Which type of rennet should I use? And how should I use it?
Rennet is an enzyme that helps coagulate milk to create cheese. It comes in both liquid and tablet form. Rennet can be derived either from animals or from plants and microbes for a vegetarian alternative. It is also available in different strengths depending on what kind of cheese you are making. The amount of rennet used is important: too little will not provide enough enzymes to properly coagulate the milk, and too much will add odd flavours and bitterness. So when using a recipe it is very important to know what strength of rennet the recipe is based on, or be able to calculate how much you need. The strength of rennet is expressed as IMCU, which stands for International Milk Clotting Units.
The Urban Cheese Company stocks a range of rennet products. Here are some of the range we have available and their relative strengths:
| Vegetarian | ||
|---|---|---|
| MM Tablets | >65 IMCU | 1 tablet per 4 litres milk |
| MM Liquid | 240 IMCU | 4.2ml per 10 litres milk |
| Calf (Kosha) | ||
| Dilute Renco | 65 IMCU | 15ml per 10 litres milk |
| Full strength | 280 IMCU | 3.6ml per 10 litres milk |
Once you have chosen your rennet and know its strength you need to work out how much to use. This is done by following this simple calculation below:
IMCU of rennet x 0.01 = the amount of milk that will be coagulated by 1ml of rennet
For example:
280 IMCU x 0.01 = 2.8, so 1ml of rennet coagulates 2.8 litres of milk.
For a recipe, divide the amount of milk in the recipe by the amount of milk that will be set by 1ml of your rennet. This will give you the amount of rennet that you will need:
For example:
8 litres of milk ÷ 2.8 (280 IMCU) = 2.86mls of rennet needed for 8 litres of milk
All rennet types must be diluted or dissolved in cool, non- chlorinated water before adding to the milk. Before adding the rennet, start stirring the milk using an up-and-down motion with a slotted spoon. This gets the milk moving so that the rennet mixes in as quickly as possible. Stop stirring briefly and pour the diluted rennet over the slots/holes of the ladle so that it splatters across the surface of the milk, and then continue stirring with the same up-and-down motion. By stirring well, but not in a swirling motion, you are able to mix it in thoroughly and get it to stop moving quickly. This helps ensure that you get an even coagulation. After the rennet has
been added, the milk must sit very still and not be bumped or stirred.
For more cheesemaking advice and products, take a look through our website today!
