🧫 Rennet
Also known as: chymosin
An enzyme (chymosin) that curdles milk for cheese.
Rennet is a substance that makes milk curdle into a curd. Cheese is then made from this curd. The main part of rennet is chymosin. In the past it was obtained only from the abomasum, the fourth stomach chamber of young calves. That is where rennet comes from.
How does it work? In milk, the protein casein floats as tiny balls. Chymosin “cuts off” a protective piece from these balls, and they begin to stick together. This makes a firm curd that holds the fat and minerals. The liquid that separates out is whey.
Today most chymosin is made by microbes. They are given the chymosin gene, and they produce exactly the same protein as a calf. In 1990 the US agency FDA approved this method. As of 2017, about 90% of all rennet in the world was made this way. There are other options too: enzymes from moulds and from plants, such as thistle. Cheeses made with these enzymes suit vegetarians. And soft cheeses like paneer are curdled with no enzyme at all, using lemon juice or vinegar.
How it connects to milk
🧫 Rennet → needed for → 🔄 Curdling → gives → 🧀 Cheese → made from → 🥛 Milk
Links
- Needed for
- 🔄 Curdling
Frequently asked questions
What is rennet made from?
Traditionally, from the stomachs of young calves. Today the same enzyme made by microbes is used most often, along with enzymes from moulds and plants.
Is cheese vegetarian?
It depends on the enzyme. If the cheese is made with microbial or plant rennet, it suits vegetarians; this is usually stated on the pack.