Rennet

any substance used by the cheesemaker to curdle milk, chiefly the fourth stomach of the calf. Commercial rennet is prepared by the butcher who removes it from the calf, scrapes off all fat, rolls it in salt for a few hours, and then stretches it to dry. When needed, a piece of suitable size is well soaked in tepid whey or water. The liquid obtained is then poured into the milk to produce curd. Rennet depends on gastric juice for its efficacy. See Cheese