugar, coloring substances, flavoring
compounds, etc., are combined in a screw conveyor having interrupted flights. The homogeneous
mixture is dumped through a rotary valve into a continuous steam-jacketed cooker. Water is added by
a metering device so that the product going to the extruder is at 38 to 40% moisture content.
In the extruder, auger-induced pressure forces strands of cooked dough from orifices in a
circular die plate. A knife rotates over the surface of the die, cutting the strands into short pellets
which may or may not have a central hole depending upon the design of the die orifices. These pellets
are transferred to a tumbling cooker which reduces the surface moisture and prevents them from
sticking together. The product is then deposited in a layer about three inches deep on the metal belt of
a Procter and Schwartz oven. Solid pellets of 15 to 16% moisture content can be bumped between
steel rollers to cause the disc shape to have serrated edges. Puffing takes place in so-called guns.
The puffing guns are pressure vessels typically with internal diameters of about six inches and
a length of about 30 inches. They are provided with a steam inlet, a bleed-off valve, and a means for
heating the gun-usually a gas flame directed onto parts of the outer surface. A charge of pellets at 11 to
12% moisture content is dropped into the open end of the gun through a gravity chute leading from
storage bins on the floor above. The end of the gun is sealed by a trip-valve as soon as the charge is
inserted. If the gun is heated by gas flames, it will be slowly rotated during the pressurizing process.
The temperature builds up as part of the water content of the pellets is converted to vapor and the
steam pressure in- creases. In about 5 to 7 min the temperature will reach 500° to 800°F, and the
pressure at the end point may be in the range of 100 to 200 psi.
When pressure reaches the predetermined level, the end of the gun is suddenly opened by a
trigger mechanism and the contents explode into a cage or bin provided with a floor opening leading
to a conveyor belt. The ejected material is still too moist to be a finished product and must be further
dried, usually in a rotating heated cylinder. Finally, the cereal is cooled, inspected for visual defects,
and sent to the packaging line.
The following raw materials can be expanded satisfactorily by appropriate types of extrusion
equipment:
(1) Rice flour-excellent expander; white and bland tasting products; accepts colors and flavors well.
(2) Corn meal or flour-expands well; texture good; retains corn flavor.
(3) Oat flour-high moisture content required if satisfactory expansion is to be obtained; high
temperature also needed.
(4) Wheat flour-high moisture and high temperature required for satisfactory results.
e-- [email protected] Page 147 of 162
batch of 1,400 lb of rice is weighed into cookers such as are used in the preparation of corn or wheat
flakes. About 53.5 gal of sugar syrup with salt are added, and the mixture is cooked for 5 hr under 15
lb steam pressure. Sometimes non-diastatic malt syrup and enriching ingredients are added before
cooking.
The lumps of cooked rice coming from the retorts are broken up and dried to approximately 25
to 30% moisture content in rotating louvred driers. Then, the moisture is allowed to distribute
uniformly in the grain by storing the partially dried product in stainless steel bins for about 15 hours.
After the individual kernels are separated and again dried so that a moisture content of 18 to
20% is reached, they are passed under a radiant heater which brings the external layers of the rice to a
temperature of about 180°F. This plasticizes the outer layers of the kernel so that they do not split
when the grain is run through the flaking rolls.
Rollers used in the preparation of oven-puffed rice are set relatively far apart so that the
tremendous compression effect necessary in corn flakes manufacture is not achieved. In fact, the rolls
contact only the widest part of the kernel. The "bumped" grains are again tempered, this time for about
24 hr. To secure the puffed effect, the cooled and tempered rice is passed for about 30 to 45 see
through toasting ovens held at 450° to 575°F.
A cereal called "Special K," manufactured by the Kellogg Co., is basically a rice kernel which
is cooked, then coated while in a moistened condition with wheat gluten, wheat germ meal, dried skim
milk, debittered brewers' yeast, and other nutritional additives. Finally, the material is oven-puffed. A
more complete description of the method of manufacture has been given by Thompson and Raymer
(1958).
Gun-puffed products.-The manufacture of a composite cereal by the gun-puffing process will be
described since it includes several concepts not previously treated in this chapter. In the preparation of
Cheerios, com cones, oat flour, and a flavor premix consisting of sugar, coloring substances, flavoring
compounds, etc., are combined in a screw conveyor having interrupted flights. The homogeneous
mixture is dumped through a rotary valve into a continuous steam-jacketed cooker. Water is added by
a metering device so that the product going to the extruder is at 38 to 40% moisture content.
In the extruder, auger-induced pressure forces strands of cooked dough from orifices in a
circular die plate. A knife rotates over the surface of the die, cutting the strands into short pellets
which may or may not have a central hole depending upon the design of the die orifices. These pellets
are transferred to a tumbling cooker which reduces the surface moisture and prevents them from
sticking together. The product is then deposited in a layer about three inches deep on the metal belt of
a Procter and Schwartz oven. Solid pellets of 15 to 16% moisture content can be bumped between
steel rollers to cause the disc shape to have serrated edges. Puffing takes place in so-called guns.
The puffing guns are pressure vessels typically with internal diameters of about six inches and
a length of about 30 inches. They are provided with a steam inlet, a bleed-off valve, and a means for
heating the gun-usually a gas flame directed onto parts of the outer surface. A charge of pellets at 11 to
12% moisture content is dropped into the open end of the gun through a gravity chute leading from
storage bins on the floor above. The end of the gun is sealed by a trip-valve as soon as the charge is
inserted. If the gun is heated by gas flames, it will be slowly rotated during the pressurizing process.
The temperature builds up as part of the water content of the pellets is converted to vapor and the
steam pressure in- creases. In about 5 to 7 min the temperature will reach 500° to 800°F, and the
pressure at the end point may be in the range of 100 to 200 psi.
When pressure reaches the predetermined level, the end of the gun is suddenly opened by a
trigger mechanism and the contents explode into a cage or bin provided with a floor opening leading
to a conveyor belt. The ejected material is still too moist to be a finished product and must be further
dried, usually in a rotating heated cylinder. Finally, the cereal is cooled, inspected for visual defects,
and sent to the packaging line.
The following raw materials can be expanded satisfactorily by appropriate types of extrusion
equipment:
(1) Rice flour-excellent expander; white and bland tasting products; accepts colors and flavors well.
(2) Corn meal or flour-expands well; texture good; retains corn flavor.
(3) Oat flour-high moisture content required if satisfactory expansion is to be obtained; high
temperature also needed.
(4) Wheat flour-high moisture and high temperature required for satisfactory results.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 148 of 162
(5) Potato flour-high moisture and high temperature needed.
(6) Tapioca flour-needs high temperature and moderate moisture content.
(7) Defatted Boy flour-requires high temperature and moderate to high moisture.
(8) Full fat soybeans-should have 3 to 5 minutes preconditioning with steam prior to extrusion;
extrude at 250°F.
(9) Plain and arid-modified corn and wheat starches-need medium to high temperatures; use either
steam or water as moisturizer.
As the fat content of the cereal mixture increases, the expansion tends to decrease, but the
pieces become more uniform and their surface becomes smoother and brighter, while the cell size
becomes smaller and more uniform. Monoglycerides seem to increase these effects. Sugars modify the
flavor and texture, and may help to control shape and size of tough doughs.
Alternative puffing methods- Puffing processes depending on contact of dough pieces with very hot
embossed cylinders are in current use. Roll temperatures of 350° to 800°F are said to be within the
practical range, and it is likely that most producers employ temperatures in the upper half of this
range. Rolls may be heated by radiant (infrared) energy or by the circulation of high temperature fluid
media inside the cylinder. In one process (Huber 1955), the dough has a moisture content of 8 to 18%
going into the rolls and 6 -to 7% after puffing. Doughs may be preheated to temperatures below the
boiling point, this technique allowing lower rose temperatures to be used.
Sugar-coated Products
Items which are approximately spherical or disc-shaped, such as puffed wheat and puffed rice,
can be coated by a technique very similar to the pan-coating process used in confectionery
manufacture. The usual apparatus somewhat resembles a cement mixer in having an open bowl
rotating about an axis inclined slightly from the horizontal. The very dry cereal particles are placed in
the bowl and, as it rotates, molten (250°F) sugar syrup is slowly dripped on the bowl's contents. A
small amount of coconut oil may be added to decrease foaming of the sugar syrup and to promote
separation of the coated particles. The tumbling action of the particles results in each of them
remaining separate and becoming uniformly coated with a thin glaze of sugar which hardens upon
cooling. From 25 to 60% of the weight of the finished product is glaze. A stream of hot air is usually
directed into the coating reel to assist in removal of moisture. Some authorities have suggested a syrup
formula of 86% sucrose, 13% corn syrup, and 1% salt. Sometimes 0.01 to 0.05% sodium acetate may
be added to prevent crystallization of the coating.
SNACK FOODS
INTRODUCTION
One dictionary defines a snack as "a slight, hasty repast," while another says it is "a mere bits
or morsel of food, as contrasted with a regular meal; a light or incidental repast." Possibly, neither of
these definitions satisfactorily represents current usage. I have not found "snack food" in any
dictionary, but it is likely that most people would recognize a snack food as being something
consumed primarily for pleasure rather than for social or nutritive purposes and not ordinarily used in
a regular meal. Some foods are used both as snacks and as meal components, pizza being an obvious
example. Snack foods can be either sweet or savory/salty--cookies or crackers, doughnuts or pretzels.
This chapter will deal with those products which are clearly definable as snack foods and which are
not discussed elsewhere in the book-most snacks made by traditional bakery methods will be covered
in the chapter devoted to bakery processing. Only snacks composed in large part of cereals will be
included; this rules out such things as meat snacks (e.g., jerky, sausage sticks), fruit snacks (e.g., fruit
“leathern”), and most confectionery (e.g., chocolates, boiled sweets).
The main subdivisions of this chapter are Popcorn, Formulated Puffed Snacks, and Other
Snacks. To avoid repetition, many details about non-cereal raw materials which have been discussed
previously have been omitted, and it will occasionally be necessary for the reader to refer to other
chapters for details on certain raw materials and equipment.
e-- [email protected] Page 148 of 162
(5) Potato flour-high moisture and high temperature needed.
(6) Tapioca flour-needs high temperature and moderate moisture content.
(7) Defatted Boy flour-requires high temperature and moderate to high moisture.
(8) Full fat soybeans-should have 3 to 5 minutes preconditioning with steam prior to extrusion;
extrude at 250°F.
(9) Plain and arid-modified corn and wheat starches-need medium to high temperatures; use either
steam or water as moisturizer.
As the fat content of the cereal mixture increases, the expansion tends to decrease, but the
pieces become more uniform and their surface becomes smoother and brighter, while the cell size
becomes smaller and more uniform. Monoglycerides seem to increase these effects. Sugars modify the
flavor and texture, and may help to control shape and size of tough doughs.
