L-Cysteine

E number E920CAS 52-90-4

Listed as a preservative, a flavour enhancer and a flour treatment agent by Canada and the US.

Listed as preservatives (CA) · flavour enhancers (US) · flour treatment agents (US) · dough strengtheners (US) · nutrient supplements (US) · flavouring agents and adjuvants (US)
Chemical structure of L-Cysteine, from PubChem compound 5862
Structure from PubChem CID 5862 (National Library of Medicine, public domain). A depiction of one compound: where a listing covers a family, or a substance has no single structure, this page shows none.

L-Cysteine is an amino acid used as a dough conditioner: it relaxes gluten, shortening mixing time in industrial bread. Its source is a common dietary question, because it can be made from animal keratin as well as by fermentation.

Where it is and isn’t permitted

Status of L-Cysteine by jurisdiction. Every jurisdiction this site covers is listed, including those where the substance does not appear.
JurisdictionStatusScope and limitsCitation
Australia and New ZealandFood Standards Australia New ZealandPermitted

2 food categories

no numerical limit (good manufacturing practice)

Show every food category
  • 4.1.3.2 Root and tuber vegetables — GMP
  • 4.1.3.3 Avocados and bananas — GMP
Food Standards Code, Schedule 15, S15—5and 1 further provisionretrieved 2026-10-17
CanadaHealth CanadaPermitted

no numerical limit (good manufacturing practice)

In: Nutritional supplements that meet the requirements of section B.24.201 of the Food and Drug Regulations. Purpose: Preservative. Limit: Good Manufacturing Practice.

Health Canada, List of Permitted Preservatives (List 11), item C.9retrieved 2026-10-17
European UnionEuropean Commission / EFSAPermitted, with conditions

