Flavor ingredient regulatory record
4,5-Dimethyl-2-isobutylthiazole
4,5-Dimethyl-2-isobutylthiazole is a thiazole in the savory family, FEMA GRAS under FEMA number 4647 (CAS 53498-32-1). Its odor is earthy, nutty, roasted, savory, meaty.
- FEMA
- 4647
- CAS
- 53498-32-1
- JECFA
- 2109
- EU FL
- 15.078
- Formula
- C9H15NS
- EC
- 258-586-0
GRAS status: FEMA GRAS, publication 24. Recorded by FDA in the Substances Added to Food inventory under CAS 53498-32-1.
Structure
Identity
Also known as: Thiazole, 4,5-dimethyl-2-(2-methylpropyl)-, 4,5-Dimethyl-2-(2-methylpropyl)thiazole, 2-Isobutyl-4,5-dimethylthiazole, 2-isobutyl-4,5-dimethylthiazole, geranium thiazole, thiazole, 4,5-dimethyl-2-(2-methylpropyl)-, 2-isobutyl-4,5-dimethyl thiazole, 4,5-dimethyl-2-(2-methylpropyl)-1,3-thiazole, 4,5-dimethyl-2-isobutyl thiazole, 2-isobutyl-4,5-dimethyl-thiazole, 2-iso-butyl-4,5-dimethylthiazole, thiazole, 2-isobutyl-4,5-dimethyl.
Can 4,5-Dimethyl-2-isobutylthiazole be labeled natural?
Nature occurrence: Not yet found in nature (provisional).
Nature occurrence has not been settled for this substance, so the natural or artificial class is not stated here. The FEMA GRAS status does not depend on it.
Regulatory status, with citations
United States
4,5-Dimethyl-2-isobutylthiazole is FEMA GRAS under FEMA number 4647. 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 15.078, Annex I Part A under Regulation (EC) 1334/2008, evaluation status approved (EFSA). The UK retains the same list.
JECFA (WHO / FAO)
JECFA number 2109, evaluated at the 76th meeting in 2012. 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. 4,5-Dimethyl-2-isobutylthiazole appears on the EPA Toxic Substances Control Act Chemical Substance Inventory under CAS 53498-32-1, where EPA names it Thiazole, 4,5-dimethyl-2-(2-methylpropyl)-.
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: Earthy, nutty, roasted, savory, meaty.
Where it is used
4,5-Dimethyl-2-isobutylthiazole is used in savory snacks, seasonings, meat products and soups, typically as a savory note.
Structurally similar flavor ingredients
Flavor ingredients with a GRAS determination closest to 4,5-Dimethyl-2-isobutylthiazole by structure. Whether one can replace it is a sensory and regulatory call; the reformulation tool works that through.
| Material | FEMA | Similarity | Occurrence |
|---|---|---|---|
| 2-Isobutyl-4,5-dimethyloxazole | 4397 | 79% | In nature |
| (+/-)-Ethyl 3-mercapto-2-methylbutanoate | 4392 | 62% | In nature |
| 5-Ethyl-2-methylpyridine | 3546 | 60% | In nature |
| 2-Isobutylthiazole | 3134 | 60% | In nature |
| 4,5-Dimethyl-2-propyloxazole | 4396 | 60% | In nature |
More thiazoles in this index
2,4,5-Trimethylthiazole · 4-Methyl-5-vinylthiazole · 2-Propionylthiazole · 2-Isobutylthiazole · 2-Ethyl-2,5-dihydro-4-methylthiazole · 2,4-Dimethyl-5-vinylthiazole
4,5-Dimethyl-2-isobutylthiazole FAQ
Is 4,5-Dimethyl-2-isobutylthiazole FEMA GRAS?
Yes. The FEMA Expert Panel lists 4,5-Dimethyl-2-isobutylthiazole as GRAS under FEMA number 4647. The Code of Federal Regulations lists it at 21 CFR 172.515.
What are the FEMA and CAS numbers for 4,5-Dimethyl-2-isobutylthiazole?
4,5-Dimethyl-2-isobutylthiazole is FEMA 4647, CAS 53498-32-1. Its flavor category is savory.
How is 4,5-Dimethyl-2-isobutylthiazole described, and where does it show up?
Flavorists describe 4,5-Dimethyl-2-isobutylthiazole as earthy, nutty, roasted, savory, meaty. It is used in savory snacks, seasonings, meat products and soups.
What did JECFA conclude about 4,5-Dimethyl-2-isobutylthiazole?
JECFA evaluated 4,5-Dimethyl-2-isobutylthiazole at the 76th meeting in 2012 under JECFA number 2109. The panel concluded: No safety concern at current levels of intake when used as a flavouring agent.
Is 4,5-Dimethyl-2-isobutylthiazole on the EU Union List?
Yes. FL 15.078 is the Union List entry for 4,5-Dimethyl-2-isobutylthiazole, annex I Part A, under Regulation 1334/2008, and the UK keeps the same list.
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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 4,5-DIMETHYL-2-ISOBUTYLTHIAZOLE under CAS 53498-32-1 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.