Fermented Milk Products - different products

Fermented Milk Products - different products

1. Dr. Zanwar S.R. Assistant professor , mgm CFT , gandheli FPT-238 Fermented Milk Products

2. Products Traditional Yoghurt Dahi Shrikhand

3. Introduction Fermented milk products such as, dahi (curd) and lassi (stirred yoghurt)/ chhach (buttermilk) figure prominently in people’s diet. The Bureau of Indian Standards (BIS) specifications for fermented milk products are based on the type of culture used in their preparations . Milk is also fermented to dahi as an intermediate base product in the making of makkhan (cultured butter), ghee, chakka , and shrikhand .

4. Flow diagram of Yoghurt Receiving whole/defatted milk | Standardization (0.5-5% fat, 9-15 %SNF) | Filtration/clarification (35-40°C) | Pre-heating the mix (60°C) | Homogenization (2500psi) | Pasteurization at 85°C/30 min. | Cooling (43-44°C) | Inoculation (2%) | Packaging | Incubation (41-42°C/3 hrs) (0.75%T.A.) | Cooling and storage (5-7°C)

5. YOGHURT Yoghurt is a semi-solid fermented product made from a standardized milk mix by the activity of a symbiotic blend of Streptococcus thermophilus and Lactobacillus delbruekki subsp. Bulgaricus cultures. The fat content in yoghurt may vary from 0 to 5 % and the solids content from 9 to 20 %. In case of yoghurt thermophilic cultures ( Lactobacillus bulgaricus , Streptococcus diacetilactis , and Lactobacillus acidophilus ) are used which improves the flavour of the yoghurt. Yoghurt is highly acidic in taste and has a harsh acidic flavour . So, it is rarely consumed plain.

6. Advantages The cultures found in yoghurt such as Acidophilus are beneficial to the digestive system.   Bifidobacterium is other beneficial bacteria found primarily in the large intestine and these bacteria produce B-vitamins such as B1, B6 and B12 as well as folic acid and some amino acids. Eating yoghurt will help maintain healthy levels of beneficial bacteria in your gastrointestinal tract.

7. Details of Production Whole or partly defatted milk to increase the solids not fat content by 2-3% to a total of approx. 12% . The mix is preheated to 60°C and homogenized single stage at 2000-2500 psi. Sterilizers are frequently added to the mix but are not essential and excessive amounts are to be avoided. The mix is heated in a vat to 85°C, inoculated with 2% bulk starter and stirred briefly to ensure proper mixing. The mix is then packaged, care being taken that the temperature does not fall below 41°C during the filling operation. The time interval between inoculation and filling should not exceed 45 min. Yoghurt is incubated in the package without further agitation at 41-42°C for about 3 hours, till a titratable acidity of 0.75% is reached. It is then placed under refrigeration to cool to 5-7°C; approx. 8 hours are required, at which time the product is ready for distribution. A final acidity of 0.9% is desired in the product.

8. DAHI Indian curd, known as dahi is a well known fermented milk product consumed by large section of the population. Definition : According to PFA rules, dahi or curd is the product from pasteurized or boiled milk by natural or using bacterial culture. Dahi may contain additional cane sugar. It should have the same percentage of fat and solids-not-fat as milk from which it is prepared. Dahi is consumed as a part of daily diet or a refreshing beverage . The Indian Standard (1978) specification for fermented milk products, dahi should have a pleasing flavour and a clean acidic taste, devoid of undesirable flavour , should have firm body and texture and be uniform with negligible whey separation.