70 food categories

highest permitted level 1,000 mg/kg

Show every food category
  • 1.3 unflavoured fermented milk products heat-treated after fermentation — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 1.4 flavoured fermented milk products including heat-treated products — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 1.6.3 other creams — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 1.7.1 unripened cheese excluding products falling in category 16Permitted as a member of Group I, Additives. except mozzarella.
  • 1.7.5 processed cheese — several limitsPermitted as a member of Group I, Additives. except E 425 ML = 10000 mg/kg; E 620 to E 625, ML =10000 mg/kg individually or in combination, expressed as glutamic acid;E 626 to E 635, ML = 500 mg/kg individually or in combination, expressedas guanylic acid.
  • 1.7.6 cheese products (excluding products falling in category 16) — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 1.8 Dairy analogues, including beverage whiteners — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 10.2 processed eggs and egg products — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML =10000 mg/kg individually or in combination, expressed as glutamic acid;E 626 to E 635, ML = 500 mg/kg individually or in combination, expressedas guanylic acid.
  • 11.2 Other sugars and syrups — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 12.1.2 salt substitutes — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 12.2.2 Seasonings and condiments — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 12.3 Vinegars and diluted acetic acid (diluted with water to 4-30 % by volume) — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 12.4 Mustard — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 12.5 Soups and broths — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 12.6 Sauces — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 12.7 Salads and savoury-based sandwich spreads — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 12.8 Yeast and yeast products — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 12.9 Protein products excluding products covered in category 1 8 — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 13.1.3 Processed cereal-based foods and baby foods as defined by Regulation (EU) No 609/2013 — 1,000 mg/kgML = 1000 mg/kg. only biscuits for infants and young children.
  • 13.2 Foods for special medical purposes as defined by Regulation (EU) No 609/2013 (excluding products from food category 13.1.5.) — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 13.3 Total diet replacement for weight control food as defined by Regulation (EU) No 609/2013 — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 14.1.2 Fruit juices as defined by Directive 2001/112/EC and vegetable juicesPermitted as a member of Group I, Additives. only vegetable juices.
  • 14.1.3 Fruit nectars as defined by Directive 2001/112/EC and vegetable nectars and similar productsPermitted as a member of Group I, Additives. only vegetable nectars, E 420, E421, E 953, E965, E 966, E 967 and E 968 may not be used.
  • 14.1.4 Flavoured_drinksPermitted as a member of Group I, Additives. E 420, E 421, E 953, E 965, E 966 and E 967 may not be used E 968 may not be used except where specifically provided for in this food category.
  • 14.1.5.2 otherPermitted as a member of Group I, Additives. excluding unflavoured leaf tea; including flavoured instant coffee; E 420, E421, E 953, E965, E 966, E 967 and E 968 may not be used in drinks.
  • 14.2.3 Cider and perryPermitted as a member of Group I, Additives. E 420, E421, E 953, E965, E 966, E 967 and E 968 may not be used.
  • 14.2.4 Fruit wine and made winePermitted as a member of Group I, Additives. E 420, E421, E 953, E965, E 966, E 967 and E 968 may not be used.
  • 14.2.5 MeadPermitted as a member of Group I, Additives. E 420, E421, E 953, E965, E 966, E 967 and E 968 may not be used.
  • 14.2.6 Spirit drinks as defined in Regulation (EU) 2019/787Permitted as a member of Group I, Additives. except whisky or whiskey; E 420, E421, E 953, E 965, E 966, E 967 and E 968 may not be used except in liqueurs.
  • 14.2.7.1 Aromatised winesPermitted as a member of Group I, Additives. E 420, E421, E 953, E965, E 966, E 967 and E 968 may not be used.
  • 14.2.7.2 Aromatised wine-based drinksPermitted as a member of Group I, Additives. E 420, E421, E 953, E965, E 966, E 967 and E 968 may not be used.
  • 14.2.7.3 Aromatised wine-product cocktailsPermitted as a member of Group I, Additives. E 420, E421, E 953, E965, E 966, E 967 and E 968 may not be used.
  • 14.2.8 Other alcoholic beverages including mixtures of alcoholic beverages with non-alcoholic beverages and other alcoholic beverages based on distilled alcohol with alcoholic strength by volume less than 15 %Permitted as a member of Group I, Additives. E 420, E421, E 953, E 965, E 966, E 967 and E 968 may not be used.
