Curd is produced by bacterial fermentation of milk. Bacteria involved in curd formation are lactic acid bacteria which include lactobacillus acidophilus, lactis and Streptococcus lactis. These bacterial strains are produced lactic acid which coagulate and partially digest the milk protein at less than 40 degree Celsius temperature. A small amount of curd called inoculum or starter is added to the milk contain millions of lactobacillus bacteria and initiate the curdling of milk. It also also synthesise vitamin B12 in curd which increases its nutritional importance.
Curd is prepared at home according to the number of individuals in a family. For example for a family of 4 person 750 to 1000 ml boiled and cooled down milk in a taken in a container. One day old one teaspoonful card is mixed with milk and shaken for proper distribution. The contents are incubated at room temperature. The curd get prepared after 4 to 5 hours of incubation.
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