Chymosin A from Escherichia coli K-12
Aspartyl protease · Chymosin · Chymosin A · Chymosin A from Escherichia coli K-12 · Chymosin A from Escherichia coli K-12 containing the Prochymosin A Gene · Milk-clotting enzyme · RenninCAS 84484-18-4
Listed as a thickener, a stabiliser and an enzyme by the US.
Listed as thickeners (US) · stabilisers (US) · enzymes (US) · processing aids (US)
- United States: Stabilizers and thickeners — 21 CFR 184.1685, citing 21 CFR 170.3(o)(28)
- United States: Stabilizers and thickeners — 21 CFR 184.1685, citing 21 CFR 170.3(o)(28)
- United States: Enzymes — 21 CFR 184.1685, citing 21 CFR 170.3(o)(9)
- United States: Processing aids — 21 CFR 184.1685, citing 21 CFR 170.3(o)(24)
Chymosin is the enzyme in calf rennet that clots milk, and this is the A form of it produced by fermentation instead of from calves. JECFA notes that preparations may contain caramel colour so that they can be told apart.
Where it is and isn’t permitted
| Jurisdiction | Status | Scope and limits | Citation |
|---|---|---|---|
| Australia and New Zealand | No listed food uses foundThis site has not matched this substance to any food use on this jurisdiction’s list of authorised food additives. A food additive may be used only in foods that list names. Flavourings, enzymes, processing aids and added nutrients are regulated separately and do not appear on it. | ||
| Canada | No listing matchedHealth Canada’s lists name additives without E or INS numbers, so this site matches them by exact name. A substance listed there under a name this site does not recognise has no row here. | ||
| European Union | No listed food uses foundThis site has not matched this substance to any food use on this jurisdiction’s list of authorised food additives. A food additive may be used only in foods that list names. Flavourings, enzymes, processing aids and added nutrients are regulated separately and do not appear on it. | ||
| Great Britain | No listed food uses foundThis site has not matched this substance to any food use on this jurisdiction’s list of authorised food additives. A food additive may be used only in foods that list names. Flavourings, enzymes, processing aids and added nutrients are regulated separately and do not appear on it. | ||
| Japan | No 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 Korea | No 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 States | Permitted | Named in 21 CFR 184.1685, a direct food substance the regulation affirms as generally recognized as safe: chymosin preparation derived, via fermentation, from a nonpathogenic and n …Named in 21 CFR 184.1685, a direct food substance the regulation affirms as generally recognized as safe: chymosin preparation derived, via fermentation, from a nonpathogenic and nontoxigenic strain of Escherichia coli K-12 containing the prochymosin gene (paragraph (a)(2)). The section is held on this site as the page rennet-animal-derived-and-chymosin-preparation-fermentation-derived; read it for the conditions. | 21 CFR 184.1685retrieved 2026-10-18 |
| Codex Alimentarius | Not 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.
| United States | — | 1 no quantity stated |
|---|
No regulator sets a figure for Chymosin A from Escherichia coli K-12. That is not an absence of control: where the listing says quantum satis or good manufacturing practice, the quantity is limited to what the effect requires.
What it is made from
Made by fermenting Escherichia coli K-12 carrying the calf prochymosin gene, then converting the prochymosin to chymosin and purifying it. No animal material is used in the production.
- CAS registry number
- 84484-18-4
How JECFA defines it
The international specification for identity and purity, prepared by the Joint FAO/WHO Expert Committee on Food Additives and published by FAO. It is a different document from any above, written by a different body and revised on its own cycle; it is advisory, and a country adopts it or does not.
Chymosin A from Escherichia coli K-12 containing the Prochymosin A Gene
Synonyms: Rennin, milk-clotting enzyme, chymosin, chymosin A, aspartyl protease Aspartyl protease; Chymosin; Chymosin A; Milk-clotting enzyme; Rennin
Assay, identification and purity criteria
Description and assay
- Specification history
- CHYMOSIN A from ESCHERICHIA COLI K-12 containing the PROCHYMOSIN A GENE Prepared at the 53rd JECFA (1999) and published in FNP 52 Add 7 (1999), superseding tentative specifications prepared at the 37th JECFA (1990), published in FNP 52 (1992). ADI "Not specified" established at the 37th JECFA in 1990.
- C.A.S. number
- 84484-18-4
- SOURCES
- Produced intracellularly by the controlled fermentation of Escherichia coli K-12 containing the bovine prochymosin A gene. The strain is non-pathogenic and non-toxicogenic (for example, JA198). Prochymosin is liberated by cell disruption followed by harvesting of the prochymosin by centrifugation or membrane concentration and washing with buffer solution. The residual production cells are inactivated by acid treatment, then the prochymosin is dissolved in buffer solution and after pH adjustment the solution is filtered. Prochymosin is activated to chymosin by acid treatment, followed by final purification via anion-exchange chromatography and elution with a buffered salt solution.
- Active principles
- Chymosin
- Systematic names and numbers
- None (EC 3.4.23.4)
- Reactions catalyzed
- Cleaves a single bond in kappa-casein
- DESCRIPTION
- Clear, colourless or slightly coloured aqueous solution containing the active enzyme; preparations may contain caramel colour to facilitate their identification in cheese manufacture.
- FUNCTIONAL USES
- Enzyme preparation Used in clotting of milk for cheese production
- GENERAL SPECIFICATIONS
- Must conform to the General Specifications for Enzyme Preparations used in Food Processing (see Volume Introduction)
Identification
- Milk clotting activity (Vol. 4)
- The sample shows milk clotting activity
Every name it appears under
7 recorded names. A label may use any of them.
Other names
- Aspartyl protease
- Chymosin
- Chymosin A
- Chymosin A from Escherichia coli K-12
- Chymosin A from Escherichia coli K-12 containing the Prochymosin A Gene
- Milk-clotting enzyme
- Rennin
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 Chymosin A from Escherichia coli K-12?
- Chymosin is the enzyme in calf rennet that clots milk, and this is the A form of it produced by fermentation instead of from calves. JECFA notes that preparations may contain caramel colour so that they can be told apart.
- What is Chymosin A from Escherichia coli K-12 used for in food?
- It is listed as a thickener, a stabiliser and an enzyme — the role the US assigns it. This page shows every function each regulator records, with the citation for each.
- Is Chymosin A from Escherichia coli K-12 banned in Europe?
- No. Chymosin A from Escherichia coli K-12 does not appear on the EU's list of authorised food additives, which is not the same as being banned: the EU permits an additive only where it has authorised it, and usually the reason for an absence is that no one applied. The EU has made no finding against this substance. It does mean it may not be used as a food additive in the EU today.
- Where is Chymosin A from Escherichia coli K-12 permitted?
- Of the seven regulators this site reads, the US permits it. Each permission is for named foods at named levels, not a blanket one; the table on this page gives them with citations.
Sources for this page
- us-listings retrieved 2026-10-18
- jecfaspecs retrieved 2026-09-23
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