Fermentation-Produced Chymosin (FPC) — Hidden Processing Agent — Is It Vegan?

Vegan status: Vegan

Also known as: Microbial chymosin, Recombinant chymosin, Fermentation rennet, Chymax

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.

Appears on label: No. Listed as 'enzymes' or 'rennet' on cheese labels. Indistinguishable from animal rennet in labelling unless explicitly stated as 'vegetarian rennet' or 'microbial rennet'.

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.

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.