Rennet (Animal Rennet) — Hidden Processing Agent — Is It Vegan?

Vegan status: Not Vegan

Also known as: Calf rennet, Traditional rennet, Chymosin (animal-derived), Rennin

Source

Extracted from the dried stomach lining of young ruminant animals, primarily calves (abomasum). The enzyme complex (predominantly chymosin and pepsin) curdles milk for cheese production.

Used in

Traditional cheese production. Required in many protected designation of origin (PDO) cheeses — Parmigiano-Reggiano, Pecorino Romano, Manchego, Gruyère, and many others mandate the use of animal rennet by their certification rules.

Appears on label: No. Rarely listed on cheese labels. Ingredient lists typically say only 'cheese cultures, salt, enzymes' — 'enzymes' is the catch-all term that may mean animal rennet, microbial rennet, or FPC (fermentation-produced chymosin).

How to avoid

All cheese made with animal rennet is not vegan. Vegan alternatives: nutritional yeast, cashew cheese, coconut oil-based cheese. For traditional cow's-milk cheese with vegetarian rennet options, look for 'suitable for vegetarians' on UK labels — this indicates non-animal rennet was used.

Notes

Animal rennet has been used for cheese-making for at least 7,500 years. The calf must be slaughtered to obtain the abomasum. The global cheese industry has largely shifted to fermentation-produced chymosin (FPC), which replicates the chymosin enzyme without animal slaughter — FPC now accounts for approximately 80% of global rennet usage. However, PDO and artisan cheeses frequently mandate animal rennet.