  • 15.1 Potato- cereal- flour- or starch-based snacks — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 15.2 Processed nuts — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 16 Desserts excluding products covered in category 1 3 and 4 — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 17.1 food supplements supplied in a solid form excluding food supplements for infants and young children’,Permitted as a member of Group I, Additives. E 410, E 412, E 415, E 417 and E 425 may not be used to produce dehydrated food supplements intended to rehydrate on ingestion.
  • 17.2 food supplements supplied in a liquid form excluding food supplements for Infants and young children — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 18 Processed foods not covered by categories 1 to 17 — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 18.1 Processed foods not covered by categories 18.2 and 18.3, excluding foods for infants and young children — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 18.2 Meal replacement for weight control as referred to in Commission Regulation (EU) No 432/2012 — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 18.3 Food specially produced to reduce the gluten content of gluten-containing ingredients or substitute the gluten-containing ingredientsPermitted as a member of Group I, Additives. Including dry pasta.
  • 2.2.2 Other fat and oil emulsions including spreads as defined by Regulation (EC) No 1234/2007 and liquid emulsions — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 2.3 Vegetable oil pan spray — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 3 edible ices — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 4.2.1 dried fruit and vegetablesPermitted as a member of Group I, Additives. E 410, E 412, E 415 and E 417 may not be used to produce dehydrated foods intended to rehydrate on ingestion.
  • 4.2.2 fruit and vegetables in vinegar oil or brine — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 4.2.4.1 fruit and vegetable preparations excluding compote — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 4.2.5.4 nut butters and nut spreads — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 4.2.6 processed potato products — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 5.1 Cocoa and chocolate products as covered by Directive 2000/36/ECPermitted as a member of Group I, Additives. only energy-reduced or with no added sugars.
  • 5.2 Other confectionery including breath freshening micro-sweetsPermitted as a member of Group I, Additives. The substances listed under numbers E 400, E 401, E 402, E 403, E 404, E 406, E 407, 407a, E 410, E 412, E 413, E 414, E 415, E 417, E 418, E 425 and E 440 may not be used in jelly mini-cups, defined, for the purpose of this Regulation, as jelly confectionery of a firm consistence, contained in semi rigid mini-cups or mini-capsules, intended to be ingested in a single bite by exerting pressure on the mini-cups or mini-capsule to project the confectionery into the mouth; E 410, E 412, E 415 E 417 may not be used to produce dehydrated foods intended to rehydrate on ingestion. E425 may not be used in jelly confectionery.
  • 5.3 chewing gum — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 5.4 Decorations, coatings and fillings, except fruit-based fillings covered by category 4.2.4 — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 6.2.1 flours — quantum satisquantum satis.
  • 6.2.2 starches — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 6.3 breakfast cereals — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 6.4.2 Dry pasta — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 6.4.4 Potato GnocchiPermitted as a member of Group I, Additives. except fresh refrigerated potato gnocchi.
  • 6.4.5 fillings of stuffed pasta (ravioli and similar) — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 6.5 Noodles — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 6.6 Batters — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 6.7 pre-cooked or processed cereals — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 7.1 Bread and rollsPermitted as a member of Group I, Additives. except products in 7.1.1 and 7.1.2.
  • 7.2 Fine bakery wares — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 8.3.1 Non-heat-treated processed meat — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 8.3.2 Heat-treated meat productsPermitted as a member of Group I, Additives. except foie gras, foie gras entier, blocs de foie gras, Libamáj, libamáj egészben, libamáj tömbben.
  • 8.3.3 Casings and coatings and decorations for meat — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 9.2 Processed fish and fishery products including molluscs and crustaceans — several limitsPermitted as a member of Group I, Additives. ML = quantum satis; except E 425 ML = 10000 mg/kg; E 620 to E 625, ML = 10000 mg/kg individually or in combination, expressed as glutamic acid; E 626 to E 635, ML = 500 mg/kg individually or in combination, expressed as guanylic acid.
  • 9.3 fish roePermitted as a member of Group I, Additives. only processed fish roe.
Regulation (EC) No 1333/2008, Annex IIand 69 further provisionsretrieved 2026-10-18
Great BritainFood Standards Agency / Food Standards ScotlandPermitted, with conditions