Alternative puffing methods- Puffing processes depending on contact of dough pieces with very hot
embossed cylinders are in current use. Roll temperatures of 350° to 800°F are said to be within the
practical range, and it is likely that most producers employ temperatures in the upper half of this
range. Rolls may be heated by radiant (infrared) energy or by the circulation of high temperature fluid
media inside the cylinder. In one process (Huber 1955), the dough has a moisture content of 8 to 18%
going into the rolls and 6 -to 7% after puffing. Doughs may be preheated to temperatures below the
boiling point, this technique allowing lower rose temperatures to be used.
Sugar-coated Products
Items which are approximately spherical or disc-shaped, such as puffed wheat and puffed rice,
can be coated by a technique very similar to the pan-coating process used in confectionery
manufacture. The usual apparatus somewhat resembles a cement mixer in having an open bowl
rotating about an axis inclined slightly from the horizontal. The very dry cereal particles are placed in
the bowl and, as it rotates, molten (250°F) sugar syrup is slowly dripped on the bowl's contents. A
small amount of coconut oil may be added to decrease foaming of the sugar syrup and to promote
separation of the coated particles. The tumbling action of the particles results in each of them
remaining separate and becoming uniformly coated with a thin glaze of sugar which hardens upon
cooling. From 25 to 60% of the weight of the finished product is glaze. A stream of hot air is usually
directed into the coating reel to assist in removal of moisture. Some authorities have suggested a syrup
formula of 86% sucrose, 13% corn syrup, and 1% salt. Sometimes 0.01 to 0.05% sodium acetate may
be added to prevent crystallization of the coating.
SNACK FOODS
INTRODUCTION
One dictionary defines a snack as "a slight, hasty repast," while another says it is "a mere bits
or morsel of food, as contrasted with a regular meal; a light or incidental repast." Possibly, neither of
these definitions satisfactorily represents current usage. I have not found "snack food" in any
dictionary, but it is likely that most people would recognize a snack food as being something
consumed primarily for pleasure rather than for social or nutritive purposes and not ordinarily used in
a regular meal. Some foods are used both as snacks and as meal components, pizza being an obvious
example. Snack foods can be either sweet or savory/salty--cookies or crackers, doughnuts or pretzels.
This chapter will deal with those products which are clearly definable as snack foods and which are
not discussed elsewhere in the book-most snacks made by traditional bakery methods will be covered
in the chapter devoted to bakery processing. Only snacks composed in large part of cereals will be
included; this rules out such things as meat snacks (e.g., jerky, sausage sticks), fruit snacks (e.g., fruit
“leathern”), and most confectionery (e.g., chocolates, boiled sweets).
The main subdivisions of this chapter are Popcorn, Formulated Puffed Snacks, and Other
Snacks. To avoid repetition, many details about non-cereal raw materials which have been discussed
previously have been omitted, and it will occasionally be necessary for the reader to refer to other
chapters for details on certain raw materials and equipment.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 149 of 162
POPCORN
Popcorn is unique among grains in that a high degree of expansion can be achieved when it is
heated at atmospheric pressure. Other grains must be superheated in pressurized vessels and then
suddenly transferred to a region of lower pressure if much expansion is to be obtained. Popcorn
evidently behaves as it does because of the physical structure of the entire kernel and the microscopic
structure of the endosperm; characteristics of the starch undoubtedly have an effect.
It should not be necessary to emphasize the commercial importance of popcorn and the snacks
derived from it. The crisp texture, fluffy white appearance, and convenient piece size of popped
corn provide an almost unique combination of properties that can be utilized to advantage in many
different types of snack products. When the ease of processing and the relative cheapness of the raw
material are also considered, the widespread use and acceptance of popcorn snacks can be readily
understood.
Popcorn does have a number of disadvantages, however. Among them are its fragility, its
nonuniformity, and its unfavorable response to adverse environmental influences such as high
humidity.
Some specialized terms used in the popcorn trade should be defined in order to avoid
misunderstandings.
·Popped com with a highly irregular pronged appearance is know as the "butterfly"
type,
·While kernels that are predominantly spheroidal with relatively few projections are
called "mushroom" or "ball" varieties.
·Sometimes the popped kernels are called "flakes."
Four Types of Popcorn
Trade buyers recognize four major types of popcorn:
(1) White hull- less, primarily used for home popping;
(2) Yellow hull-less, which is also sold in kernel form to consumers for home popping, but is used in
large amounts by concessionaires, especially in hot and humid regions, because it retains better texture
at higher moisture contents than other hybrids do;
(3) Large kernel yellow, which is popular for factory popping and the theater trade because it pops
into large flakes with good visual appeal and is resistant to rough handling-it requires more oil than the
other types and becomes tough in the presence of moisture; and
(4) Medium yellow, a compromise having good appearance when popped and reasonably good
texture. It should be understood that there is considerable overlapping of characteristics between the
types. Further details on some of the types will be given in the following paragraphs.
White popcorn is rarely used for commercial production of snacks. This category includes
varieties ranging in size from small kernels up to the size normally associated with the large yellow
varieties. Small kernel size generally leads to the highest-volume popped corn, but fragility of these
kernels leads to excessive crumbling when they are processed on a large scale.
Large kernel yellow hybrids pop out large in size-they have a creamy yellow appearance.
Under the usual popping conditions, a ratio of about 25% mushroom or ball kernels to 75% butterfly
kernels will be observed. Large kernel hybrids are popular with the confectionery industry and for
factory popping because the popped corn resists breaking better than any of the other kinds of hybrids.
They do, however, require more oil and humidity-resistant packaging because they get tough and
elastic when they absorb even a small amount of moisture.
Small yellow hull-less popcorn is preferred for consumer preparation because it pops at a
relatively low temperature and has superior eating quality. It has also been widely used in low-volume
on-premises outlets in the South and Southeast, where the consumer requires corn that is tender and
palatable under a wide variety of atmospheric conditions. This type of corn will remain acceptable at
higher moisture content than any of the other hybrids. Its main disadvantages are small size of the
popped kernels and its high degree of fragility.
e-- [email protected] Page 149 of 162
POPCORN
Popcorn is unique among grains in that a high degree of expansion can be achieved when it is
heated at atmospheric pressure. Other grains must be superheated in pressurized vessels and then
suddenly transferred to a region of lower pressure if much expansion is to be obtained. Popcorn
evidently behaves as it does because of the physical structure of the entire kernel and the microscopic
structure of the endosperm; characteristics of the starch undoubtedly have an effect.
It should not be necessary to emphasize the commercial importance of popcorn and the snacks
derived from it. The crisp texture, fluffy white appearance, and convenient piece size of popped
corn provide an almost unique combination of properties that can be utilized to advantage in many
different types of snack products. When the ease of processing and the relative cheapness of the raw
material are also considered, the widespread use and acceptance of popcorn snacks can be readily
understood.
Popcorn does have a number of disadvantages, however. Among them are its fragility, its
nonuniformity, and its unfavorable response to adverse environmental influences such as high
humidity.
Some specialized terms used in the popcorn trade should be defined in order to avoid
misunderstandings.
·Popped com with a highly irregular pronged appearance is know as the "butterfly"
type,
·While kernels that are predominantly spheroidal with relatively few projections are
called "mushroom" or "ball" varieties.
·Sometimes the popped kernels are called "flakes."
Four Types of Popcorn
Trade buyers recognize four major types of popcorn:
(1) White hull- less, primarily used for home popping;
(2) Yellow hull-less, which is also sold in kernel form to consumers for home popping, but is used in
large amounts by concessionaires, especially in hot and humid regions, because it retains better texture
at higher moisture contents than other hybrids do;
(3) Large kernel yellow, which is popular for factory popping and the theater trade because it pops
into large flakes with good visual appeal and is resistant to rough handling-it requires more oil than the
other types and becomes tough in the presence of moisture; and
(4) Medium yellow, a compromise having good appearance when popped and reasonably good
texture. It should be understood that there is considerable overlapping of characteristics between the
types. Further details on some of the types will be given in the following paragraphs.
White popcorn is rarely used for commercial production of snacks. This category includes
varieties ranging in size from small kernels up to the size normally associated with the large yellow
varieties. Small kernel size generally leads to the highest-volume popped corn, but fragility of these
kernels leads to excessive crumbling when they are processed on a large scale.
Large kernel yellow hybrids pop out large in size-they have a creamy yellow appearance.
Under the usual popping conditions, a ratio of about 25% mushroom or ball kernels to 75% butterfly
kernels will be observed. Large kernel hybrids are popular with the confectionery industry and for
factory popping because the popped corn resists breaking better than any of the other kinds of hybrids.
They do, however, require more oil and humidity-resistant packaging because they get tough and
elastic when they absorb even a small amount of moisture.
Small yellow hull-less popcorn is preferred for consumer preparation because it pops at a
relatively low temperature and has superior eating quality. It has also been widely used in low-volume
on-premises outlets in the South and Southeast, where the consumer requires corn that is tender and
palatable under a wide variety of atmospheric conditions. This type of corn will remain acceptable at
higher moisture content than any of the other hybrids. Its main disadvantages are small size of the
popped kernels and its high degree of fragility.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 150 of 162
Medium-kernel yellow was developed as a compromise between the yellow hulless and the
large yellow hybrids. In appearance and response to moisture uptake it occupies an intermediate level
between the last two types mentioned above. It will form a reasonably high percentage of mushrooms
when popped-not as many as a good large-kernel hybrid but enough to make good caramel corn and
cheese com with only moderate breakage.
Mechanism of Popping
The endosperms of different types of grains show different degrees of starch granule
gelatinization when the kernels are expanded by Popping.
In barley and wheat, which do not expand much, some starch granules undergo complete
gelatinization without apparent expansion while other gelatinized granules expand and fuse. Localized
cell-wall rupturing occurs when these kernels split open, and a few intracellular voids or enlarged
bubbles can be seen in the gelatinized starch granules as a result of the explosion.
Ungelatinized and partly gelatinized starch granules predominate immediately below the
aleurone layer and near the scutellum.
Localized cell-wall rupturing also occurs in the expanded endosperms of popped grain
sorghum, popcorn, and dent corn, but the spongy expanded endosperms consist of intact cells within
which the gelatinized starch granules form a characteristic structure of "soap bubble" appearance, each
bubble representing a starch granule.
The cell walls are not destroyed and remain clearly identifiable except where wall rupturing
contributes to both expansion and formation of voids. The starch granules are not exploded but are
gelatinized and dried into a three-dimensional network or reticulum surrounding empty spaces.
Expansion is much less pronounced in dent corn than in popcorn and sorghum, in which more
cell rupturing occurs to form voids. The soap bubble type of structure is less intensively developed in
all poorly popped kernels. Some unaltered and partly gelatinized starch granules are also present
immediately below the aleurone and near the scutellum even in fully popped kernels.
Quality factors
There are no specific Federal regulations or standards which restrict the contents or claims for
popcorn. If the package is transparent, some decisions can be made on the basis of appearance-the
color of the com, the kernel size, any broken kernels which are present, and the amount of loose
debris. There is no guide to the moisture content of the corn, which is a strong determinant of popping
performance and which must be highly variable considering the kind of packaging used for the retail
packs. No doubt a great deal of consumer dissatisfaction exists with respect to the results obtained
from retail packed popcorn.
