Question

In summer season a milkman usually adds a very small amount of baking soda to fresh milk

Answer 1

Because it may become bad after some time

Answer 2

Hey dear,

here is your answer,

During summer months the temperature remains high owing to which lactobacillus increases in milk resulting formation of lactic acid, minimizing the basic pH of milk.

This is the reason why a milkman adds baking soda to increase the overall pH of the milk, since baking soda is a base and helps to neutralize the milk in summers.

Hope this helps you