68 food categories

highest permitted level 1,000 mg/kg or mg/l

Show every food category
  • 1.3 Unflavoured fermented milk products, heat-treated after fermentation — quantum satisPermitted as a member of Group I. quantum satis.
  • 1.4 Flavoured fermented milk products including heat-treated products — quantum satisPermitted as a member of Group I. quantum satis.
  • 1.6.3 Other creams — quantum satisPermitted as a member of Group I. quantum satis.
  • 1.7.1 Unripened cheese excluding products falling in category 16 — quantum satisPermitted as a member of Group I. quantum satis. except mozzarella.
  • 1.7.5 Processed cheese — quantum satisPermitted as a member of Group I. quantum satis.
  • 1.7.6 Cheese products (excluding products falling in category 16) — quantum satisPermitted as a member of Group I. quantum satis.
  • 1.8 Dairy analogues, including beverage whiteners — quantum satisPermitted as a member of Group I. quantum satis.
  • 10.2 Processed eggs and egg products — quantum satisPermitted as a member of Group I. quantum satis.
  • 11.2 Other sugars and syrups — quantum satisPermitted as a member of Group I. quantum satis.
  • 12.1.2 Salt substitutes — quantum satisPermitted as a member of Group I. quantum satis.
  • 12.2.2 Seasonings and condiments — quantum satisPermitted as a member of Group I. quantum satis.
  • 12.3 Vinegars and diluted acetic acid (diluted with water to 4-30 % by volume) — quantum satisPermitted as a member of Group I. quantum satis.
  • 12.4 Mustard — quantum satisPermitted as a member of Group I. quantum satis.
  • 12.5 Soups and broths — quantum satisPermitted as a member of Group I. quantum satis.
  • 12.6 Sauces — quantum satisPermitted as a member of Group I. quantum satis.
  • 12.7 Salads and savoury based sandwich spreads — quantum satisPermitted as a member of Group I. quantum satis.
  • 12.8 Yeast and yeast products — quantum satisPermitted as a member of Group I. quantum satis.
  • 12.9 Protein products, excluding products covered in category 1.8 — quantum satisPermitted as a member of Group I. quantum satis.
  • 13.1.3 Processed cereal-based foods and baby foods for infants and young children as defined by Commission Directive 2006/125/EC — 1,000 mg/kg or mg/lML = 1000. only biscuits for infants and young children.
  • 13.2 Dietary foods for special medical purposes defined in Directive 1999/21/EC (excluding products from food category 13.1.5) — quantum satisPermitted as a member of Group I. quantum satis.
  • 13.3 Dietary foods for weight control diets intended to replace total daily food intake or an individual meal (the whole or part of the total daily diet) — quantum satisPermitted as a member of Group I. quantum satis.
  • 13.4 Foods suitable for people intolerant to gluten as defined by Commission Regulation (EC) No 41/2009 — quantum satisPermitted as a member of Group I. quantum satis. including dry pasta.
  • 14.1.2 Fruit juices as defined by Directive 2001/112/EC and vegetable juices — quantum satisPermitted as a member of Group I. quantum satis. only vegetable juices.
  • 14.1.3 Fruit nectars as defined by Directive 2001/112/EC and vegetable nectars and similar products — quantum satisPermitted as a member of Group I. quantum satis. only vegetable nectars, E 420, E421, E 953, E965, E 966, E 967 and E 968 may not be used.
  • 14.1.4 Flavoured drinks — quantum satisPermitted as a member of Group I. quantum satis. E 420, E 421, E 953, E 965, E 966 and E 967 may not be used E 968 may not be used except where specifically provided for in this food category.
  • 14.1.5.2 Other — quantum satisPermitted as a member of Group I. quantum satis. excluding unflavoured leaf tea; including flavoured instant coffee; E 420, E421, E 953, E965, E 966, E 967 and E 968 may not be used in drinks.
  • 14.2.3 Cider and perry — quantum satisPermitted as a member of Group I. quantum satis. E 420, E421, E 953, E965, E 966, E 967 and E 968 may not be used.
  • 14.2.4 Fruit wine and made wine — quantum satisPermitted as a member of Group I. quantum satis. E 420, E421, E 953, E965, E 966, E 967 and E 968 may not be used.
  • 14.2.5 Mead — quantum satisPermitted as a member of Group I. quantum satis. E 420, E421, E 953, E965, E 966, E 967 and E 968 may not be used.
  • 14.2.6 Spirit drinks as defined in Regulation (EC) No 110/2008 — quantum satisPermitted as a member of Group I. quantum satis. except whisky or whiskey; E 420, E421, E 953, E965, E 966, E 967 and E 968 may not be used except in liqueurs.
  • 14.2.7.1 Aromatised wines — quantum satisPermitted as a member of Group I. quantum satis. E 420, E421, E 953, E965, E 966, E 967 and E 968 may not be used.
  • 14.2.7.2 Aromatised wine-based drinks — quantum satisPermitted as a member of Group I. quantum satis. E 420, E421, E 953, E965, E 966, E 967 and E 968 may not be used.
  • 14.2.7.3 Aromatised wine-product cocktails — quantum satisPermitted as a member of Group I. quantum satis. E 420, E421, E 953, E965, E 966, E 967 and E 968 may not be used.
  • 14.2.8 Other alcoholic drinks including mixtures of alcoholic drinks with non-alcoholic drinks and spirits with less than 15 % of alcohol — quantum satisPermitted as a member of Group I. quantum satis. E 420, E421, E 953, E965, E 966, E 967 and E 968 may not be used.
  • 15.1 Potato-, cereal-, flour- or starch-based snacks — quantum satisPermitted as a member of Group I. quantum satis.
  • 15.2 Processed nuts — quantum satisPermitted as a member of Group I. quantum satis.
  • 16 Desserts excluding products covered in categories 1, 3 and 4 — quantum satisPermitted as a member of Group I. quantum satis.