Large purchasers can establish specifications and make at least some simple tests to insure a
minimal level of quality. It takes very little time and labor to conduct a pilot plant test of
representative samples presented by prospective suppliers and to verify the quality of deliveries by the
same means.
The consumer is primarily interested in price, flavor, appearance, and texture. Flavor is
strongly influenced by the butter or oil used as a topping, and by the salt. In discussions of popcorn
quality in the literature, flavor is rarely mentioned. Yet, freshly popped corn does have a distinctive
and appealing flavor. This soon dissipates, and most prepared commercial products provide a very
bland base for the oil and salt. So, in home-popped com which is consumed soon after preparation,
favor is a major quality factor, while it is much less important in commercial popcorn where texture
and appearance are the main quality factors arising from the corn itself.
Texture is strongly related to the intrinsic specific volume of the popped kernel, which may be
quite different from the apparent specific volume, the latter being much affected by the shape of the
kernel. Texture also reflects in part the presence of hard particles, i.e., the parts of the hulls which
remain attached to the puffed grain. In addition, the moisture content of the popped corn at the
moment of consumption has a direct effect on the texture. Popped com continues to evolve moisture
until it cools down, but its low water activity causes it to absorb moisture from air of moderate relative
humidity. Even a small rise in the moisture content causes the kernel to become tough and
flexible, and so the popped corn loses much of its appeal.
e-- [email protected] Page 150 of 162
Medium-kernel yellow was developed as a compromise between the yellow hulless and the
large yellow hybrids. In appearance and response to moisture uptake it occupies an intermediate level
between the last two types mentioned above. It will form a reasonably high percentage of mushrooms
when popped-not as many as a good large-kernel hybrid but enough to make good caramel corn and
cheese com with only moderate breakage.
Mechanism of Popping
The endosperms of different types of grains show different degrees of starch granule
gelatinization when the kernels are expanded by Popping.
In barley and wheat, which do not expand much, some starch granules undergo complete
gelatinization without apparent expansion while other gelatinized granules expand and fuse. Localized
cell-wall rupturing occurs when these kernels split open, and a few intracellular voids or enlarged
bubbles can be seen in the gelatinized starch granules as a result of the explosion.
Ungelatinized and partly gelatinized starch granules predominate immediately below the
aleurone layer and near the scutellum.
Localized cell-wall rupturing also occurs in the expanded endosperms of popped grain
sorghum, popcorn, and dent corn, but the spongy expanded endosperms consist of intact cells within
which the gelatinized starch granules form a characteristic structure of "soap bubble" appearance, each
bubble representing a starch granule.
The cell walls are not destroyed and remain clearly identifiable except where wall rupturing
contributes to both expansion and formation of voids. The starch granules are not exploded but are
gelatinized and dried into a three-dimensional network or reticulum surrounding empty spaces.
Expansion is much less pronounced in dent corn than in popcorn and sorghum, in which more
cell rupturing occurs to form voids. The soap bubble type of structure is less intensively developed in
all poorly popped kernels. Some unaltered and partly gelatinized starch granules are also present
immediately below the aleurone and near the scutellum even in fully popped kernels.
Quality factors
There are no specific Federal regulations or standards which restrict the contents or claims for
popcorn. If the package is transparent, some decisions can be made on the basis of appearance-the
color of the com, the kernel size, any broken kernels which are present, and the amount of loose
debris. There is no guide to the moisture content of the corn, which is a strong determinant of popping
performance and which must be highly variable considering the kind of packaging used for the retail
packs. No doubt a great deal of consumer dissatisfaction exists with respect to the results obtained
from retail packed popcorn.
Large purchasers can establish specifications and make at least some simple tests to insure a
minimal level of quality. It takes very little time and labor to conduct a pilot plant test of
representative samples presented by prospective suppliers and to verify the quality of deliveries by the
same means.
The consumer is primarily interested in price, flavor, appearance, and texture. Flavor is
strongly influenced by the butter or oil used as a topping, and by the salt. In discussions of popcorn
quality in the literature, flavor is rarely mentioned. Yet, freshly popped corn does have a distinctive
and appealing flavor. This soon dissipates, and most prepared commercial products provide a very
bland base for the oil and salt. So, in home-popped com which is consumed soon after preparation,
favor is a major quality factor, while it is much less important in commercial popcorn where texture
and appearance are the main quality factors arising from the corn itself.
Texture is strongly related to the intrinsic specific volume of the popped kernel, which may be
quite different from the apparent specific volume, the latter being much affected by the shape of the
kernel. Texture also reflects in part the presence of hard particles, i.e., the parts of the hulls which
remain attached to the puffed grain. In addition, the moisture content of the popped corn at the
moment of consumption has a direct effect on the texture. Popped com continues to evolve moisture
until it cools down, but its low water activity causes it to absorb moisture from air of moderate relative
humidity. Even a small rise in the moisture content causes the kernel to become tough and
flexible, and so the popped corn loses much of its appeal.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 151 of 162
Although commercial distributors of popcorn claim that they consider the kernel texture,
flavor, and other subjective characteristics in evaluating the quality of lots offered to them, the chief
basis for judging popcorn desirability has always been the relative amount of kernel expansion
that is obtained when the com is popped. The percentage of non-popping kernel is a factor in this test.
This is an understandable tendency, since expansion is closely related to the price received by the
processor. Popped com is usually sold and bought by the consumer (in convenience stores, amusement
parks, theaters, etc.) on the basis of volume rather than weight. The concessionaire must fill a bag or
box of given volume with popped com, regardless of whether the raw popcorn is of high or low
expansion. Naturally, the concessionaire prefers a corn of higher expansion since fewer pounds of raw
material will fill the required number of containers. Furthermore, corn of higher expansion potential
generally has a more tender texture than does corn of lower expansion.
Vendors of popcorn must also be concerned with "eatability." This factor is related to
expansion to some extent. The eatability, which could be, roughly defined as the taste satisfaction
experienced by the consumer, is dependent on such qualities as flavor, tenderness, and uniformity of
the popped kernels as well as on the proportion of oil, salt, and other adjuncts applied to the product.
Moisture content of the kernel has a pronounced effect on popping behavior. Kernels that are
too dry pop feebly, giving off a somewhat muffled sound; the kernel often splits partly open and the
unpopped area appears rather dark or scorched. Corn that is too moist pops with a loud explosion
but the expanded kernels are small, rough, jagged, and tough. It was found that oil popped
kernels achieved maximum volume (cubic cm per g dry matter) when the raw corn was at a moisture
content of 13.54%, while air popped corn achieved maximum volume at 14.03%.
The hull is the outer covering or pericarp of the corn kernel. It varies considerably in thickness
among the different varieties, but no variety is completely free of hull, even though some types have
been described as hull-less. Generally, the larger the kernel, the thicker the pericarp. The hull is torn
and fragmented when the kernel violently expands, and some of it is dislodged from the corn, but most
of it remains. In addition to the undesirable appearance contributed by clinging hull fragments, the
texture of the popped kernel is adversely affected-the hulls "get between the teeth" is a common
complaint. Light-colored pericarp is much less noticeable and, if it is also very thin, the hull-less
condition may appear on cursory inspection to have been achieved.
Shape of the popped kernel is affected by variety, moisture content and popping conditions.
Corn yielding a round or ball shape is called the mushroom type, whereas kernels yielding a highly
irregular pronged shape are known as butterfly type. All, or nearly all, types will yield kernels which
have some of both characteristics.
Kernels having the mushroom configuration are preferred by manufacturers of coated or
flavored popcorn because they break up less during the mixing operation and accept a more even
coating of syrup.
On the other hand, butterfly corn has a lower apparent bulk density and retains salt well. In
most cases, its texture is also considered superior to that of mushroom-type corn. For these reasons, it
is procured by the majority of on-site poppers, such as theater concessionaires.
Processing
Popcorn is commercially popped by either the dry method or the wet method. Home popping
can also be performed by either of these two methods and by microwave heating.
Home popping usually is wet popping, a method in which some sort of vegetable oil is used as
a heat transfer medium, but perforated baskets for dry popping over an open fire have been in use ever
since colonial times. Commercial poppers were originally wet poppers, too, but there are inefficiencies
connected with this process that led to the development of dry- popping equipment. Commercial
popping units have been developed through a series of evolutionary changes from the skillet or kettle
used in home popping to very efficient continuous units that can deliver several hundred pounds per
hour of extremely uniform product.
Commercial poppers.-Although dry poppers predominate in continuous production factories today,
there is still some use of wet-popping equipment. The nature of the wet-popping process requires that
it be a batch-type procedure. A fully automated wet-popping line called the Pop-O-Matic controls
loading, popping, and dumping automatically in accordance with the temperature sequence. The
e-- [email protected] Page 151 of 162
Although commercial distributors of popcorn claim that they consider the kernel texture,
flavor, and other subjective characteristics in evaluating the quality of lots offered to them, the chief
basis for judging popcorn desirability has always been the relative amount of kernel expansion
that is obtained when the com is popped. The percentage of non-popping kernel is a factor in this test.
This is an understandable tendency, since expansion is closely related to the price received by the
processor. Popped com is usually sold and bought by the consumer (in convenience stores, amusement
parks, theaters, etc.) on the basis of volume rather than weight. The concessionaire must fill a bag or
box of given volume with popped com, regardless of whether the raw popcorn is of high or low
expansion. Naturally, the concessionaire prefers a corn of higher expansion since fewer pounds of raw
material will fill the required number of containers. Furthermore, corn of higher expansion potential
generally has a more tender texture than does corn of lower expansion.
Vendors of popcorn must also be concerned with "eatability." This factor is related to
expansion to some extent. The eatability, which could be, roughly defined as the taste satisfaction
experienced by the consumer, is dependent on such qualities as flavor, tenderness, and uniformity of
the popped kernels as well as on the proportion of oil, salt, and other adjuncts applied to the product.
Moisture content of the kernel has a pronounced effect on popping behavior. Kernels that are
too dry pop feebly, giving off a somewhat muffled sound; the kernel often splits partly open and the
unpopped area appears rather dark or scorched. Corn that is too moist pops with a loud explosion
but the expanded kernels are small, rough, jagged, and tough. It was found that oil popped
kernels achieved maximum volume (cubic cm per g dry matter) when the raw corn was at a moisture
content of 13.54%, while air popped corn achieved maximum volume at 14.03%.
The hull is the outer covering or pericarp of the corn kernel. It varies considerably in thickness
among the different varieties, but no variety is completely free of hull, even though some types have
been described as hull-less. Generally, the larger the kernel, the thicker the pericarp. The hull is torn
and fragmented when the kernel violently expands, and some of it is dislodged from the corn, but most
of it remains. In addition to the undesirable appearance contributed by clinging hull fragments, the
texture of the popped kernel is adversely affected-the hulls "get between the teeth" is a common
complaint. Light-colored pericarp is much less noticeable and, if it is also very thin, the hull-less
condition may appear on cursory inspection to have been achieved.
Shape of the popped kernel is affected by variety, moisture content and popping conditions.
Corn yielding a round or ball shape is called the mushroom type, whereas kernels yielding a highly
irregular pronged shape are known as butterfly type. All, or nearly all, types will yield kernels which
have some of both characteristics.
