Firstly, why make cheese? We make it so that we can store milk over a long period of time. But in order to do so, we need to separate the solid part of the milk from the liquid part. And the way to do that is to add rennet to the milk.
The rennet coagulates the milk. Coagulation of milk is the fundamental process of cheesemaking separating the curds ( solid part) from whey ( liquid part). The active principle in rennet is the enzyme rennin also known as chymosin. The rennin or chymosin “sticks” the proteins together forming a latticework using the calcium in the milk. The whey is trapped within the lattice. In order to release the whey, the protein lattice is cut with a knife or a curd cutter.
Different kinds of rennet ( chymosin) are available:
- Animal Rennet. Derived from the stomach of a calf and is the most effective coagulant. Performs better than rennets mentioned below in aging cheese. Available here: Liquid animal rennet
- Vegetable Rennet. Vegetable rennet derives from plants, normally the thistle family. A delicious cheese, Serra da Estrela, is still being made in Portugal utilising the thistle.
- Microbial Rennet. Derives from fungi such as Rhizomucor meihie. Available here: Liquid microbial rennet
- Fermentation Produced Rennet. The most common rennet or chymosin used in factories of today, up to 80%, is obtained from genetically engineering the bovine rennet genes into a fungus or bacteria.
Rennet is supplied in different forms:
- Tablets – as example 1 tablet coagulates 50 liters milk.
- Capsules – as example 1 capsule coagulates 20 liters
- Powder – as example 2gm coagulates 100 liters
- Liquid- as example 4 drops coagulates 1 liter or 25ml coagulates 100 liters
Both the Animal and Microbial Rennet Finest Kind supplies are in liquid form, so much more convenient and accurate than a tablet, capsule or a powder and furthermore, it is not produced utilising genetic engineering(GMO).
Cows supply varying amounts of milk depending on the season. Whether you need rennet for 0.5 liters or for 13.5 liters, one simply measures the required number of drops of liquid rennet, adds them to a little cool water before adding them to the milk. As example, the dosage for hard cheese is two drops for 0.5 liters and 54 drops for 13.5 liters. Accurate and easy. The rennet is conveniently supplied in a dropper bottle. For larger amounts the rennet can be measured with a measuring flask at 25ml per 100 liters milk. What a pleasure to be able to use a quantity of milk for your cheese without wasting the little left over bits. An old cheesemaker from Holland once told me that it is critical that the correct amount of rennet is added as adding too much rennet can give you a softer curd, contrary to what one would expect.
Rennet can be stored for up to a year in the fridge. But do make sure not to store it in the fridge door as it is an enzyme and will loose it strength if shaken each time the door is opened.