Question

how can we show that setting of curd is a chemical change

Answer 1

milk contains lactos.when we set curd from milk it is sour in taste,which shows that curd contains an acid know as lactic acid.thus, it is an irreversible change . hence,it is chemical change

Answer 2

The bacterium called lactobacillus reproduced in milk and converts the sugar lactose found in milk to lactic acid thus forming the curd. Processing of many other food items like cheese, pickle,wine etc make the use of microorganisms.