Kernels having the mushroom configuration are preferred by manufacturers of coated or
flavored popcorn because they break up less during the mixing operation and accept a more even
coating of syrup.
On the other hand, butterfly corn has a lower apparent bulk density and retains salt well. In
most cases, its texture is also considered superior to that of mushroom-type corn. For these reasons, it
is procured by the majority of on-site poppers, such as theater concessionaires.
Processing
Popcorn is commercially popped by either the dry method or the wet method. Home popping
can also be performed by either of these two methods and by microwave heating.
Home popping usually is wet popping, a method in which some sort of vegetable oil is used as
a heat transfer medium, but perforated baskets for dry popping over an open fire have been in use ever
since colonial times. Commercial poppers were originally wet poppers, too, but there are inefficiencies
connected with this process that led to the development of dry- popping equipment. Commercial
popping units have been developed through a series of evolutionary changes from the skillet or kettle
used in home popping to very efficient continuous units that can deliver several hundred pounds per
hour of extremely uniform product.
Commercial poppers.-Although dry poppers predominate in continuous production factories today,
there is still some use of wet-popping equipment. The nature of the wet-popping process requires that
it be a batch-type procedure. A fully automated wet-popping line called the Pop-O-Matic controls
loading, popping, and dumping automatically in accordance with the temperature sequence. The
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 152 of 162
complete plant includes a seasoning mixer kettle, a conveyor assembly for moving the popped kernels
to a tumbler where small pieces, unpopped corn, etc., are removed, a blower conveyor, and a remote-
control panel. It accepts a 5-lb charge of com about every three minutes from a hopper holding 400 lb
or more. Seasoning oil and salt are dispensed in measured amounts for each batch, and the quantities
may be changed to suit different formulations.
Another commercial line of straight-line wet-method popping plants consists of conveying
systems, mechanical oil feeder, poppers, and a sifter. The popped corn storage bin is fabricated on-site
to fit the space limitations of the producer's plant. The basic module contains three gas popping units,
and any number of the units can be assembled to give the needed output. The framework of this plant
is reinforced 2-inch tubing covered with baked white enamel. The conveyor is 10-inch wide sanitary
coated belting that travels inside a stainless steel trough attached to the frame, and it is driven by a
one-third horsepower gearhead motor. This system has a positive displacement pump that constantly
recirculated the oil at low pressure past the discharge points, the popping units. The oil charge is
measured automatically in a volumetric tube at each discharge point. A turn of the valve releases a
measured oil charge directly into the kettle. Returning the valve to its original position allows the
volumetric tube to refill in preparation for the next batch.
A third type of wet popping- or "French fry" plant consists of poppers that can be assembled
in a series over a conveyor belt to give semicontinuous operation. The heavy, cast-aluminum kettles
can pop about 3 lb of corn per cycle. Gas is supplied through a ball joint coupling which allows the
kettle to be rotated for dumping the charge. A motorized stirrer is mounted in the cover. Figure 20.2
illustrates a complete small factory for oil popping of corn. Visible in-the photo, in addition to four
poppers, are conveyors, rotary sifting reels, a coating pan, and equipment for malting coating
syrup (Source: Krispy Kist Korn Machine Co.)
Sifters- After the corn is popped, it should be sifted to remove unpopped kernels, small fragments of
popped corn, charred debris, etc. Most firms which manufacture poppers also offer sifters to round out
their line. All popped corn sifters consist of a rotating inclined drum made of wire screen or perforated
metal. Unwanted scrap pieces fall through the screen and are collected in a pan or on a conveyor
underneath the drum. The pattern of the mesh weave and the. size of the openings are critical in
reducing clogging of the sieve by lodged kernels, and they also have an effect on the percentage of
kernels broken down by the tumbling and abrading action of the sifter. A helical metal ribbon is
affixed to the inside of the cylinder to ensure movement of the kernels toward the exit end. Usually,
the rate of rotation is fixed. The steel mesh cylinder may be totally enclosed by a metal housing, or the
top half may be left exposed. Typical throughput is 750 lb per hr.
Coaters- Most popped corn sold through retail outlets is coated with butter-flavored oil and salt. A
considerable amount is sold with cheese- flavored coating. Although it is possible to purchase butter-
flavored oil in drums and spray it on the popcorn without further treatment, the better procedure is to
bring the oil within a temperature range that is optimum for spraying. Not only does this improve
coverage, but it facilitates pumping and metering. Powdered cheese flavors can be mixed with the oil
and the mixture pumped to the coating reel, where it is sprayed on the popped corn. Alternatively, the
cheese-flavored powder can be dispersed into coating reels by various types of feeders. There it
adheres to the liquid oil which has been sprayed on the corn.
Caramel corn factories.-A fairly large percentage of commercially popped com is further processed
into caramel corn of various types. The range in size of these operations is extremely wide, varying
from small retail operations that may produce a few tons of pounds per hour in hand stirred kettles to
fully automated lines putting out thousands of pounds per hour of nationally distributed caramel corn
confections.
FORMUIATED PUFFED SNACKS
It is characteristic of popcorn that the whole kernel is used. Fractured or partial kernels do not
expand well, if at all. As mentioned before, other grains can be puffed by special methods, and
sorghum can be popped fairly well using the simple procedure which is effective for popcorn, but
there is obviously a need for techniques which can make puffed snacks of different shapes, sizes,
e-- [email protected] Page 152 of 162
complete plant includes a seasoning mixer kettle, a conveyor assembly for moving the popped kernels
to a tumbler where small pieces, unpopped corn, etc., are removed, a blower conveyor, and a remote-
control panel. It accepts a 5-lb charge of com about every three minutes from a hopper holding 400 lb
or more. Seasoning oil and salt are dispensed in measured amounts for each batch, and the quantities
may be changed to suit different formulations.
Another commercial line of straight-line wet-method popping plants consists of conveying
systems, mechanical oil feeder, poppers, and a sifter. The popped corn storage bin is fabricated on-site
to fit the space limitations of the producer's plant. The basic module contains three gas popping units,
and any number of the units can be assembled to give the needed output. The framework of this plant
is reinforced 2-inch tubing covered with baked white enamel. The conveyor is 10-inch wide sanitary
coated belting that travels inside a stainless steel trough attached to the frame, and it is driven by a
one-third horsepower gearhead motor. This system has a positive displacement pump that constantly
recirculated the oil at low pressure past the discharge points, the popping units. The oil charge is
measured automatically in a volumetric tube at each discharge point. A turn of the valve releases a
measured oil charge directly into the kettle. Returning the valve to its original position allows the
volumetric tube to refill in preparation for the next batch.
A third type of wet popping- or "French fry" plant consists of poppers that can be assembled
in a series over a conveyor belt to give semicontinuous operation. The heavy, cast-aluminum kettles
can pop about 3 lb of corn per cycle. Gas is supplied through a ball joint coupling which allows the
kettle to be rotated for dumping the charge. A motorized stirrer is mounted in the cover. Figure 20.2
illustrates a complete small factory for oil popping of corn. Visible in-the photo, in addition to four
poppers, are conveyors, rotary sifting reels, a coating pan, and equipment for malting coating
syrup (Source: Krispy Kist Korn Machine Co.)
Sifters- After the corn is popped, it should be sifted to remove unpopped kernels, small fragments of
popped corn, charred debris, etc. Most firms which manufacture poppers also offer sifters to round out
their line. All popped corn sifters consist of a rotating inclined drum made of wire screen or perforated
metal. Unwanted scrap pieces fall through the screen and are collected in a pan or on a conveyor
underneath the drum. The pattern of the mesh weave and the. size of the openings are critical in
reducing clogging of the sieve by lodged kernels, and they also have an effect on the percentage of
kernels broken down by the tumbling and abrading action of the sifter. A helical metal ribbon is
affixed to the inside of the cylinder to ensure movement of the kernels toward the exit end. Usually,
the rate of rotation is fixed. The steel mesh cylinder may be totally enclosed by a metal housing, or the
top half may be left exposed. Typical throughput is 750 lb per hr.
Coaters- Most popped corn sold through retail outlets is coated with butter-flavored oil and salt. A
considerable amount is sold with cheese- flavored coating. Although it is possible to purchase butter-
flavored oil in drums and spray it on the popcorn without further treatment, the better procedure is to
bring the oil within a temperature range that is optimum for spraying. Not only does this improve
coverage, but it facilitates pumping and metering. Powdered cheese flavors can be mixed with the oil
and the mixture pumped to the coating reel, where it is sprayed on the popped corn. Alternatively, the
cheese-flavored powder can be dispersed into coating reels by various types of feeders. There it
adheres to the liquid oil which has been sprayed on the corn.
Caramel corn factories.-A fairly large percentage of commercially popped com is further processed
into caramel corn of various types. The range in size of these operations is extremely wide, varying
from small retail operations that may produce a few tons of pounds per hour in hand stirred kettles to
fully automated lines putting out thousands of pounds per hour of nationally distributed caramel corn
confections.
FORMUIATED PUFFED SNACKS
It is characteristic of popcorn that the whole kernel is used. Fractured or partial kernels do not
expand well, if at all. As mentioned before, other grains can be puffed by special methods, and
sorghum can be popped fairly well using the simple procedure which is effective for popcorn, but
there is obviously a need for techniques which can make puffed snacks of different shapes, sizes,
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 153 of 162
colors, flavors, and textures, and can use a variety of flours and meals. This has been achieved, and it
is the purpose of this section to review the technology of the extrusion puffing of meals and doughs.
Other grain products- Large quantities of corn meal are used in puffed, extruded snack products and
in many brands of fried corn chip snacks. The production of corn flour and corn meal by dry milling
operations is discussed in another chapter. Field (dent variety) com is sometimes processed directly
into alkaline-treated masa for use in corn chips based on the traditional tortilla preparation method
(such as "Fritos"). These production methods will be discussed below.
Flour and other derivatives of the wheat kernel are used in many baked, fried, and extruded
snack products, some examples being pretzels, flavored crackers (cheese, etc.), and cookies. Flour,
bran, farina, and other fractions of the wheat kernel are obtained by means of the milling process,
which is a combination of conditioning, grinding, and particle-classification operations.
Flours from hard wheat are used as ingredients for such products as bread, rolls, pretzels,
English muffins, etc. Doughs made from soft wheat flours tend to require smaller quantities of water
in their preparation and to be soft and less elastic. Soft wheat flour is used mainly for cakes, cookies,
and quick breads such as baking powder biscuits and cake-type muffins.
Expandable ingredients.-Many types of starchy flours and meals obtained from grains, tubers, etc.,
have been found to be suitable ingredients for puffed snacks.
Rice flour expands readily into a low-density, white, and bland tasting product of crisp but
rather fragile texture.
Corn meals can be expanded with little difficulty into crisp pieces having the typical corn
flavor and a color that is white or light yellow according to the type of com.
Fats, Oils, Emulsifiers and Antioxidants
The ingredients described in this section are included here because they are used in the
preparation of snack products. Other materials of the same type are discussed in the chapter on bakery
products. Frying fat is both a processing agent (heat transfer medium) and an ingredient in many
important snack products, such as potato chips. In other snacks, it may function only as an ingredient.
