Controlled atmosphere and modified atmosphere storage

Its about CA and MA storage of food material, beneficial effects of CA & MA etc.

1. Controlled Atmosphere and Modified
Atmosphere Storage
By
Nungleppam Monica
Food Process Engineering
Indian Institute of Technology KharagpurIndian Institute of Technology Kharagpur

2. CONTROL ATMOSPHERE and
MODIFIED ATMOSPHERE
Control atmosphere (CA):
generally refers to decreased O
2
and increased
CO
2
concentrations, by a precise control of the
gas composition.
Modified atmosphere (MA):
is used when the control of the storage
atmosphere is not closely controlled, such as in
plastic film packaging.

3. DIFFERENCE
MA:
Gas composition is modified initially and it changes
dynamically depending on the respiration rate of
produce and permeability of film or storage structure
surrounding the produce
CA:
Gas atmosphere is continuously controlled throughout
the storage period

4. Scrubbers are
used in controlled
atmosphere storage
to absorb the extra
amount gases
present inside the
packaging
material.
Scrubbers

5. Air contains:
21% O
2

0.03% CO
2
.
Modification of the atmosphere:
 O
2
↓
CO
2
↑
Increased the shelf-life of perishable foods

6. Main crop
potatoes
Celery
Lettuces
Carrots
Leeks
Soft fruit
Asparagus
Broccoli
Spinach
Banana
Mushroom
Respiration rate
HighLow
Short
Long
Shelf
Life

7. Minimum O
2
concentration
tolerated(%)

Commodities
0.5 Tree nuts,dried fruits,and vegetables
1.0 Some cultivars of apples and pears,brocolli,mushroom,garlic,onion,most
cutor sliced(minimally processed)fruits and vegetables
2.0 Most cultivars of apples and
pears,kiwifruits,apricot,cherry,nectarine,peach,plum,strawbery,papaya,pi
neapple,olive,cantaloupe,sweet corn,green
bean,celery,lettuce,cabbage,cauliflower.brussels sprouts
3.0 Avocado,persimmon,tomato,pepper,cucumber,artichoke
5.0 Citrus fruits,green pea,asparagus,potato,sweet potato
Table 1: Fruits and Vegetables classified according to their
tolerance to low O
2
concentrations
Fruits and vegetables differ in their tolerance to low O
2
and to
high CO
2
concentrations.

8. Table 2: Fruits and Vegetables classified according to their
tolerance to elevated CO
2
concentrations
Maximum CO
2
concentration
tolerated(%)

Commodities
2 Apple(Golden Delicious),Asian pear,European
pear,apricot,grape,olive,tomato,pepper(sweet),lettuce,endive,Chinese
cabbage,celery,artichoke,sweet potato
5 Apple(most
cultivars),peach,nectarine,plum,orange,avogado,banana,mango,papaya,
kiwifruit,cranberry,pea,pepper(chilli),eggplant,cauliflower,cabbage,Bru
ssels sprouts,radish,carrot
10 Grapefruits,lemon,lime,persimmon,pineapple,cucumber,summer
squash,snap bean,okra,asparagus,broccoli,parsley,leek,green onion,dry
onion,garlic,potato
15 Strawberry,raspberry,blakberry,blueberry,cherry,fig,cantaloupe,sweet
corn,mushroom,spinach,kale,Swiss chard

9. Table 3: Controlled atmosphere conditions for some fruit species
SpeciesBest
Temp.
(°C)
RH(%) O
2
(%) CO
2
(%)Time
Avocado 7 90 2-3 3-10 2 months
Cherry 0 95 3-10 10-12 30 days
Kiwi 0 98 2 4-5 7 months
Nectarine -0.5 95 2 5 50 days
Peach -0.5 95 2 4-5 40 days
Plum 0 95 2 5 45 days

10. Table 4: Controlled atmosphere conditions for some vegetable
species

11. BENEFICIAL EFFECTS OF PROPER
CA STORAGE:
delayed softening and mealiness (apples, pears,
tomatoes),
delayed toughening (asparagus),
chlorophyll retention (apples, pears, leaf vegetables),
insect control- O
2
(< 1%) and/or elevated CO
2
(40 to
60%)

12. BENEFICIAL EFFECTS OF PROPER
CA STORAGE:
inhibition of the browning of cut surface(cut fruits
and vegetables),
better flavour retention (pineapple, cabbage),
reduction of disorders and decay (berries),
Higher nutritional value after storage (vitamin C).

13. DETRIMENTAL EFFECTS OF CA
(above or below optimum composition
for the commodity):
 May cause irregular ripening of fruits (banana, mango,
pear, and tomato, at O
2
below 2%, CO
2
above 5% for >
1 month).
 May cause certain physiological disorders.
 May enhance anaerobic respiration and development
of off-flavors.
 May cause susceptibility to decay.

14. Table 5: Examples of CA injury

15. STORAGE DISORDER
Low O injury
₂
Internal CO injury
₂
(Brown heart)
Low temp. breakdown
External CO injury
₂

16. DISADVANTAGES
It is quite expensive.
Temp. control required.
Different gas composition for each type of product.
Special operation and operator training required.
Once pack opens or leaks the benefits are lost.

17. RECENT DEVELOPMENTS IN CA
STORAGE
Recent improvements include maintaining CA
during transport in refrigerated marine containers.
CA transport of banana permits the harvest at a more
fully-mature stage.
In addition to CA, there is also a continuing increase
in the use of plastic films and MAP.

18. MODIFIED ATMOSPHERE
PACKAGING (MAP)
Modified Atmosphere Packaging (MAP) involves the
modification of the head space gas in a package in
order to prolong the shelf life of the product it
contains.
The greatest use of MAP is for fresh-cut products (to
maintain 2-5% O
2
and 8-12% CO
2
).
It is possible to improve gas control in MAP by
adding absorbers of ethylene, carbon dioxide and
oxygen.

19. O absorber:-
₂
Iron powder is used commercially as
the active ingredient. Ex. FeO, FeO, FeO
₂ ₃ ₃ ₄
CO absorber:-
₂
Lime(freshly hydrated high
calcium lime (Ca(OH)),activated charcoal,
₂
magnesium oxide)
Ethylene absorber:- Potassium permanganate,
builder clay powder, hydrocarbons, silicones

20. TWO TYPES
Active modification
The atmosphere is modified by pulling a slight
vacuum and replacing the packaging atmophere within
the desired gas mixture.
Passive modification
Modification is achieved by respiration of
commodity within the package and depends on the
characteristics of the commodity and the packaging
film.

21. Passive modification
 Product packaged with selected film
Desired atmosphere develops naturally over time
Takes longer to achieve desired atmosphere in package
Active modification
 Displace or remove gases in package
Replace with mix of desired gases and seal
 Better shelf life is achieved with Active Modification

22. CONCLUSIONS
A strong preservation of quality and nutritional value
is demonstrated by CA storage with a lowering of O
2

and an enhancement of the CO
2
concentrations. This
results in:
better quality after storage
a longer storage period
a longer shelf-life period after storage
a higher nutritional value after storage(vitamin C)
 a more environmental friendly storage(no
postharvest chemical treatments against scald are
needed).

23. Thank you