L-Cysteine (Dough Conditioner) — Hidden Processing Agent — Is It Vegan?

Also known as: E920, Cysteine, Reducing agent (baking)

Depends on Source

Vegan status depends on the source. Contact the manufacturer to confirm.

Not required on labels

L-Cysteine used as a direct ingredient must be listed as 'L-cysteine' or 'E920'. However, when used as a processing aid at levels that don't remain in the final product, it may not need to be declared. Most commercial bread does list it if used.

Source

An amino acid used as a dough conditioner and reducing agent in commercial bread production. Can be sourced from: (1) human or animal hair [not vegan], (2) duck or chicken feathers [not vegan], or (3) fermentation from plant sources [vegan]. Source is almost never declared.

Used In

Commercial bread, rolls, pizza bases, crackers, croissants, some pastries. It relaxes gluten and reduces mixing time in industrial bakeries. Also used in some meat flavoring compounds.

How to Avoid

Artisan bread and sourdough almost never use L-cysteine (gluten develops naturally through fermentation time). Look for breads with short, simple ingredient lists. If L-cysteine is listed, contact the manufacturer to ask about the source.

Editorial Notes

This is one of the most uncomfortable entries in the vegan database. Historically, L-cysteine was predominantly sourced from human hair collected from barbershops and salons in Asia. This is still practiced but declining. Feather-derived cysteine (from poultry processing) is now more common. Fermentation-derived cysteine is available and increasingly used by brands targeting vegan and kosher markets.