Rennet consists of enzymes that enables milk to coagulate more quickly (turning milk into curds). It takes only a tiny amount of rennet to coagulate a batch of cheese.
You can think of adding rennet like ‘flipping on a switch.’
- Before you add rennet you have milk, in which solids are suspended in water, repelling one another (hence the milky look of milk).
- Then you ‘flipped on the switch’ by adding rennet. All of a sudden, the milk solids come together to form a curd.
Before Renneting
After Renneting
Also read: The Amount of Milk Required to Make Cheese
The 3 Commonly Used Types of Rennet
| Animal Rennet | The original rennet! This was originally sourced as a by-product of the butchering process, since a coagulation-causing enzyme happens to be found in the stomach lining of a calf, lamb, or kid. |
| Vegetable Rennet | A coagulation-causing enzyme derived from vegetables. Thistle rennet is historically the most common and still widely used in Portugal today to make Torta-style sheep’s milk cheeses. |
| Microbial Rennet | Microbial is a laboratory-made enzyme, crafted to behave like traditional animal rennet. Many cheeses label ‘vegetarian’ are made using this rennet. |
A common question that people asked: Can I Eat the Rind on Cheese?
Animal Rennet
Chymosin, an enzyme found in the lining of the fourth stomach (abomasum), of young ruminants to help them digest their mother’s milk until they are old enough to eat grass.
This enzyme is then extracted and used in cheesemaking.
Recommended Animal Rennet:
- Liquid Animal Rennet
- 2 oz.
Vegetable Rennet
The vegetable rennet contains enzymes that act similarly to chymosin on casein micelles and produces softer and more acidic curds than animal rennet. It takes longer to coagulate too.
Here are several examples of vegetable rennet:
- Caper leaves
- Lemons
- Fig trees
- Mallow
- Stinging nettles
- Ground ivy
- And members of the thistle family
Recommended Organic Vegetable Rennet:
Microbial Rennet
FPC
(FPC) Fermentation Produced Chymosin is produced by injecting bacteria, fungi, yeast or enzymes with the genetic material (RNA) of chymosin from a calf and fermenting it.
The chymosin that was produced is then purified which makes FPC non-GMO.
In terms of coagulating, FPC works similarly to animal rennet, is more effectively than the real thing, and is less expensive to produce.
Fun fact: 80% of commercial cheese in the U.S. and U.K. is made with FPC.
Rhizomucor miehei (aka Mucor miehei)
A species of fungus that can be used to produce enzymes (that will produce microbial rennet) to coagulate milk.
The Rhizomucor miehei is non-GMO but is NOT quite as effective at coagulating milk as animal rennet or FPC.
It has a tendency to produce bitter taste to the cheese as well.
Recommended Microbial Rennet (Tablet):
- Derived from fungus, microbial rennet is a great vegetarian-friendly source of coagulant
- Tablets are quartered for easy portioning--use 1/4 tablet for a 1 gallon batch.
- Easily make your own mozzarella, ricotta, cheddar, gouda, paneer, etc at home!
- Can be stored at room temperature, or in the freezer to extend shelf life.
- 30-minute mozzarella recipe & usage chart included
How to Avoid GMOs in Your Cheese
A simple way to avoid GMOs is to sought products from small-scale producers using animal rennet.
An easier way is to look for these terms on the label:
- “Certified Organic“,
- “Non-GMO Project Verified” or/and
- “USDA Organic“
Conclusion
When it comes to artisan cheese, check with your cheesemonger – or better yet, sought out a local cheesemaker at your farmers’ market and have a conversation about what they are using and why.
Articles you might be interested:
- 35 Words Every Cheese Lover Should Know (TERMS)
- The History of Cheese 101 (TIMELINE AND FACTS)
- Goat Cheese vs. Cow Cheese (THE DIFFERENCES)
Last update on 2023-06-05 / Affiliate links / Images from Amazon Product Advertising API