Definition: An enzyme used to coagulate milk during the cheesemaking process. Rennet is derived from one of four sources:
- the stomach lining of a young calf (the enzyme rennin is found in the stomach lining of animals because it aids in the digestion of their mother's milk)
- plants (typically thistle)
- microbes in fungus and yeast
- Genetically engineered rennet that imitates animal rennet
