rennin /ren″in/ [ME, rennen, to run] , a milk-curdling enzyme that occurs in the gastric juices of infants and is also contained in the rennet produced in the stomach of calves and other ruminants. It is an endopeptidase that converts casein to paracasein and was formerly used extensively as a curdling agent by the cheese industry. An artificially produced microbial rennet rather than the enzyme extracted from rennet in calves is used in half of the cheese produced in the United States and Canada today. Also called chymosin. Should not be confused with renin.