In any case, it has significant effects on the appearance, flavor, and texture of the product and is often
the ingredient which limits shelf-life. It may also be the most expensive ingredient in the product.
Major sources of food lipids are annual field crops of soybeans, peanuts, cottonseed, rapeseed
("canola"), corn, and sunflower seed. Animal fats, including butter, lard, tallow, and grease, are very
important snack ingredients. Palm, palm kernel, coconut, and olive oils are food oils originating from
trees grown almost entirely in the tropics. Cocoa butter is an expensive but highly important fat in
confectionery manufacture.
Shortenings.-The shortenings used in some snacks include animal fats and oils and vegetable fats and
oils. The animal products in use are butter, beef fats, and a few other minor items. Vegetable
shortenings are based on many different kinds of fats and oils from seeds, fruits, and nuts.
Since butter is quite expensive relative to most other fats, its use is restricted to those products
in which its flavor makes a significant contribution to acceptability or in which its use permits
advertising claims having marketing value. Popcorn is traditionally seasoned with butter, but virtually
all commercially popped com of the "buttered" variety will contain vegetable oil materials with added
artificial or natural butter flavors. If some of the natural product is to be included for labeling and
marketing purposes, low-score butter is often preferred to the blander high-score products.
Lard has a distinctive natural flavor that is thought to be desirable in some foods, although it is
not a common ingredient in snacks because of its limited stability.
Beef tallow is obtained from edible fatty tissues of cattle. It is normally a hard but plastic fat
having a melting point of about 110º to 120º F. Because of its hardness, it is often subjected to further
processing rather than used in its native form.
Beef fats rendered by special methods are separated by fractional crystallization into oleo oil
(low melting fraction) and oleostearin (high melting fraction). Its short plastic range (from about 70' to
80'F) and relatively low melting point make oleo oil a fairly good substitute for coconut oil in some
e-- [email protected] Page 153 of 162
colors, flavors, and textures, and can use a variety of flours and meals. This has been achieved, and it
is the purpose of this section to review the technology of the extrusion puffing of meals and doughs.
Other grain products- Large quantities of corn meal are used in puffed, extruded snack products and
in many brands of fried corn chip snacks. The production of corn flour and corn meal by dry milling
operations is discussed in another chapter. Field (dent variety) com is sometimes processed directly
into alkaline-treated masa for use in corn chips based on the traditional tortilla preparation method
(such as "Fritos"). These production methods will be discussed below.
Flour and other derivatives of the wheat kernel are used in many baked, fried, and extruded
snack products, some examples being pretzels, flavored crackers (cheese, etc.), and cookies. Flour,
bran, farina, and other fractions of the wheat kernel are obtained by means of the milling process,
which is a combination of conditioning, grinding, and particle-classification operations.
Flours from hard wheat are used as ingredients for such products as bread, rolls, pretzels,
English muffins, etc. Doughs made from soft wheat flours tend to require smaller quantities of water
in their preparation and to be soft and less elastic. Soft wheat flour is used mainly for cakes, cookies,
and quick breads such as baking powder biscuits and cake-type muffins.
Expandable ingredients.-Many types of starchy flours and meals obtained from grains, tubers, etc.,
have been found to be suitable ingredients for puffed snacks.
Rice flour expands readily into a low-density, white, and bland tasting product of crisp but
rather fragile texture.
Corn meals can be expanded with little difficulty into crisp pieces having the typical corn
flavor and a color that is white or light yellow according to the type of com.
Fats, Oils, Emulsifiers and Antioxidants
The ingredients described in this section are included here because they are used in the
preparation of snack products. Other materials of the same type are discussed in the chapter on bakery
products. Frying fat is both a processing agent (heat transfer medium) and an ingredient in many
important snack products, such as potato chips. In other snacks, it may function only as an ingredient.
In any case, it has significant effects on the appearance, flavor, and texture of the product and is often
the ingredient which limits shelf-life. It may also be the most expensive ingredient in the product.
Major sources of food lipids are annual field crops of soybeans, peanuts, cottonseed, rapeseed
("canola"), corn, and sunflower seed. Animal fats, including butter, lard, tallow, and grease, are very
important snack ingredients. Palm, palm kernel, coconut, and olive oils are food oils originating from
trees grown almost entirely in the tropics. Cocoa butter is an expensive but highly important fat in
confectionery manufacture.
Shortenings.-The shortenings used in some snacks include animal fats and oils and vegetable fats and
oils. The animal products in use are butter, beef fats, and a few other minor items. Vegetable
shortenings are based on many different kinds of fats and oils from seeds, fruits, and nuts.
Since butter is quite expensive relative to most other fats, its use is restricted to those products
in which its flavor makes a significant contribution to acceptability or in which its use permits
advertising claims having marketing value. Popcorn is traditionally seasoned with butter, but virtually
all commercially popped com of the "buttered" variety will contain vegetable oil materials with added
artificial or natural butter flavors. If some of the natural product is to be included for labeling and
marketing purposes, low-score butter is often preferred to the blander high-score products.
Lard has a distinctive natural flavor that is thought to be desirable in some foods, although it is
not a common ingredient in snacks because of its limited stability.
Beef tallow is obtained from edible fatty tissues of cattle. It is normally a hard but plastic fat
having a melting point of about 110º to 120º F. Because of its hardness, it is often subjected to further
processing rather than used in its native form.
Beef fats rendered by special methods are separated by fractional crystallization into oleo oil
(low melting fraction) and oleostearin (high melting fraction). Its short plastic range (from about 70' to
80'F) and relatively low melting point make oleo oil a fairly good substitute for coconut oil in some
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 154 of 162
applications. Use of oleo oil, or a blend of oleo oil and some other fat, as a frying medium was one of
the "secrets" to the unique flavor of McDonald's French fries.
Soybean oil and cottonseed oil are common flying fats and are the principal raw materials for
hydrogenated vegetable oil shortenings.
Cocoa butter is an essential part of pure chocolate coatings and is used in a few other special
formulas. Peanut, corn, and palm oils are less frequently used in snacks.
Olive oil, though an important item of commerce, is probably never used in snacks.
Frying fats- Fats used for flying snack products must have different properties from the fats intended
for use as shortenings or as coatings. Hydrogenated cottonseed oil is a common frying fat, and it is
essentially flavorless.
Fresh fat, as it is received, may not be completely satisfactory for frying because the heat
transfer characteristic, partly a function of viscosity are not optimal for this purpose.
Copper ions greatly accelerate the development of oxidative rancidity, so fats should be
prevented from contacting copper, brass, or bronze utensils or fitments at any time.
Antioxidants-Although there is a great diversity in the composition of snack foods, they all contain
some fat, either added as such or present as a component of another ingredient. All of these fats are
subject to oxidative and hydrolytic rancidity, which can cause the development of objectionable odors
and flavors.
Antioxidants are substances capable of retarding the development of rancidity in foods.
Natural antioxidants can be found in many nonpurified fats, such as cocoa butter, while certain
synthetic chemical compounds can be added to fats for the same purpose.
From a chemical standpoint, rancidity is of two types:
(1) Hydrolytic rancidity, which can lead to the occurrence of -soapy flavors, and
(2) Oxidative rancidity, which causes the pungent or acrid odor characteristic of badly deteriorated
fat.
When hydrolytic rancidity occurs, oxidative rancidity development is facilitated. Oxidative
rancidity is unquestionably the more important of these two mechanisms so far as effects on food
acceptability are concerned. The susceptibility of a fat to oxidation depends to a considerable extent on
the number of unsaturated bonds in the fatty acid moiety. Polyunsaturated fats are very prone to
oxidation, whereas fully saturated fats and oils are much more stable.
Citric or phosphoric acid improves the effectiveness of antioxidants by chelating ions of
copper or iron, but they do not themselves function directly to prevent fat oxidation. These relatively
innocuous substances are very frequently added as part of the antioxidant mixture. It should be noted
that citric acid is not very resistant to high temperatures, as in frying.
In the antioxidant treatment of nuts, tortilla chips, or any other foodstuff subject to oxidative
rancidity, it is important to add the preservative before oxidation begins in the oil phase of the snack.
When added to fresh nuts, the antioxidant is available to terminate the free radicals as they form. The
antioxidant cannot reverse or mask fat oxidation that has already occurred.
Sweeteners
Sweeteners are used in large quantities for glazed popcorn ("caramel corn" and the like) and
some other snacks. The powdery coatings for savory/salty snacks may also contain sweeteners.
Commercial sucrose-refined cane or beet sugar is one of the purest ingredients available to the
food manufacturer. It is truly "natural" in that the chemical form in which it reaches the consumer is
exactly the same chemical form found in the juice of the cane or beet. The composition of the
fractional percentage of nonsucrose material in beet sugar differs slightly from that of cane sugar, but
in practice the two sugars can be used interchangeably.
Cane or beet sugars from various manufacturers do not differ significantly in composition,
although the physical properties (granulation) may vary. Brown sugars and other non-white types can
vary substantially from manufacturer to manufacturer.
The obvious advantages, in many applications, of handling sugar in dissolved form have led to
the extensive distribution of sucrose as syrups.
e-- [email protected] Page 154 of 162
applications. Use of oleo oil, or a blend of oleo oil and some other fat, as a frying medium was one of
the "secrets" to the unique flavor of McDonald's French fries.
Soybean oil and cottonseed oil are common flying fats and are the principal raw materials for
hydrogenated vegetable oil shortenings.
Cocoa butter is an essential part of pure chocolate coatings and is used in a few other special
formulas. Peanut, corn, and palm oils are less frequently used in snacks.
Olive oil, though an important item of commerce, is probably never used in snacks.
Frying fats- Fats used for flying snack products must have different properties from the fats intended
for use as shortenings or as coatings. Hydrogenated cottonseed oil is a common frying fat, and it is
essentially flavorless.
Fresh fat, as it is received, may not be completely satisfactory for frying because the heat
transfer characteristic, partly a function of viscosity are not optimal for this purpose.
Copper ions greatly accelerate the development of oxidative rancidity, so fats should be
prevented from contacting copper, brass, or bronze utensils or fitments at any time.
Antioxidants-Although there is a great diversity in the composition of snack foods, they all contain
some fat, either added as such or present as a component of another ingredient. All of these fats are
subject to oxidative and hydrolytic rancidity, which can cause the development of objectionable odors
and flavors.
Antioxidants are substances capable of retarding the development of rancidity in foods.
Natural antioxidants can be found in many nonpurified fats, such as cocoa butter, while certain
synthetic chemical compounds can be added to fats for the same purpose.
From a chemical standpoint, rancidity is of two types:
(1) Hydrolytic rancidity, which can lead to the occurrence of -soapy flavors, and
(2) Oxidative rancidity, which causes the pungent or acrid odor characteristic of badly deteriorated
fat.
