Animal rennet is a complex collection of enzymes that is taken from the stomachs of young ruminant animals such as calves, lambs, and kids (young goats) . The key enzyme in animal rennet, chymosin, causes the casein proteins in milk to stick together and form a solid curd while releasing moisture (whey) and trapping the fats and minerals from the milk that are essential for making cheese. Rennet is used to coagulate milk during cheese making, separating the liquid whey from the solid curd that will eventually become cheese. It is available in liquid, tablet, or powder form, with liquid rennet being easier to measure and more often used for small-batch rennet cheese, while tablet and powder forms have a longer shelf life without needing preservatives.
The traditional source of animal rennet is the stomach lining of calves, which contains chymosin, a naturally occurring enzyme that helps digestion and milk absorption. Rennet is made of enzymes found in the lining of un-weaned mammal stomachs, usually from a cow (calf), sheep (lamb), or goat (kid) . It is important to note that animal rennet is not vegetarian, and there are alternative rennets available, such as vegetable rennet, microbial rennet, or fermentation-produced chymosin, which are in varying degrees acceptable to vegetarians.
In summary, animal rennet is a crucial component in the cheese-making process, as it helps coagulate milk and separate the whey from the curd, ultimately leading to the production of cheese. It is derived from the stomach lining of young ruminant animals and contains enzymes that play a key role in the transformation of milk into cheese.
