Fermentation-Produced Chymosin (FPC) — Hidden Processing Agent — Is It Vegan?
Also known as: Microbial chymosin, Recombinant chymosin, Fermentation rennet, Chymax
Vegan
No animals or animal-derived substances are involved in producing this agent.
Not required on labels
Listed as 'enzymes' or 'rennet' on cheese labels. Indistinguishable from animal rennet in labelling unless explicitly stated as 'vegetarian rennet' or 'microbial rennet'.
Source
Produced by inserting the calf chymosin gene into a microorganism (Aspergillus niger, Kluyveromyces lactis, or E. coli) which then produces the enzyme via fermentation. No animal slaughter required.
Used In
The majority of commercially produced cheese globally. Cheddar, mozzarella, most supermarket cheeses. FPC produces a purer chymosin than animal rennet with more consistent cheese quality.
How to Avoid
No need to avoid — FPC is vegan. UK products using FPC typically carry the 'suitable for vegetarians' label. Cheese itself is not vegan regardless of rennet type, as it is derived from animal milk.
Editorial Notes
FPC is considered vegan by most vegan organisations because no animal is used or harmed in its production. However, the cheese made from FPC-containing milk is still not vegan — the issue is the dairy, not the enzyme. A vegan asking about FPC is usually investigating whether a specific processed food contains animal rennet as an ingredient, not whether they should eat FPC-produced cheese.