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Doubtful — depends on source
E920 (L-Cysteine) is a dough conditioner that can be produced synthetically, by microbial fermentation, or extracted from feathers or human hair — so it is treated as doubtful (mushbooh) unless the source is known.
L-Cysteine is an amino acid used to soften and condition dough, helping to speed up bread-making and improve texture. It is notable because it can be made in very different ways — including from duck or chicken feathers, and historically from human hair, as well as synthetically or by fermentation.
Produced by microbial fermentation or synthesis, or extracted by hydrolysing keratin from feathers or hair. The source is almost never stated on the label.
L-Cysteine is doubtful because of its possible sources. Synthetic and microbial (fermentation) L-cysteine is halal. Feather-derived L-cysteine raises the question of the bird's source, and human-hair-derived L-cysteine is rejected by scholars as it should not come from human parts. Because the source is not stated, it is treated as doubtful until confirmed.
It may be found in — this does not mean every product below contains it.
L-CysteineL-Cysteine hydrochlorideE920Flour treatment agent (E920)INS number: 920
In Singapore, verify the finished product on the MUIS HalalSG register or contact the manufacturer, since the source of L-cysteine is not printed and matters for its halal status.
Check MUIS HalalSGSources: EFSA, FAO/WHO, MUIS · Last reviewed: July 2026 · This guidance is not certification.
It depends on the source. Synthetic and microbial L-cysteine is halal; feather-derived is doubtful and human-hair-derived is not acceptable. Since the source is usually unstated, treat it as doubtful and verify.
It can be — historically some L-cysteine was made from human hair, which scholars reject. It can also come from duck/chicken feathers or from synthetic/microbial production. Verify the source.
It is used mainly in bread and bakery dough (buns, bagels, pizza, wraps).
'L-Cysteine', 'L-Cysteine hydrochloride' or 'E920'.
Humble Halal methodology: we classify additives by their common origin, not by any specific product. A generally-halal ingredient does not make a finished product halal-certified. This page is general guidance, not certification or religious/legal advice — always verify the complete product. Last reviewed July 2026.