Flavor ingredient regulatory record
Trithioacetone
Trithioacetone is a thiol in the sulfur family, FEMA GRAS under FEMA number 3475 (CAS 828-26-2). Its odor is pungent, onion, garlic, sulfurous.
- FEMA
- 3475
- CAS
- 828-26-2
- JECFA
- 543
- EU FL
- 15.009
- Formula
- C9H18S3
- EC
- 212-582-5
GRAS status: FEMA GRAS, publication 9. Recorded by FDA in the Substances Added to Food inventory under CAS 828-26-2.
Structure
Identity
Also known as: 1,3,5-Trithiane, 2,2,4,4,6,6-hexamethyl-, s-Trithiane, 2,2,4,4,6,6-hexamethyl-, s-Trithiane, hexamethyl-, 2,2,4,4,6,6-Hexamethyl-1,3,5-trithiane, Hexamethyl-s-trithiane, 2,2,4,4,6,6-Hexamethyl-s-trithiane, Hexamethyl-1,3,5-trithiane, 2,2,4,4,6,6-hexamethyl-1,3,5-trithiane, 2,2,4,4,6,6-hexamethyl-s-trithiane, hexamethyl-1,3,5-trithiane, hexamethyl-s-trithiane, 1,3,5-trithiane, 2,2,4,4,6,6-hexamethyl-.
Can Trithioacetone be labeled natural?
The process decides for trithioacetone. It occurs in nature, so a natural-source, natural-process material is natural flavor in the US and synthetic trithioacetone is artificial. In the EU and UK the natural claim likewise needs the natural route, while Mercosur and Mexico keep a third class, identical-to-natural, for the synthetic material.
- 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
Trithioacetone is FEMA GRAS under FEMA number 3475. It is cited in the Code of Federal Regulations at 21 CFR 172.515.
European Union and United Kingdom
Listed on the Union List of flavouring substances as FL 15.009, Annex I Part A under Regulation (EC) 1334/2008, evaluation status approved (JECFA). The UK retains the same list.
JECFA (WHO / FAO)
JECFA number 543, evaluated at the 53rd meeting in 1999. No safety concern at current levels of intake when used as a flavouring agent.
Other US flags
Not on the California Proposition 65 list.
TSCA Inventory status
A flavor ingredient is also an industrial chemical. Trithioacetone appears on the EPA Toxic Substances Control Act Chemical Substance Inventory under CAS 828-26-2, where EPA names it 1,3,5-Trithiane, 2,2,4,4,6,6-hexamethyl-.
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 publishes no regulatory flags on this listing. What the flags mean.
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: Pungent, onion, garlic, sulfurous.
Where it is used
Trithioacetone is used in savory dishes, seasonings, sauces and condiments, typically as a sulfur note.
Structurally similar flavor ingredients
Flavor ingredients with a GRAS determination closest to Trithioacetone by structure. Whether one can replace it is a sensory and regulatory call; the reformulation tool works that through.
| Material | FEMA | Similarity | Occurrence |
|---|---|---|---|
| 3,3,5-Trimethyl cyclohexanol | 3962 | 63% | In nature |
| Eucalyptol | 2465 | 57% | In nature |
| 4-(Methylthio)-4-methyl-2-pentanone | 3376 | 57% | In nature |
| Isophorone | 3553 | 56% | In nature |
| p-Mentha-8-thiol-3-one | 3177 | 53% | In nature |
More thiols in this index
2-Mercaptoanisole · 2-Mercapto-3-butanol · 2-Naphthalenethiol · 4-Mercapto-4-methyl-2-hexanone · 2,6-(Dimethyl)thiophenol · (+/-)-2-Mercaptomethylpentan-1-ol
Trithioacetone FAQ
Does trithioacetone have FEMA GRAS status?
Trithioacetone holds FEMA GRAS status under FEMA number 3475. The Code of Federal Regulations lists it at 21 CFR 172.515.
How do I cite trithioacetone by FEMA or CAS number?
Cite trithioacetone as FEMA 3475 or CAS 828-26-2; both point to the same entry. Its flavor category is sulfur.
What does trithioacetone smell and taste like, and where is it used?
The odor of trithioacetone is pungent, onion, garlic, sulfurous. Typical uses are savory dishes, seasonings, sauces and condiments.
What did JECFA conclude about trithioacetone?
JECFA evaluated trithioacetone at the 53rd meeting in 1999 under JECFA number 543. The panel concluded: No safety concern at current levels of intake when used as a flavouring agent.
Can trithioacetone be used in the EU and UK?
Yes. FL 15.009 is the Union List entry for trithioacetone, annex I Part A, under Regulation 1334/2008, and the UK keeps the same list.
Can trithioacetone be labeled a natural flavor?
Nature makes trithioacetone, which is why the US label turns on process. A natural route gives natural flavor; synthesis gives artificial trithioacetone, same molecule. The EU and UK follow the same logic without a middle class; Mercosur and Mexico label synthetic trithioacetone identical-to-natural.
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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 TRITHIOACETONE under CAS 828-26-2 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.