Question

Why person touches the warm milk with his finger before adding a little curd to it for setting curd

Answer 1

Curd can only be formed when the milk is lukewarm. If the milk is very hot or not hot then the curd doesn't form properly. So, person touches the warm milk with his finger to test whether the milk is in the right temperature(lukewarm) before adding a little curd to it. 

Answer 2

Answer:

The starter culture, also known as the inoculum is added to curdle the milk. The lactobacillus is a gram-positive, anaerobic bacterium that converts lactose present in the milk to lactic acid and will digest the milk protein known as casein to make the curd.

Explanation: