Is Rennet vegan?

Key facts

Verdict

Depends on the brand

Category

Dairy-derived

Also listed as

animal rennet, microbial rennet, chymosin

Best swap

Cashew cheese

Why

Rennet curdles milk in cheesemaking. Animal rennet is taken from unweaned calves; microbial and fermentation-produced chymosin are vegetarian but the cheese itself is still dairy, so never vegan.

Swap it for

What is actually in it

Rennet is the enzyme complex that curdles milk into cheese, and its traditional source is the fourth stomach of unweaned calves, slaughtered as part of the veal and dairy industries. The key enzyme, chymosin, snips the kappa-casein protein so milk solids clump into curds. Animal rennet is still mandatory in many protected European cheeses — Parmigiano-Reggiano, Grana Padano, traditional Gorgonzola, Manchego and others must use it by law to carry their PDO name — which is why those cheeses are never even vegetarian. But rennet has three modern alternatives. Microbial rennet uses enzymes from fungi such as Rhizomucor miehei; fermentation-produced chymosin (FPC) is made by microbes carrying the chymosin gene, identical to the calf enzyme but with no animal involved; and true vegetable rennets come from thistles like cardoon (used in traditional Portuguese and Spanish cheeses such as Torta del Caser), nettles and fig sap. Most industrially produced cheese in North America and much of Europe now uses FPC or microbial rennet because it is cheaper and more consistent — so a great deal of ordinary cheese is accidentally vegetarian, though never vegan, since it is still milk. Labels rarely specify: 'rennet' usually means animal, 'microbial rennet', 'vegetable rennet' or 'non-animal rennet' are the friendly terms, and a vegetarian trademark guarantees no calf rennet. For vegans the whole question is moot — cheese is milk — but it matters when reading labels for household members or assessing 'vegetarian' cheese, and thistle-rennet cheeses are a fascinating traditional exception worth knowing.

Label codes to recognise

Rennet — Unspecified coagulant

Usually calf stomach unless stated otherwise

Microbial rennet — Fungal enzyme

Non-animal

Vegetable rennet — Thistle or plant coagulant

Plant

Chymosin (FPC) — Fermentation-produced enzyme

Non-animal, fermentation

Questions people ask