Question

why only hot milk can be converted into curd?

Answer 1

Warm milk is used for making curd because lactobacillus bacteria do multiplication on this temperature only. Curd is formed from milk by the division of the bacteria Lactobacillus. When small amount of curd is added to warm milk, the bacteria in the curd divides to convert the rest of the milk also into curd. If the curd is not transferred to a cool place, then curd tuns sour because the bacteria continue to multiply and produce more lactic acid. This makes curd sour in taste.