E920 - L-cysteine
By the Daat team · Updated October 30, 2026
E920, L-cysteine, softens dough in industrial baking. It is often made from feathers or hair, sometimes by fermentation.
It shortens kneading time and helps dough stretch, so it is common in industrial bread and pastries. Much of the world supply still comes from poultry feathers, but there is also a fermented version, and the label does not tell them apart.
How common is it? 0.5% of the products we checked, 92 in all, led by bread and cheese.
E920 at a glance
| Fact | Value |
|---|---|
| Name | L-cysteine |
| Function | Flour treatment agent |
| Origin | Plant or animal - not stated on the label |
| Vegan / vegetarian | Depends on the source / Depends on the source |
Is E920 vegan?
You cannot tell from the label. E920 can come from a plant or an animal source; only a vegan certification or the manufacturer can settle it.