What is rennet?
Rennet is the product used in cheesemaking that coagulates the milk and helps to separate the solid curd from liquid whey. Traditionally, rennet was extracted from the lining of the fourth stomach of young calves and other ruminant animals. Today, however, rennet also refers to a variety of substances made from plants, microbes, or genetically engineered substances that have the same coagulating properties as animal rennet.
How does rennet work?
Rennet contains an enzyme, chymosin, that encourages the casein protein particles in milk to clump together, forming the curd and trapping fats and minerals while releasing moisture, or whey.
Is all cheese made with rennet?
No. Certain soft cheeses – including cream cheese, ricotta, quark, and paneer – are made without rennet. Most cheese, however, uses some form of rennet derived from animals, plants, microbes, or other sources.