Rennet is a natural enzyme found in mammal stomachs and is used for setting cheese. After adding the rennet, the milk is left for 45 minutes. After this time, the curds separate from the whey and it is possible to cut the curd.
Normally the rennet is extracted from calves’ stomachs but vegetarian rennet is also available. Natural forms can also be found such as in the sap from figs There are two types of rennet: powdered rennet and liquid rennet. Here in Spain, the liquid version is not readily available but the powdered form can be bought in any pharmacy.
How much rennet to use? These are the quantities that I have found to work.
For 5 litres of goat milk, I’ve found that 1/4 teaspoon (1.25ml) is good dissolved with 1 teaspoon of salt in 1 tablespoon of water.
For a firm cheese, I use two drops per 1 litre of milk and for a softer cheese, 1 drop per litre.
The problem of using too much rennet is that the cheese makes your teeth squeak. Information on Internet and on the jar said that a lot less was necessary and so I did an experiment today with a cheese using only half this amount. The result was that the curds weren’t firm enough to be cut and the resulting cheese was a lot more fragile then usual.