When hydrolytic rancidity occurs, oxidative rancidity development is facilitated. Oxidative
rancidity is unquestionably the more important of these two mechanisms so far as effects on food
acceptability are concerned. The susceptibility of a fat to oxidation depends to a considerable extent on
the number of unsaturated bonds in the fatty acid moiety. Polyunsaturated fats are very prone to
oxidation, whereas fully saturated fats and oils are much more stable.
Citric or phosphoric acid improves the effectiveness of antioxidants by chelating ions of
copper or iron, but they do not themselves function directly to prevent fat oxidation. These relatively
innocuous substances are very frequently added as part of the antioxidant mixture. It should be noted
that citric acid is not very resistant to high temperatures, as in frying.
In the antioxidant treatment of nuts, tortilla chips, or any other foodstuff subject to oxidative
rancidity, it is important to add the preservative before oxidation begins in the oil phase of the snack.
When added to fresh nuts, the antioxidant is available to terminate the free radicals as they form. The
antioxidant cannot reverse or mask fat oxidation that has already occurred.
Sweeteners
Sweeteners are used in large quantities for glazed popcorn ("caramel corn" and the like) and
some other snacks. The powdery coatings for savory/salty snacks may also contain sweeteners.
Commercial sucrose-refined cane or beet sugar is one of the purest ingredients available to the
food manufacturer. It is truly "natural" in that the chemical form in which it reaches the consumer is
exactly the same chemical form found in the juice of the cane or beet. The composition of the
fractional percentage of nonsucrose material in beet sugar differs slightly from that of cane sugar, but
in practice the two sugars can be used interchangeably.
Cane or beet sugars from various manufacturers do not differ significantly in composition,
although the physical properties (granulation) may vary. Brown sugars and other non-white types can
vary substantially from manufacturer to manufacturer.
The obvious advantages, in many applications, of handling sugar in dissolved form have led to
the extensive distribution of sucrose as syrups.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 155 of 162
Corn syrups, which consist of cornstarch hydrolyzed to varying degrees, have the outstanding
advantage of being cheaper, on a solids basis, than refined cane or beet sugar.
Corn syrup solids and dextrose are available for those users who desire a higher concentration
of solids or who do not want to handle the liquid form. As the name suggests, corn syrup solids are
prepared by drying corn syrups. The normal moisture contents of these products lies between 3.0 and
3.5%.
Other Ingredients
Snack food manufacturers procure large quantities of many ingredients not described in the
preceding discussion. To avoid duplication with the Bakery Products sections on ingredients, and
similar discussions elsewhere, these ingredients will not be described here but will be covered by
references to the appropriate article, when necessary.
FACTORS AFFECTING QUALITY OF PUFFED SNACKS
Puffing Behavior of Starches
The use of cereal flours and meals as the major ingredients in puffed snacks has been a natural
result of the low cost and excellent expansion potential of such materials as cornmeal. Snacks made
with cornmeal have a typical flavor which, though not objectionable in it, may not be entirely
compatible with other flavors which may be needed to characterize a new type of snack.
Unmodified cereal starches can be puffed at medium to high temperatures using either steam or
water as moisturizers; they can serve as bland-tasting bases for formulated products such as nutritional
snacks.
Uncooked granular starches are suitable bases for half-products. A simple formula would
include Monoglycerides, color, flavor, and 16% water. The ingredients would be preblended and
processed through a continuous cooker-extruder at 250º to 350º F.
Conditions in the extruder must be sufficiently rigorous to rupture the starch granules. After
cooking, the dough is formed into desired shapes and sizes by any convenient method. As with most
half-products, the dough pieces can be either baked immediately or dried to some lower moisture
content and then deep-fat fried. Depending on the conditions of cooking and expansion and the
amount and type of ingredients, the structure of the collet will vary from low-density, large-cell foam
to a brittle, dense network.
The extent of volume expansion and the texture of the finished snack are influenced by the
amylose: amylopection ratio. Available cornstarches range from high (50-70%) amylose through
regular dent (25-27% amylose) to the waxy maize varieties that are virtually 100% amylopectin.
Sorghum starches with amylopectin contents from 17% to almost 100% are also being offered.
Starches having high amylopectin contents tend to give fragile products of low density.
Some amylose must be present to give adequate resistance to breakage and textures that
are acceptable to the consumer. On the other hand, products containing only com, red milo, and
tapioca starches will be hard in texture and too high in density. The texture can be softened somewhat
by the addition of plasticizers such as sucrose, dextrose, or sorbitol, but normally 50% or more
amylopectin is needed for a good quality product. A starch system containing 5-20% amylose was
suggested as most suitable by Feldberg (1969). In baked-type puffed snacks, pre-extrusion moisture
contents in the range of 20-35% and a starch having 80-100% amylopectin content are necessary to
yield acceptable products.
Effect of Moisture Content
Moisture content of the meal is a critical factor affecting the extrusion temperature, pressure,
and product texture. Moisture contents of 13 to 14% are generally recommended. As feed moisture
increases, extrusion temperature drops and less expansion occurs in the extrudate. Pores in the product
become larger and walls of the pores become thicker. After it is baked, the product is crisper or
crunchier in texture. Low moisture results in a dense and hard product due to incomplete gelatinization
of the starch. Such products are suitable for frying under some conditions.
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Corn syrups, which consist of cornstarch hydrolyzed to varying degrees, have the outstanding
advantage of being cheaper, on a solids basis, than refined cane or beet sugar.
Corn syrup solids and dextrose are available for those users who desire a higher concentration
of solids or who do not want to handle the liquid form. As the name suggests, corn syrup solids are
prepared by drying corn syrups. The normal moisture contents of these products lies between 3.0 and
3.5%.
Other Ingredients
Snack food manufacturers procure large quantities of many ingredients not described in the
preceding discussion. To avoid duplication with the Bakery Products sections on ingredients, and
similar discussions elsewhere, these ingredients will not be described here but will be covered by
references to the appropriate article, when necessary.
FACTORS AFFECTING QUALITY OF PUFFED SNACKS
Puffing Behavior of Starches
The use of cereal flours and meals as the major ingredients in puffed snacks has been a natural
result of the low cost and excellent expansion potential of such materials as cornmeal. Snacks made
with cornmeal have a typical flavor which, though not objectionable in it, may not be entirely
compatible with other flavors which may be needed to characterize a new type of snack.
Unmodified cereal starches can be puffed at medium to high temperatures using either steam or
water as moisturizers; they can serve as bland-tasting bases for formulated products such as nutritional
snacks.
Uncooked granular starches are suitable bases for half-products. A simple formula would
include Monoglycerides, color, flavor, and 16% water. The ingredients would be preblended and
processed through a continuous cooker-extruder at 250º to 350º F.
Conditions in the extruder must be sufficiently rigorous to rupture the starch granules. After
cooking, the dough is formed into desired shapes and sizes by any convenient method. As with most
half-products, the dough pieces can be either baked immediately or dried to some lower moisture
content and then deep-fat fried. Depending on the conditions of cooking and expansion and the
amount and type of ingredients, the structure of the collet will vary from low-density, large-cell foam
to a brittle, dense network.
The extent of volume expansion and the texture of the finished snack are influenced by the
amylose: amylopection ratio. Available cornstarches range from high (50-70%) amylose through
regular dent (25-27% amylose) to the waxy maize varieties that are virtually 100% amylopectin.
Sorghum starches with amylopectin contents from 17% to almost 100% are also being offered.
Starches having high amylopectin contents tend to give fragile products of low density.
Some amylose must be present to give adequate resistance to breakage and textures that
are acceptable to the consumer. On the other hand, products containing only com, red milo, and
tapioca starches will be hard in texture and too high in density. The texture can be softened somewhat
by the addition of plasticizers such as sucrose, dextrose, or sorbitol, but normally 50% or more
amylopectin is needed for a good quality product. A starch system containing 5-20% amylose was
suggested as most suitable by Feldberg (1969). In baked-type puffed snacks, pre-extrusion moisture
contents in the range of 20-35% and a starch having 80-100% amylopectin content are necessary to
yield acceptable products.
Effect of Moisture Content
Moisture content of the meal is a critical factor affecting the extrusion temperature, pressure,
and product texture. Moisture contents of 13 to 14% are generally recommended. As feed moisture
increases, extrusion temperature drops and less expansion occurs in the extrudate. Pores in the product
become larger and walls of the pores become thicker. After it is baked, the product is crisper or
crunchier in texture. Low moisture results in a dense and hard product due to incomplete gelatinization
of the starch. Such products are suitable for frying under some conditions.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 156 of 162
As feed moisture is reduced, extrusion temperature rises, the extrudate expands more, and the
pores get smaller with thinner walls. After baking (i.e., drying), the collet is softer and has less crunch.
Throughput can be increased by decreasing the moisture content of the feed, but this generally
has an adverse effect on product quality.
Moisture should be evenly distributed throughout the meal. Gross non-uniformity can lead to
stratified areas in the collets, to scorched particles, and other product defects. Ideally, any moisture
added as water or aqueous solutions should be allowed to equilibrate throughout the bulk material
before it is fed into the extruder, even though acceptable results can sometimes be obtained by
dripping moisture into the extrusion chamber, particularly if only very small amounts are required.
The product collected from the extruder normally reaches an overall moisture content of about
8%, and this is further reduced to 4% or less in hot air dryers (ovens) or deep-fat fryers.
Effect of pH
Variations in pH of the ingredient mixture that can be expected to result from the usual
combination of cereal flour and tap water seem to have little effect on the extrusion operation or
quality of the finished product. When Cabrera (1978) extruded wheat starch at pH levels between 4.4
and 9.0, the expansion ration remained substantially constant.
Below pH 4.4, expansion is decreased, a phenomenon attributed-to acid hydrolysis of starch
in the extruder barrel. When the pH was between 3.0 and 3.4, extruder throughput and power
consumption were reduced.
At alkaline pH levels, the extrudate became darker.
Added Flavors and Colors
Flavoring materials added to extruder feed stock undergoes significant changes during puffing,
and most of the changes are undesirable.
Volatile flavor components flash off. Interactions and decomposition occur as a result of the
high temperatures. Even when flavor quality does not change, there is nearly always a need to include
much larger quantities of flavor than would be required for ordinary cooked products. There are some
indications that improved results are obtained when encapsulated flavors are used.
In a few cases, the flavoring materials interfere with texture development, this being
particularly true if they introduce fatty substances. The chemical stability and volatility of the flavor
components are the chief determinants of success in this approach. Natural flavoring materials such as
cheese powder have noticeable effects on the texture and amount of expansion.
Extrusion-puffed snacks can be satisfactorily colored with food dyes, in some cases. Between
30 and 600 ppm of FD&C pigments may be required to achieve the desired results. Higher levels often
lead to products that are gaudy and unnatural looking. Colors can be added by a dry-blending process
prior to extrusion.
Fading of colors in extruded and expanded snacks is frequently observed and can be related to
four key factors:
1.Excessive heat,
2.Reaction with various proteins,
3.Reaction with reducing ions such as iron and aluminum, and
4.Reactions with reducing sugars.
There is also a physical cause of fading. The foam structure of puffed snacks causes a
refraction of light, which whitens or lightens the basic color of the material. The smaller the bubbles
(or cells), the lighter the color.