  • 17.1 Food supplements supplied in a solid form, excluding food supplements for infants and young children — quantum satisPermitted as a member of Group I. quantum satis. E 410, E 412, E 415, E 417 and E 425 may not be used to produce dehydrated food supplements intended to rehydrate on ingestion.
  • 17.2 Food supplements supplied in a liquid form, excluding food supplements for infants and young children — quantum satisPermitted as a member of Group I. quantum satis.
  • 18 Processed foods not covered by categories 1 to 17, excluding foods for infants and young children — quantum satisPermitted as a member of Group I. quantum satis.
  • 2.2.2 Other fat and oil emulsions including spreads as defined by Regulation (EC) No 1234/2007 and liquid emulsions — quantum satisPermitted as a member of Group I. quantum satis.
  • 2.3 Vegetable oil pan spray — quantum satisPermitted as a member of Group I. quantum satis.
  • 3 Edible ices — quantum satisPermitted as a member of Group I. quantum satis.
  • 4.2.1 Dried fruit and vegetables — quantum satisPermitted as a member of Group I. quantum satis. E 410, E 412, E 415 E 417 may not be used to produce dehydrated foods intended to rehydrate on ingestion.
  • 4.2.2 Fruit and vegetables in vinegar, oil, or brine — quantum satisPermitted as a member of Group I. quantum satis.
  • 4.2.4.1 Fruit and vegetable preparations excluding compote — quantum satisPermitted as a member of Group I. quantum satis.
  • 4.2.5.4 Nut butters and nut spreads — quantum satisPermitted as a member of Group I. quantum satis.
  • 4.2.6 Processed potato products — quantum satisPermitted as a member of Group I. quantum satis.
  • 5.1 Cocoa and chocolate products as covered by Directive 2000/36/EC — quantum satisPermitted as a member of Group I. quantum satis. only energy-reduced or with no added sugar.
  • 5.2 Other confectionery including breath refreshening microsweets — quantum satisPermitted as a member of Group I. quantum satis. The substances listed under numbers E 400, E 401, E 402, E 403, E 404, E 406, E 407, 407a, E 410, E 412, E 413, E 414, E 415, E 417, E 418, E 425 and E 440 may not be used in jelly mini-cups, defined, for the purpose of this Regulation, as jelly confectionery of a firm consistence, contained in semi rigid mini-cups or mini-capsules, intended to be ingested in a single bite by exerting pressure on the mini-cups or mini-capsule to project the confectionery into the mouth; E 410, E 412, E 415 E 417 may not be used to produce dehydrated foods intended to rehydrate on ingestion. E425 may not be used in jelly confectionery.
  • 5.3 Chewing gum — quantum satisPermitted as a member of Group I. quantum satis.
  • 5.4 Decorations, coatings and fillings, except fruit based fillings covered by category 4.2.4 — quantum satisPermitted as a member of Group I. quantum satis.
  • 6.2.1 Flours — quantum satisquantum satis.
  • 6.2.2 Starches — quantum satisPermitted as a member of Group I. quantum satis.
  • 6.3 Breakfast cereals — quantum satisPermitted as a member of Group I. quantum satis.
  • 6.4.2 Dry pasta — quantum satisPermitted as a member of Group I. quantum satis. only gluten free and/or pasta intended for hypoproteic diets in accordance with Directive 2009/39/EC.
  • 6.4.4 Potato gnocchi — quantum satisPermitted as a member of Group I. quantum satis. except fresh refrigerated potato gnocchi.
  • 6.4.5 Fillings of stuffed pasta (ravioli and similar) — quantum satisPermitted as a member of Group I. quantum satis.
  • 6.5 Noodles — quantum satisPermitted as a member of Group I. quantum satis.
  • 6.6 Batters — quantum satisPermitted as a member of Group I. quantum satis.
  • 6.7 Pre-cooked or processed cereals — quantum satisPermitted as a member of Group I. quantum satis.
  • 7.1 Bread and rolls — quantum satisPermitted as a member of Group I. quantum satis. except products in 7.1.1 and 7.1.2.
  • 7.2 Fine bakery wares — quantum satisPermitted as a member of Group I. quantum satis.
  • 8.3.1 Non-heat-treated meat products — quantum satisPermitted as a member of Group I. quantum satis.
  • 8.3.2 Heat-treated meat products — quantum satisPermitted as a member of Group I. quantum satis. except foie gras, foie gras entier, blocs de foie gras, Libamáj, libamáj egészben, libamáj tömbben.
  • 8.3.3 Casings and coatings and decorations for meat — quantum satisPermitted as a member of Group I. quantum satis.
  • 9.2 Processed fish and fishery products including mollusks and crustaceans — quantum satisPermitted as a member of Group I. quantum satis.
  • 9.3 Fish roe — quantum satisPermitted as a member of Group I. quantum satis. only processed fish roe.
Assimilated Regulation (EC) No 1333/2008and 67 further provisionsretrieved 2026-10-18
JapanConsumer Affairs AgencyNo listing matchedThis site imports only Japan’s list of designated additives (Appended Table 1 to the Regulations for Enforcement of the Food Sanitation Act), matched by English name. Existing additives, natural flavouring agents and ordinary foods used as additives are permitted outside that list and are not imported, so an empty row does not show that Japan does not permit the substance.
South KoreaMinistry of Food and Drug SafetyNo listing matchedThis site imports Part III of South Korea’s Standards and Specifications for Food Additives, matched by CAS number, then INS number, then exact name. Mixed preparations and sanitisers are not imported, and an entry whose identifiers disagreed with a page’s is held for review, so an empty row does not show that South Korea does not permit the substance.
United StatesFood and Drug AdministrationPermitted21 CFR 184.1271retrieved 2026-10-17
Codex AlimentariusCodex Alimentarius Commission / JECFANot listedDoes not appear on this jurisdiction’s permitted list. That is not the same as being prohibited.

