Explain the role of microbes in household food products.

Explanation

Microbes in household products: Microbes have been used in different ways by mankind from time immemorial in the preparation of household products. Some of the household products obtained from microbial activity are :
Dairy Products : A number of bacteria like Lactobacillus and some other commonly called Lactic Acid Bacteria (LAB) are used in the preparation of several dairy products.
Lactic acid fermentation: lactic acid causes coagulation of milk protein casein. Milk is converted into products like curd, yoghurt and cheese.
1. Curd: For making curd, milk is boiled and then the temperature of milk is brought to about `40^@C` by keeping it in a cool place. Now a small amount of curd ( the innoculum or starter containing lactobacillus acidophilus ) is added to the milk. The fermention process begins which converts milk suger lactose into lactic acid. The acid coagulates milk protein by partially digesting it so that a thick concentrated curd prepared. Curd is more nutritious than milk as it contains increased quantity of vitamin `B_(12)`.
2. Yoghurt (= Yogurt): It is prepared by curdling milk with the help of Streptococcus thermophilus and Lactobacillus bulgaricans. The temperature is maintained at about `45^@C ` for four hours.
3. Butter Milk: The acidulated liquid left after churning out butter from curd is butter milk .
4. Cheese : It is a protein rich nutritive preparation obtained after fermentation and curding of milk. It consists of milk curd that has separated from liquid part or whey. Depending upon the water content present in milk`//` curd cheese is of three types.
1. Raw cheese. 2. Unripened cheese (cottage cheese), and 3. Ripened cheese.