Flavor ingredient regulatory record
(+/-)-Ethyl 3-mercapto-2-methylbutanoate
(+/-)-Ethyl 3-mercapto-2-methylbutanoate is an ester in the fruity family, FEMA GRAS under FEMA number 4392 (CAS 888021-82-7). Its odor is sweet, fruity, tropical, grape, berry.
- FEMA
- 4392
- CAS
- 888021-82-7
- JECFA
- 1928
- Formula
- C7H14O2S
GRAS status: FEMA GRAS, publication 23. Recorded by FDA in the Substances Added to Food inventory under CAS 888021-82-7.
Structure
Identity
Also known as: Butanoic acid, 3-mercapto-2-methyl-, ethyl ester, Ethyl 3-mercapto-2-methylbutanoate, Ethyl 3-mercapto-2-methylbutyrate, ethyl 3-mercapto-2-methylbutanoate, ethyl 2-methyl-3-sulfanylbutanoate, butanoic acid, 3-mercapto-2-methyl-, ethyl ester, ethyl 3-mercapto-2-methylbutyrate, (+-)-ethyl 3-mercapto-2-methylbutanoate, (+-)-ethyl 3-mercapto-2-methylbutanoate (fifh), (+-)-ethyl 3-mercapto-2-methylbutanoate [fifh], ethyl 3-mercapto-2-methylbutanoate, (+-)-, (+-)-ethyl 3-mercapto-2-methylbutanoate [fhfi].
Can (+/-)-Ethyl 3-mercapto-2-methylbutanoate be labeled natural?
(+/-)-Ethyl 3-mercapto-2-methylbutanoate occurs in nature, so the label depends on the route: (+/-)-Ethyl 3-mercapto-2-methylbutanoate won from a natural source by a physical, enzymatic or microbiological process is natural flavor in the United States, and synthesized (+/-)-Ethyl 3-mercapto-2-methylbutanoate is artificial. The EU and UK grant the natural claim only to that natural route; Mercosur and Mexico call synthetic material identical-to-natural.
- United States
- Natural or artificial, by process
- European Union and UK
- Natural only from natural material
- Mercosur and Mexico
- Natural or identical-to-natural
How each market defines the classes: natural vs artificial flavor under 21 CFR 101.22.
Regulatory status, with citations
United States
(+/-)-Ethyl 3-mercapto-2-methylbutanoate is FEMA GRAS under FEMA number 4392. It is cited in the Code of Federal Regulations at 21 CFR 172.515.
European Union and United Kingdom
No EU FL number is on file for (+/-)-Ethyl 3-mercapto-2-methylbutanoate. That is not a finding either way. The Union List covers defined flavouring substances, so natural complex materials are handled as flavouring preparations under Parts B to F and never receive a number, and substances used as additives sit under Regulation 1333/2008 instead. Confirm the position before EU or UK use.
JECFA (WHO / FAO)
JECFA number 1928.
Other US flags
Not on the California Proposition 65 list. Listed on the EPA TSCA inventory.
TSCA Inventory status
A flavor ingredient is also an industrial chemical. (+/-)-Ethyl 3-mercapto-2-methylbutanoate appears on the EPA Toxic Substances Control Act Chemical Substance Inventory under CAS 888021-82-7, where EPA names it Butanoic acid, 3-mercapto-2-methyl-, ethyl ester.
Active in US commerce
EPA designates this substance active, so no Notice of Activity Form B is required before manufacturing. What active and inactive mean.
EPA regulatory flags
| Flag | EPA definition | What it obliges |
|---|---|---|
| PMN | Indicates a commenced PMN substance. | Nothing new. The substance already went through premanufacture review and someone filed a notice of commencement, which is why it is on the Inventory. It is an existing chemical and needs no new premanufacture notice. Read more |
| S | Indicates a substance that is identified in a final Significant New Use Rule. | A significant new use notice at least 90 days before manufacture or processing for a designated new use, under 40 CFR 721.25(a). Distributing the substance can require a notice of its own, and exporting triggers TSCA section 12(b) notification. Read more |
PMN does not establish: The flag records how the substance arrived, not what may be done with it. Check the flags beside it.
S does not establish: Establishes that a section of 40 CFR part 721 subpart E names the substance. Whether your use is a designated significant new use can only be settled by reading that section.