How much is permitted

A listing usually limits the quantity as well as the food. Only one of the forms that takes is a figure: quantum satis and good manufacturing practice permit the amount the technological effect requires and no more, which is a limit rather than the absence of one. Figures below are the range across every food category this page is listed in, and categories differ between regulators — see how much is permitted.

Australia and New Zealand—2 GMP
Canada—1 GMP
European Union1,000 mg/kg1 numeric limit, 46 several limits, 1 quantum satis, 22 no quantity stated
Great Britain1,000 mg/kg1 numeric limit, 67 quantum satis
United States—1 no quantity stated

What it is made from

Now produced chiefly by bacterial fermentation, and also by extraction from keratin — duck and chicken feathers, hog bristle, and historically human hair. Manufacturers need not declare which route was used.

  • Vegan status depends on the source
  • Vegetarian status depends on the source
  • May raise a halal question
  • May raise a kosher question

This is not an omission. What this additive is made from is not fixed — depending on the manufacturer it may be plant, animal or microbial in origin, nobody is required to say which, and the same product can change source between production runs. Ask the manufacturer if it matters to you; a label cannot answer it.

Compare other additives on the dietary indexes.

CAS registry number
52-90-4
InChIKey
XUJNEKJLAYXESH-REOHCLBHSA-N
PubChem
CID 5862

How the EU defines it

The legal specification an additive must meet to be sold as this E number in the EU — what it is, how it may be made, and the purity it must reach. From Commission Regulation (EU) No 231/2012.

E 920 L-cysteine

L-cysteine hydrochloride or hydrochloride monohydrate. Human hair may not be used as a source for this substance

Assay, identification and purity criteria

Description and assay

Einecs
200-157-7 (anhydrous)
Chemical formula
C₃H₇NO₂S · HCl · nH₂O (where n = 0 or 1)
Molecular weight
157,62 (anhydrous)
Assay
Content not less than 98,0 % and not more than 101,5 % on the anhydrous basis
Description
White powder or colourless crystals

Identification

Solubility
Freely soluble in water and in ethanol
Melting range
Anhydrous form melts at about 175 °C
Specific rotation
[α]D ²⁰: between + 5,0° and + 8,0° or [α]D ²⁵: between + 4,9° and 7,9°

Purity criteria

Loss on drying
Between 8,0 % and 12,0 % Not more than 2,0 % (anhydrous form)
Residue on ignition
Not more than 0,1 %
Ammonium-ion
Not more than 200 mg/kg
Arsenic
Not more than 1,5 mg/kg
Lead
Not more than 5 mg/kg

Commission Regulation (EU) No 231/2012, Annex, E 920

Authorised in other additives, enzymes, flavourings and nutrients

These authorisations are not for use in food. They let this substance be used inside another additive, a food enzyme, a flavouring or a nutrient preparation — often as a carrier — and it reaches food only as part of that product. Annex III to Regulation (EC) No 1333/2008.

PartMay be used inMaximum levelCitation
Annex III, Part 3: Food additives including carriers in food enzymesFood enzymesNote (1): Including enzymes authorised as food additives.In enzyme preparation: 10 000 mg/kg In final food except beverages: 10 mg/kg In beverages: 5 mg/lRegulation (EC) No 1333/2008, Annex III, Part 3

Every name it appears under

84 recorded names. A label may use any of them.

