Question

Curdling of milk is a _________ and a desirable change.

Answer 1

• Milk is converted into curd or yogurt by the process of fermentation. Milk consists of globular proteins called casein. The curd forms because of the chemical reaction between the lactic acid bacteria and casein. During fermentation, the bacteria use enzymes to produce energy (ATP) from lactose.
• Since fermentation is occuring, a chemical change is also occuring.
• Therefore curdling of milk is a chemical change.

Curdling of milk is a chemical and a desirable change.