A milkman adds a very small amount of baking soda to fresh milk.
(a) Why does he shift the pH of the fresh milk from 6 to slightly alkaline?
(b) Why does this milk take a long time to set as curd?

(A) He changed the fresh milk’s pH from 6 to slightly alkaline to stop the production of lactic acid, which would otherwise cause the milk to turn sour.

(b) Because the pH is initially neutralised by the lactic acid created here before it is reduced to set the milk into curd, this milk takes a long time to curdle.