9. Characteristics Requirements Sweet dahi Sour dahi Acidity lactic (%wt.)Max. 0.70 1.0 Yeast and mould count per g. Max. 100 100 Coliform Count per g. Max. 10 10 Phophatase test -ve - ve The designation of dahi based on the types of culture used. Designation culture used Sweet dahi Streptococcus lactis single or in combination with S. diacetilactis , species S. cremoris & Leuconostoc Sour dahi Same as above, along with Lactobacillus bulgaricus or Streptococcus thermophilus or both

10. Nutritive Value Dahi has more nutritive value as compared to original milk. Dahi is more palatable, and those who usually do not like drinking milk would consume it readily. Dahi is more easily digested and assimilated than milk. Dahi seems to exert possible therapeutic value in the stomach and during intestinal disorders, due to its content of antibiotics. Uses of Dahi For direct consumption: either as such or with salt/sugar. For the preparation of Chakka and Shrikhand . For the preparation of makkhan . Especially by heart patients since it is low in fat (skim milk dahi ). Misti dahi Misti dahi or sweet curd is an indigenous sweetened fermented milk product popular in the eastern parts of the India, particularly, in the district of West Bengal. Because of its brown colour as a result of caramelization of sugar during heating, it is also called Lal Doi .

11. Flow diagram of Dahi Receiving Milk | Pre-heating (35-40°C) | Filtration/Clarification | Standardization | Pre-heating (60°C) | Pasteurization (80-90°C/15-30 min.) and homogenization | Cooling (22-25°C) | Inoculation (1-3%) | Packaging | Incubation (22-25°C/16-18 hrs) | Cooling and Storage

12. Starter cultures used in manufacture of fermented milk products Product Microorganisms Incubation temp. & time Dahi , Shrikhand , Misthi doi , Lassi , Buttermilk Lactococcus lactis subsp. Lactis , Lactococcus lactis subsp cremoris , Lactococcus lactis subsp. Lactis var. Diacetyllactis 22°C for 12-14 hours or 37°C for 5-8 hours Yoghurt Lactobacillus delbrueckii subsp. Bulgaricus, Streptococcus thermophilus 43-45°C for 3-4 hours

13. SHRIKHAND Shrikhand is semi solid soft, sweetish sour fermented dairy product. It is prepared from cow, buffalo or mixed milk. Lactic fermented curd is obtained by the associative action of microorganisms on the milk constituents. The curd is cut or stirred to expel whey through a muslin cloth. This results in a solid mass known as chakka . The next step in the preparation of shrikhand is mixing chakka with the required amounts of sugar, colour , flavour etc. to get the end product. The composition of the shrikhand depends on the initial composition of the milk, the degree of fermentation, the extent of whey removal and the quality of sugar added.

14. BIS Standards Characteristics Skim Milk Chakka Whole Milk Chakka Shrikhand Total solids % min 20 30 58 Milk fat (%) DM 5 (Max) 33 (Min) 8.5 Milk Protein (%) min on DM 60 37 10.5 Titratable acidity % LA 2.5 2.5 1.4 Total ash (%) Max on DM 5 3.5 0.9 Sugar (%) Max on DM -- -- 72.5 Coliform (per g) Max 10 10 10 Yeast and Mould (per g) Max 20 20 50

15. Method of Manufacture Traditional Method Good quality milk is standardized to 5.0 per cent fat This milk is transferred a kettle / vat / container through a muslin cloth. The milk is heated to boiling and cooled to 30°C. Lactic culture is added at the rate of 0.5 percent of milk and mixed well with the help of a stirrer. The starter culture should preferably be curd from the previous batch. The milk is incubated at 30°C till the desired acidity is attained. The duration of incubation is usually 10-12 hours. After the curd has been properly set and the desired acidity developed, the contents are transferred to another vessel through a clean, wet muslin cloth.

16. The muslin cloth containing the curd is formed in to a bag and hung on a stand to facilitate draining of whey. To achieve the faster expulsion of whey, gentle pressure may be applied. The whey is collected separately in another container. A semi solid mass is obtained after the complete expulsion of whey. This is called as chakka and this is used as an ingredient in the production of shrikhand . The weight of the chakka is measured and is transferred to mixer or blender. Good quality sugar at the rate of 80% of the weight of chakka is added to chakka and it is thoroughly kneaded or mixed either manually or mechanically to a homogeneous consistency. Flavor, color and other additives such as fruits, nuts etc. may be added to enrich the shrikhand depending on the consumers taste. The weight of the product is recorded and it is usually packaged in polystyrene cups and stored under refrigerated condition.

17. Uses Chakka is used for the preparation of shrikhand . Srikhand is either used for direct consumption or preparation of srikhand wadi .