E number

  • E920
  • E921

CAS registry number

  • 202114-66-7
  • 52-90-4

As it appears in regulation

  • L-Cysteine

Other names

  • (2R)-2-amino-3-mercapto-propionic acid;hydrochloride
  • (2R)-2-amino-3-mercaptopropanoate
  • (2R)-2-amino-3-mercaptopropanoic acid
  • (2R)-2-amino-3-sulfanyl-propanoic acid
  • (2R)-2-amino-3-sulfanylpropanoate
  • (2R)-2-amino-3-sulfanylpropanoic acid
  • (2R)-2-azaniumyl-3-sulfanylpropanoate
  • (R)-(+)-Cysteine
  • (R)-2-Amino-3-mercaptopropanoic acid
  • (R)-2-Amino-3-mercaptopropionic acid
  • (R)-2-Amino-3-sulfanyl-propanoic acid
  • (R)-Cysteine
  • 2-amino-3-mercaptopropanoate
  • 2-Amino-3-mercaptopropanoic acid
  • 2-Amino-3-mercaptopropanoic acid, (R)-
  • 2-Amino-3-mercaptopropionic acid
  • 2-amino-3-sulfanylpropanoic acid
  • 2-azaniumyl-3-sulfanylpropanoate
  • [R-(R*,R*)]-3,3'-dithiobis [2-aminopropanoic acid]
  • alpha-Amino-beta-mercaptopropanoic acid, L-
  • alpha-Amino-beta-mercaptopropionic acid, L-
  • alpha-Amino-beta-thiolpropionic acid
  • alpha-Amino-beta-thiolpropionic acid, L-
  • beta-Mercaptoalanine
  • beta-Mercaptoalanine, L-
  • bis(β-amino-β-carboxyethyl) disulfide
  • CCRIS 912
  • cisteina
  • Cisteinum
  • Cisteinum (Latin)
  • Cys
  • CYSTE
  • Cystein
  • cysteine
  • Cysteine, L-
  • Cysteinum
  • Dicysteine
  • E 920
  • FEMA No. 3263
  • FREE CYSTEINE
  • H-Cys-OH
  • Half cystine
  • Half-cystine
  • HSDB 2109
  • L Cysteine
  • L-(+)-Cysteine
  • L-2-Amino-3-mercaptopropanoic acid
  • L-2-Amino-3-mercaptopropionic acid
  • L-Alanine, 3-mercapto-
  • L-Cys
  • l-cystAine
  • L-Cystein
  • L-cysteine
  • L-Cysteine 7403
  • L-Cysteine from non-animal source
  • L-Cysteine High
  • L-Cysteine High 7404
  • l-cysteinum
  • L-Zystein
  • Propanoic acid, 2-amino-3-mercapto-, (R)-
  • Thioserine
  • α-diamino-beta-dithiolactic acid
  • β,β'-diamino-β,β'-dicarboxydiethyl disulfide
  • β,β'-dithiodialanine

Systematic names

  • (2R)-2-amino-3-[[(2R)-2-amino-2-carboxyethyl]disulfanyl]propanoic acid
  • (2R)-2-amino-3-sulfanylpropanoic acid

Hazard reference values

No reference value for this substance in the sources we hold.

Evidence and how bodies read it

Studies, and the differing conclusions regulators drew from them, are curated rather than machine-read, and none has been written for this substance yet.

Common questions

Assembled from what is above, in the words the questions are usually asked in. Each answer is the same statement the relevant section makes, with the same citations behind it.

What is E 920?
E 920 is L-Cysteine. L-Cysteine is an amino acid used as a dough conditioner: it relaxes gluten, shortening mixing time in industrial bread. Its source is a common dietary question, because it can be made from animal keratin as well as by fermentation.
What is L-Cysteine used for in food?
It is listed as a preservative, a flavour enhancer and a flour treatment agent — the role Canada and the US assign it. This page shows every function each regulator records, with the citation for each.
Where is L-Cysteine permitted?
Of the seven regulators this site reads, Australia and New Zealand, Canada, the EU, Great Britain and the US permit it. Each permission is for named foods at named levels, not a blanket one; the table on this page gives them with citations.
Is L-Cysteine vegan?
It depends on the source, and a label will not tell you. L-Cysteine can be made from plant or animal material, manufacturers are not obliged to say which, and the same product can change between production runs. Anyone who needs to know has to ask the manufacturer.

Sources for this page

  • anz retrieved 2026-10-17
  • ca retrieved 2026-10-17
  • eu retrieved 2026-10-18
  • gb retrieved 2026-10-18
  • ecfr retrieved 2026-10-17
  • euspecs retrieved 2026-10-18

Full licence terms and publisher details on Sources. How this page is built and updated: Method.

Machine-readable: a JSON record of this additive is given on request —how to ask for access.

Follow changes to L-Cysteine:Atom feed — regulatory events, and any change the weekly refresh detects in its provisions.