Quiz: Remember the definition of mal de mer?
rennin ren·nin (rěn'ĭn)
A milk-coagulating enzyme found especially in the gastric juice of the fourth stomach of young ruminants, used in making cheeses and junkets. Also called chymosin.
protein-digesting enzyme that curdles milk by transforming caseinogen into insoluble casein; it is found only in the fourth stomach of cud-chewing animals, such as cows. Its action extends the period in which milk is retained in the stomach of the young animal. In animals that lack rennin, milk is coagulated by the action of pepsin (q.v.), as is the case in humans. A commercial form of rennin, rennet, is used in manufacturing cheese and preparing junket.