Rennet
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Every diet
Animal rennet comes from a calf; microbial and vegetable rennet do not.
Enzymes from a non-halal-slaughtered animal are a question for the certifier.
Animal rennet is not kosher; microbial rennet is accepted by most authorities.
Fine for most people at normal amounts.
Rules by country
Rennet is an enzyme used in cheesemaking rather than an additive with an E-number, so the regulators assess it as a food processing aid. What matters on a label is the source, and the EU requires the type of coagulant to be declared for many cheeses.
What is it?
Chymosin is the enzyme that cuts kappa-casein at one precise bond, which collapses the casein micelles and lets them form a gel. Calf rennet was the traditional source, because calves are fed milk and their stomachs were the cheapest way to get it. Fermentation makes the same enzyme now, and it is identical in sequence to the calf version, which is why a cheese made with it behaves the same in the vat.
Where it comes from: An enzyme that cuts the protein that holds milk together, which is what turns milk into cheese. Animal rennet comes from the stomach lining of a calf, while microbial rennet and chymosin made by fermentation do the same job.
Why it’s in food
- Cheese making
- Custards
- Cheese snacks
- Renetting casein
Often found in
Also listed as: Rennet, Animal rennet, Microbial rennet, Rennet enzyme, Chymosin, Vegetarian rennet
Health & gut impact
Rennet is broken down during cheesemaking and in the gut, and both animal and microbial versions have a long record of use. Fermentation-made chymosin was reviewed by JECFA and by the FDA and was found safe at the levels used.
JECFA, safety evaluation of rennet and chymosin preparations
Cheese made with animal rennet is not kosher and is usually treated as unsuitable for halal and vegetarian diets, while microbial rennet and vegetarian enzyme coagulants are accepted by most authorities. Because the coagulant is named on many European cheese labels, it can be checked rather than guessed at.
EU Regulation 1169/2011, food information to consumers
What can I use instead?
Ratio: Use the same activity level; it is a drop-in replacement
Best for: Cheese making at home
Related
More enzymes:
Common questions
Is rennet vegan?
Not when it is animal rennet, which is taken from the stomach of a calf. Microbial rennet and fermentation-made chymosin are not derived from an animal, and most mass-market cheeses in the United States now use them. The ingredient list will say which.
Is rennet safe?
Yes. It is a digestive enzyme broken down during cheesemaking, it has been used for centuries, and the fermentation-made version was evaluated by JECFA and the FDA with no safety concern.
Why do some cheese labels say vegetarian rennet?
It tells you the coagulant came from a plant or a microorganism rather than an animal. It is a reassurance for people who avoid animal rennet, and the EU has required the type of coagulant to be declared on many cheeses since 2014.
Is Rennet safe?
Generally safe (88/100). Rennet is an enzyme used in cheesemaking rather than an additive with an E-number, so the regulators assess it as a food processing aid. What matters on a label is the source, and the EU requires the type of coagulant to be declared for many cheeses.
Is Rennet vegan?
Depends. Animal rennet comes from a calf; microbial and vegetable rennet do not.
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Scientific sources & regulatory citations
- JECFA, safety evaluation of rennet and chymosin preparations
- EU Regulation 1169/2011, food information to consumers