From the EPA non-confidential TSCA Inventory, July 2026 release. EPA also maintains a confidential portion it does not publish. Search the Inventory by CAS number.
Odor and taste
Odor: Sweet, fruity, tropical, grape, berry.
Where it is used
(+/-)-Ethyl 3-mercapto-2-methylbutanoate is used in beverage, confection, fruit flavors, bakery and desserts, typically as a fruity note.
Structurally similar flavor ingredients
Flavor ingredients with a GRAS determination closest to (+/-)-Ethyl 3-mercapto-2-methylbutanoate by structure. Whether one can replace it is a sensory and regulatory call; the reformulation tool works that through.
| Material | FEMA | Similarity | Occurrence |
|---|---|---|---|
| 5-Ethyl-2-methylpyridine | 3546 | 80% | In nature |
| Butan-3-one-2-yl butanoate | 3332 | 78% | In nature |
More esters in this index
Crotonic acid · Cyclohexyl cinnamate · Hexadecyl lactate · Isobutyl acetate · alpha-Methylphenethyl butyrate · Allyl cyclohexane butyrate
(+/-)-Ethyl 3-mercapto-2-methylbutanoate FAQ
Is (+/-)-Ethyl 3-mercapto-2-methylbutanoate FEMA GRAS?
Yes. The FEMA Expert Panel lists (+/-)-Ethyl 3-mercapto-2-methylbutanoate as GRAS under FEMA number 4392. It is also codified at 21 CFR 172.515.
What are the FEMA and CAS numbers for (+/-)-Ethyl 3-mercapto-2-methylbutanoate?
(+/-)-Ethyl 3-mercapto-2-methylbutanoate is FEMA 4392, CAS 888021-82-7. FEMA files it in the fruity flavor category.
Does (+/-)-Ethyl 3-mercapto-2-methylbutanoate count as natural in the US and the EU?
Since (+/-)-Ethyl 3-mercapto-2-methylbutanoate is found in nature, US labeling follows how it was obtained: natural flavor from a natural source and a natural process, artificial when (+/-)-Ethyl 3-mercapto-2-methylbutanoate is synthesized. The EU and UK grant the natural claim only to that natural route; Mercosur and Mexico call synthetic material identical-to-natural.
Is (+/-)-Ethyl 3-mercapto-2-methylbutanoate approved in the EU?
No EU FL number is on file for (+/-)-Ethyl 3-mercapto-2-methylbutanoate. It has a JECFA evaluation (JECFA 1928), which the EU list draws on, but the Union List entry itself should be confirmed before EU use.
Has JECFA evaluated (+/-)-Ethyl 3-mercapto-2-methylbutanoate?
Yes. JECFA number 1928.
How is (+/-)-Ethyl 3-mercapto-2-methylbutanoate described, and where does it show up?
Flavorists describe (+/-)-Ethyl 3-mercapto-2-methylbutanoate as sweet, fruity, tropical, grape, berry. It is used in beverage, confection, fruit flavors, bakery and desserts.
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Sources and attribution. The identity and regulatory facts on this page are taken from the FDA Substances Added to Food inventory, a US government record, which lists this substance as (+/-)-ETHYL 3-MERCAPTO-2-METHYLBUTANOATE under CAS 888021-82-7 and carries its FEMA number, its JECFA flavor number. The inventory is searchable at FDA. FDA records its technical effect as flavoring agent or adjuvant.
A FEMA GRAS conclusion is reached by the Expert Panel of the Flavor and Extract Manufacturers Association of the United States, and the FEMA number names that conclusion. FEMA publishes its own entry for this substance in the FEMA Flavor Library, which is the authoritative record of what the Panel decided and is worth reading alongside this page.
Ambrose Compliance is not affiliated with, endorsed by, or sponsored by FEMA. FEMA and FEMA GRAS are used here as identifiers for a published regulatory determination, not as marks of any relationship between FEMA and Ambrose.
About this page. Facts come from the FDA Substances Added to Food inventory, the Code of Federal Regulations, the EPA TSCA Inventory, the EU Union List, JECFA and the Ambrose database, with FEMA's published determination cited where it applies; parts of the text are written by Ambrose AI, which can make mistakes. Check the cited source before relying on anything here. This is not regulatory or legal advice.