EXTRUDERS AND EXTRUIDING
Types of Extruders
Many kinds of extruders are used in the food industry: sausages, pet foods, pasta, surimi, and
several kinds of bakery products are processed by extrusion processes. These machines may differ in
several respects from the equipment used to make puffed snack foods, but breakfast cereals of certain
e-- [email protected] Page 156 of 162
As feed moisture is reduced, extrusion temperature rises, the extrudate expands more, and the
pores get smaller with thinner walls. After baking (i.e., drying), the collet is softer and has less crunch.
Throughput can be increased by decreasing the moisture content of the feed, but this generally
has an adverse effect on product quality.
Moisture should be evenly distributed throughout the meal. Gross non-uniformity can lead to
stratified areas in the collets, to scorched particles, and other product defects. Ideally, any moisture
added as water or aqueous solutions should be allowed to equilibrate throughout the bulk material
before it is fed into the extruder, even though acceptable results can sometimes be obtained by
dripping moisture into the extrusion chamber, particularly if only very small amounts are required.
The product collected from the extruder normally reaches an overall moisture content of about
8%, and this is further reduced to 4% or less in hot air dryers (ovens) or deep-fat fryers.
Effect of pH
Variations in pH of the ingredient mixture that can be expected to result from the usual
combination of cereal flour and tap water seem to have little effect on the extrusion operation or
quality of the finished product. When Cabrera (1978) extruded wheat starch at pH levels between 4.4
and 9.0, the expansion ration remained substantially constant.
Below pH 4.4, expansion is decreased, a phenomenon attributed-to acid hydrolysis of starch
in the extruder barrel. When the pH was between 3.0 and 3.4, extruder throughput and power
consumption were reduced.
At alkaline pH levels, the extrudate became darker.
Added Flavors and Colors
Flavoring materials added to extruder feed stock undergoes significant changes during puffing,
and most of the changes are undesirable.
Volatile flavor components flash off. Interactions and decomposition occur as a result of the
high temperatures. Even when flavor quality does not change, there is nearly always a need to include
much larger quantities of flavor than would be required for ordinary cooked products. There are some
indications that improved results are obtained when encapsulated flavors are used.
In a few cases, the flavoring materials interfere with texture development, this being
particularly true if they introduce fatty substances. The chemical stability and volatility of the flavor
components are the chief determinants of success in this approach. Natural flavoring materials such as
cheese powder have noticeable effects on the texture and amount of expansion.
Extrusion-puffed snacks can be satisfactorily colored with food dyes, in some cases. Between
30 and 600 ppm of FD&C pigments may be required to achieve the desired results. Higher levels often
lead to products that are gaudy and unnatural looking. Colors can be added by a dry-blending process
prior to extrusion.
Fading of colors in extruded and expanded snacks is frequently observed and can be related to
four key factors:
1.Excessive heat,
2.Reaction with various proteins,
3.Reaction with reducing ions such as iron and aluminum, and
4.Reactions with reducing sugars.
There is also a physical cause of fading. The foam structure of puffed snacks causes a
refraction of light, which whitens or lightens the basic color of the material. The smaller the bubbles
(or cells), the lighter the color.
EXTRUDERS AND EXTRUIDING
Types of Extruders
Many kinds of extruders are used in the food industry: sausages, pet foods, pasta, surimi, and
several kinds of bakery products are processed by extrusion processes. These machines may differ in
several respects from the equipment used to make puffed snack foods, but breakfast cereals of certain
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 157 of 162
types, crisp breads, and croutons are often manufactured by equipment not much different from that
used for some snacks.
Extruders used in processing snack foods can have four functions:
1.Mixing,
2.Cooking,
3.Shaping, and
4.Puffing.
Various combinations of these functions can be performed simultaneously by a single piece of
equipment. Mixing occurs in most extruders except those designed to receive a premixed plug or
cylinder of dough, such as those used to shape corn chips. Even though a plunger is intended primarily
to force a plug of dough through a die, some mixing will occur as the dough slides along the side wall
and flows toward the die orifice.
To achieve good mixing of these extremely viscous materials, however, special agitator
designs are required. If cooking is to be performed, jackets are ordinarily provided to supplement the
heat originating from the work performed on the dough. Shaping or forming is a result of the
configuration of the orifice through which the material is extruded and the relative speeds of the cutoff
knife and the dough strand. The equipment will function as a puffer if the dough temperature is
substantially in process of the boiling point of water when the dough leaves the pressurized chamber.
In most extruder designs, two or more of these functions will be performed simultaneously.
Extruders for snack foods accept either doughs or "an unblended mixture of ingredients at one
end of a generally cylindrical casing, and, while forcing the mass to the opposite end with a generally
helical rotating screw, mix, shear, and pressurize the contents before pushing the mass through one or
more relatively small orifices. The casing (and the screw) may or may not be heated or cooled by
circulating fluids.
Extrusion cookers are composed of several components:
1.A live bin which provides a buffer stock of raw material at &e extruder inlet,
2.A variable speed feeding screw which meters raw material into the extruder barrel at a
predetermined rate,
3.An optional preconditioning cylinder which injects steam and/or water into the powdered
ingredients and allows the mixture to at least partially equilibrate, and
4.The extruder barrel. The extruder barrel consists of the chamber walls, which enclose the
screws and the material as it is being processed, jacketed heads, and rotating screws. The
extruder heads have jackets containing circulating steam, water, or other heat transfer mediums
which permit adjustment of the temperature along the length of the barrel.
Direct or One-stage Puffing
According to Smith (1979), steps that can be taken to affect texture, density, mouth feel,
solubility, and form of extrusion-puffed snacks include the following:
1.The method of feeding and preconditioning of ingredients and mixtures.
2.The method and point of moisture application.
3.Control of temperature and moisture contents of product entering the extruder.
4.Control of temperatures within each extruder section.
5.Control of the point within the extruder where maximum dough viscosity is attained.
6.Control of extrusion speeds.
7.Control of time and temperature relationships within each section of the extruder.
8.Control of the time during which product temperatures are elevated to maximum extrusion
temperatures.
9.Control of final extrusion temperatures.
10.Selection of the shaping and sizing devices.
11.Selection of the type, dwell time, drying temperatures, and velocities within the drier and
cooler and of the finished final product moisture.
12.Point and method of flavor application.
Some of the extrusion conditions which should be considered as possibly affecting the product
are:
e-- [email protected] Page 157 of 162
types, crisp breads, and croutons are often manufactured by equipment not much different from that
used for some snacks.
Extruders used in processing snack foods can have four functions:
1.Mixing,
2.Cooking,
3.Shaping, and
4.Puffing.
Various combinations of these functions can be performed simultaneously by a single piece of
equipment. Mixing occurs in most extruders except those designed to receive a premixed plug or
cylinder of dough, such as those used to shape corn chips. Even though a plunger is intended primarily
to force a plug of dough through a die, some mixing will occur as the dough slides along the side wall
and flows toward the die orifice.
To achieve good mixing of these extremely viscous materials, however, special agitator
designs are required. If cooking is to be performed, jackets are ordinarily provided to supplement the
heat originating from the work performed on the dough. Shaping or forming is a result of the
configuration of the orifice through which the material is extruded and the relative speeds of the cutoff
knife and the dough strand. The equipment will function as a puffer if the dough temperature is
substantially in process of the boiling point of water when the dough leaves the pressurized chamber.
In most extruder designs, two or more of these functions will be performed simultaneously.
Extruders for snack foods accept either doughs or "an unblended mixture of ingredients at one
end of a generally cylindrical casing, and, while forcing the mass to the opposite end with a generally
helical rotating screw, mix, shear, and pressurize the contents before pushing the mass through one or
more relatively small orifices. The casing (and the screw) may or may not be heated or cooled by
circulating fluids.
Extrusion cookers are composed of several components:
1.A live bin which provides a buffer stock of raw material at &e extruder inlet,
2.A variable speed feeding screw which meters raw material into the extruder barrel at a
predetermined rate,
3.An optional preconditioning cylinder which injects steam and/or water into the powdered
ingredients and allows the mixture to at least partially equilibrate, and
4.The extruder barrel. The extruder barrel consists of the chamber walls, which enclose the
screws and the material as it is being processed, jacketed heads, and rotating screws. The
extruder heads have jackets containing circulating steam, water, or other heat transfer mediums
which permit adjustment of the temperature along the length of the barrel.
Direct or One-stage Puffing
According to Smith (1979), steps that can be taken to affect texture, density, mouth feel,
solubility, and form of extrusion-puffed snacks include the following:
1.The method of feeding and preconditioning of ingredients and mixtures.
2.The method and point of moisture application.
3.Control of temperature and moisture contents of product entering the extruder.
4.Control of temperatures within each extruder section.
5.Control of the point within the extruder where maximum dough viscosity is attained.
6.Control of extrusion speeds.
7.Control of time and temperature relationships within each section of the extruder.
8.Control of the time during which product temperatures are elevated to maximum extrusion
temperatures.
9.Control of final extrusion temperatures.
10.Selection of the shaping and sizing devices.
11.Selection of the type, dwell time, drying temperatures, and velocities within the drier and
cooler and of the finished final product moisture.
12.Point and method of flavor application.
Some of the extrusion conditions which should be considered as possibly affecting the product
are:
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 158 of 162
(1) Process parameters. Sufficient time after start-up should be allowed for equilibration of the
extruder before starting an experiment. For reporting feed rates, determinations should be repeated
several times with sample collection during appropriate time intervals. The true measured rate of
rotation of the screw and the temperature of the barrel at different locations should be determined
(2) Some system parameters to be measured:
·Temperature of food during extrusion and location of measuring devices.
·Pressure within the extruder at different locations.
·Temperature and pressure profiles along the extruder.
·Mechanical and thermal energy inputs.
·Torque values.
·Residence times, with distribution curves and values for minimum, median, mean, maximum
residence times and dispersion.
·Viscosity of extrudate in the die channel.
(3) Collection of extruded product and post-extrusion processing:
·Procedure for collecting and sampling of product;
·Packaging and
·Storage arrangements and
·Post-extrusion processing, including, for example, cutting, stretching, flattening between
rollers, drying, toasting, flavoring and packaging.
(4) Experimental design. Of course, the above exhaustive list will be found impractical to follow in
most experimental runs in the average pilot plant.
In these cases, the following list of desirable minimum information for reporting extrusion
cooking experiments was suggested:
1.State make, type, and model of extruder. Supply dimensional drawings of barrel, screws, and
dies.
2.Describe equipment used for measuring temperature and pressure, and its location.
3.List the exact composition of the food mix as percentage of each ingredient.
4.Set down the process parameters including true rate of rotation of the screws, input feed rate,
time allowed for equilibration, temperature of barrel at significant points, and any problems
encountered during extrusion.
5.Report the system parameters, such as temperature of food mix during extrusion, pressure
within the extruder, and residence time distribution.
6.Describe procedure for collecting and sampling extruded products- and any post-extrusion
processing.
