Question

why the taste of milk is sweet and that of curd is sour

Answer 1

milk have a sugar named lactose in it which is sweet. but when it is converted intocurd, lactobacillus bacteria converts the lactose into lactic acid which tastes sour as it is an acid.
Hope it help you

Answer 2

milk have a sugar named lactose in it which is sweet. but when it is converted into curd, lactobacillus bacteria converts the lactose into lactic acid which tastes sour as it is an acid.