[SagarikaGhosh]

A variety of foods are produced by fermentation in and around Asia and Africa, but some of the processes are now used worldwide. Fermented foods have traditionally been known for their better flavour, texture and nutritional value. Their high nutritional content led an interest in development of more high yielding strains for obtaining better quality products. Most fermented foods are produced by solid state fermentation.

[/code]Some examples of fermented foods are cheese, idli , dosa, buttermilk etc. Below are the production processes for some of these fermented foods. The basic processes remain the same for these fermented food production but the temperatures and detailed procedures differ from company to company.

Yoghurt
Microorganism: Lactobacillus bulgaricus and Streptococcus thermophilus (1:1 ratio)
1. Add milk with reduced water content ( 15-20%) or standardised yogurt mix (1-2% milk fat)
2. To the mix add a stabilizer
3. Pasteurize the mixture at 95 C for half an hour
4. Homogenese and cool
5. Add starter culture and mix
6. Incubate the mixture at 43 C while maintaining the pH at 4.5
7. Cool and package.

The yoghurt can be stored for upto a month in temperatures around 4-5 C.

Buttermilk
Microoganism: Streptococcus lactis and Streptococcus cremoris, Lecuconostoc cremoris
1. Add standardized milk with 10 % non fat milk solids and 0.5% milk fat
2. Heat treat the standardised milk at 85 C for 30 mins or 88-91 C for 2-5 min
3. Homeogenize and add starter culture
4. Incubate at 22C for 14-16 hr ; pH 4.5
5. Buttermilk will be produced that can be cooled and packaged.

Cheese
Microorganism:
Streptococcus lactis ,Streptococcus cremoris, Lactobacillus lactis for curd formation
Penicillium roquefortii, P. cammebertii for ripening
1. Milk is mixed with bacterial starter culture and calcium ions which produces lactic acid from lactose and lowers the pH to 4.6
2. Rennet digests casein in the milk while lipase digests the lipids.
3. The coagulum is cooked to inactivate rennet.
4. Whey is separated from the curd
5. Salting
6. Protein and lipid hydrolysis
7. The curd is pressed and ripened to produce cheese.