COMPLETE PLANTS
As a minimum, a line for producing expanded cornmeal snacks would include a conveyor
feeding ingredients to the extruder, an extruder (sometimes called a collet machine), a conveyor from
the collet machine to the oven, an oven or dryer, a coating device with tumbling conveyor and
auxiliary equipment for applying oil and powder, and whatever packaging device has been selected. A
line suitable for producing 300 pounds per hour of finished cheese curls might include equipment
having the following specifications.
1.For conveying cornmeal to the collet machine, an auger conveyor provided with a 400 lb
hopper and a 0.75 hp motor.
2.Collet machine with a 200 lb per hr input; equipped with a vibrated stainless steel cornmeal
hopper.
3.Die head will be water-cooled with a temperature controller. Cutoff knife will have means for
adjusting speed. One or more die plates must be available.
4.A flighted transfer conveyor to feed the oven. A stainless steel hopper receives the collets from
the extruder and deposits them on a mesh belt with stainless steel side guides. It will be
provided with a distribution plate to insure uniform feeding to the oven intake belt.
5.A 300 lb per hr collet oven consisting of a 4 ft x 10 ft oven box and a 36 inch wide carbon steel
mesh belt with roller-chain edge and stainless steel product guides and equipped with 400,000
e-- [email protected] Page 158 of 162
(1) Process parameters. Sufficient time after start-up should be allowed for equilibration of the
extruder before starting an experiment. For reporting feed rates, determinations should be repeated
several times with sample collection during appropriate time intervals. The true measured rate of
rotation of the screw and the temperature of the barrel at different locations should be determined
(2) Some system parameters to be measured:
·Temperature of food during extrusion and location of measuring devices.
·Pressure within the extruder at different locations.
·Temperature and pressure profiles along the extruder.
·Mechanical and thermal energy inputs.
·Torque values.
·Residence times, with distribution curves and values for minimum, median, mean, maximum
residence times and dispersion.
·Viscosity of extrudate in the die channel.
(3) Collection of extruded product and post-extrusion processing:
·Procedure for collecting and sampling of product;
·Packaging and
·Storage arrangements and
·Post-extrusion processing, including, for example, cutting, stretching, flattening between
rollers, drying, toasting, flavoring and packaging.
(4) Experimental design. Of course, the above exhaustive list will be found impractical to follow in
most experimental runs in the average pilot plant.
In these cases, the following list of desirable minimum information for reporting extrusion
cooking experiments was suggested:
1.State make, type, and model of extruder. Supply dimensional drawings of barrel, screws, and
dies.
2.Describe equipment used for measuring temperature and pressure, and its location.
3.List the exact composition of the food mix as percentage of each ingredient.
4.Set down the process parameters including true rate of rotation of the screws, input feed rate,
time allowed for equilibration, temperature of barrel at significant points, and any problems
encountered during extrusion.
5.Report the system parameters, such as temperature of food mix during extrusion, pressure
within the extruder, and residence time distribution.
6.Describe procedure for collecting and sampling extruded products- and any post-extrusion
processing.
COMPLETE PLANTS
As a minimum, a line for producing expanded cornmeal snacks would include a conveyor
feeding ingredients to the extruder, an extruder (sometimes called a collet machine), a conveyor from
the collet machine to the oven, an oven or dryer, a coating device with tumbling conveyor and
auxiliary equipment for applying oil and powder, and whatever packaging device has been selected. A
line suitable for producing 300 pounds per hour of finished cheese curls might include equipment
having the following specifications.
1.For conveying cornmeal to the collet machine, an auger conveyor provided with a 400 lb
hopper and a 0.75 hp motor.
2.Collet machine with a 200 lb per hr input; equipped with a vibrated stainless steel cornmeal
hopper.
3.Die head will be water-cooled with a temperature controller. Cutoff knife will have means for
adjusting speed. One or more die plates must be available.
4.A flighted transfer conveyor to feed the oven. A stainless steel hopper receives the collets from
the extruder and deposits them on a mesh belt with stainless steel side guides. It will be
provided with a distribution plate to insure uniform feeding to the oven intake belt.
5.A 300 lb per hr collet oven consisting of a 4 ft x 10 ft oven box and a 36 inch wide carbon steel
mesh belt with roller-chain edge and stainless steel product guides and equipped with 400,000
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 159 of 162
Btu recirculating airflow system incorporating a 1.5 hp fan. Capacity is based on 9% moisture
infeed material, a bulk density of 3.5 lb per ft3 collets piled two inches high on the belt, and a
dwell time of three minutes in the oven.
6.A flighted transfer belt to take the dried collets from the oven to the coating tumbler.
7.A coating tumbler 30 inches in diameter and ten feet long, capable of being rotated at speeds
from 10 rpm 94.5 rpm. The variable speed drive operates from a 0.5 hp motor. Three 1,000
watt calrod heaters with reflectors can be used to provide heat control within the tumbler.
8.Two jacketed 80 gallon stainless steel kettles provided with high speed propeller mixers. These
are used to blend the oil other components of the coating mixture.
9.A pumping systems for the oil and cheese mixture. This unit generally includes a gear-type
pump with a variable speed drive of about 0.25 hp, a spray tube assembly with dual nozzles,
and a piping network from kettles to pump and pump to coater.
10.A salter with steel hopper, vibratory feeder, and warm-air blower. 10. A conveyor with flighted
transfer belt to feed packaging machine.
OTHER SNACKS
Baked Snacks
Salty-savory baked snacks- Several commercial offerings of this kind of food product have been
adaptations of zwiebach or of flatbreads. The product Ry-Krisp, though sometimes positioned as an
alternative or replacement for conventional wheat bread, is thought to be used mostly as a snack.
Saltines in different shapes, and other types of non-sweet biscuits (e.g., cheese biscuits), are promoted
specifically as snacks by some manufacturers.
Croutons, plain and flavored, have had only slight acceptance as snacks. These items can be
made either from cubed bread loaves (yeast- leavened) or as puffed extrudates (not from leavened
doughs).
Pretzels are a well-accepted snack product. They were originally made from yeast leavened
dough, and most of them still are. Pretzels doughs are made very stiff so that they win withstand the
punishment of machining without becoming sticky or misshapen. The sponge is fermented for a
shorter time than cracker sponges, about ten hours on the average; a typical formula might be 100
parts of flour, 50 parts of water, and 0.5 part of compressed yeast. At the dough stage, 400 parts of
strong flour, about 125 parts of water, 6 parts of salt, and up to 15 parts of shortening are added.
Doughs may receive a short proof stage, but are generally made up without additional fermentation
except for floor time. The machining steps, including formation of the pretzel, are handled
automatically in all but a very few small plants.
There are three basic types of forming machines:
1.A small ball is formed into a rod or strand which is grasped at the ends by forming arms which
then manipulate the dough into the desired shape,
2.A sheet of dough is formed, then cut into flat pretzel shapes, which may be allowed to proof to
regain a rounded cross-section, and
3.Dough is extruded through orifices shaped like a pretzel, and cut by knives or wires to give the
individual pieces.
The first type simulates the ancient hand-tying method; the second is mostly used for sweet
pretzel shapes. Nuggets, sticks, rods, and other less complex shapes are generally formed by extruding
dough through a circular orifice and cutting pieces of the desired length.
Sweet baked snacks.-- Most cookies are used as snacks as well as dessert items. Formulas and
processes for making cookies are fully explained in the previously cited book by Matz and Matz
(1978).
e-- [email protected] Page 159 of 162
Btu recirculating airflow system incorporating a 1.5 hp fan. Capacity is based on 9% moisture
infeed material, a bulk density of 3.5 lb per ft3 collets piled two inches high on the belt, and a
dwell time of three minutes in the oven.
6.A flighted transfer belt to take the dried collets from the oven to the coating tumbler.
7.A coating tumbler 30 inches in diameter and ten feet long, capable of being rotated at speeds
from 10 rpm 94.5 rpm. The variable speed drive operates from a 0.5 hp motor. Three 1,000
watt calrod heaters with reflectors can be used to provide heat control within the tumbler.
8.Two jacketed 80 gallon stainless steel kettles provided with high speed propeller mixers. These
are used to blend the oil other components of the coating mixture.
9.A pumping systems for the oil and cheese mixture. This unit generally includes a gear-type
pump with a variable speed drive of about 0.25 hp, a spray tube assembly with dual nozzles,
and a piping network from kettles to pump and pump to coater.
10.A salter with steel hopper, vibratory feeder, and warm-air blower. 10. A conveyor with flighted
transfer belt to feed packaging machine.
OTHER SNACKS
Baked Snacks
Salty-savory baked snacks- Several commercial offerings of this kind of food product have been
adaptations of zwiebach or of flatbreads. The product Ry-Krisp, though sometimes positioned as an
alternative or replacement for conventional wheat bread, is thought to be used mostly as a snack.
Saltines in different shapes, and other types of non-sweet biscuits (e.g., cheese biscuits), are promoted
specifically as snacks by some manufacturers.
Croutons, plain and flavored, have had only slight acceptance as snacks. These items can be
made either from cubed bread loaves (yeast- leavened) or as puffed extrudates (not from leavened
doughs).
Pretzels are a well-accepted snack product. They were originally made from yeast leavened
dough, and most of them still are. Pretzels doughs are made very stiff so that they win withstand the
punishment of machining without becoming sticky or misshapen. The sponge is fermented for a
shorter time than cracker sponges, about ten hours on the average; a typical formula might be 100
parts of flour, 50 parts of water, and 0.5 part of compressed yeast. At the dough stage, 400 parts of
strong flour, about 125 parts of water, 6 parts of salt, and up to 15 parts of shortening are added.
Doughs may receive a short proof stage, but are generally made up without additional fermentation
except for floor time. The machining steps, including formation of the pretzel, are handled
automatically in all but a very few small plants.
There are three basic types of forming machines:
1.A small ball is formed into a rod or strand which is grasped at the ends by forming arms which
then manipulate the dough into the desired shape,
2.A sheet of dough is formed, then cut into flat pretzel shapes, which may be allowed to proof to
regain a rounded cross-section, and
3.Dough is extruded through orifices shaped like a pretzel, and cut by knives or wires to give the
individual pieces.
The first type simulates the ancient hand-tying method; the second is mostly used for sweet
pretzel shapes. Nuggets, sticks, rods, and other less complex shapes are generally formed by extruding
dough through a circular orifice and cutting pieces of the desired length.
Sweet baked snacks.-- Most cookies are used as snacks as well as dessert items. Formulas and
processes for making cookies are fully explained in the previously cited book by Matz and Matz
(1978).
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 160 of 162
It would seem logical to offer toasted croutons with sweet coatings- caramel coating as on popcorn, or
butter and honey glaze to reproduce a familiar breakfast combination. Such a product has apparently
never been marketed.
e-- [email protected] Page 160 of 162
It would seem logical to offer toasted croutons with sweet coatings- caramel coating as on popcorn, or
butter and honey glaze to reproduce a familiar breakfast combination. Such a product has apparently
never been marketed.
Vedpal Yadav, Lecturer in Food Technology, Government Polytechnic, Mandi Adampur, Hisar, Haryana, India-125053.
e-- [email protected] Page 161 of 161
e-- [email protected] Page 161 of 161
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