Flavor ingredient regulatory record
4,5-Dimethyl-2-isobutyl-3-thiazoline
4,5-Dimethyl-2-isobutyl-3-thiazoline is a thiazoline in the savory family, FEMA GRAS under FEMA number 3621 (CAS 65894-83-9). Its odor is savory, meaty, earthy, umami.
- FEMA
- 3621
- CAS
- 65894-83-9
- JECFA
- 1045
- EU FL
- 15.032
- Formula
- C9H17NS
- EC
- 265-969-6
GRAS status: FEMA GRAS, publication 12. Recorded by FDA in the Substances Added to Food inventory under CAS 65894-83-9.
Structure
Identity
Also known as: Thiazole, 2,5-dihydro-4,5-dimethyl-2-(2-methylpropyl)-, 2,5-Dihydro-4,5-dimethyl-2-(2-methylpropyl)thiazole, 2-(2′-Methyl-n-propyl)-4,5-dimethyl-Δ3-thiazoline, 2-Isobutyl-4,5-dimethyl-2,5-dihydrothiazole, 2-isobutyl-4,5-dimethyl-3-thiazoline, 4,5-dimethyl-2-(2-methylpropyl)-2,5-dihydro-1,3-thiazole, 2,5-dihydro-4,5-dimethyl-2-(2-methylpropyl)thiazole, thiazole, 2,5-dihydro-4,5-dimethyl-2-(2-methylpropyl)-, 2-isobutyl-4,5-dimethyl thiazoline, 2,5-dihydro-2-isobutyl-4,5-dimethylthiazole, 3-thiazoline, 4,5-dimethyl-2-isobutyl-, yeast thiazoline.
Can 4,5-Dimethyl-2-isobutyl-3-thiazoline be labeled natural?
Nature makes 4,5-Dimethyl-2-isobutyl-3-thiazoline, which is why the US label turns on process. A natural route gives natural flavor; synthesis gives artificial 4,5-Dimethyl-2-isobutyl-3-thiazoline, same molecule. The EU and UK follow the same logic without a middle class; Mercosur and Mexico label synthetic 4,5-Dimethyl-2-isobutyl-3-thiazoline 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
4,5-Dimethyl-2-isobutyl-3-thiazoline is FEMA GRAS under FEMA number 3621. 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 15.032, Annex I Part A under Regulation (EC) 1334/2008, evaluation status approved (EFSA). The UK retains the same list.
JECFA (WHO / FAO)
JECFA number 1045, evaluated at the 59th meeting in 2002. 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-isobutyl-3-thiazoline appears on the EPA Toxic Substances Control Act Chemical Substance Inventory under CAS 65894-83-9, where EPA names it Thiazole, 2,5-dihydro-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: Savory, meaty, earthy, umami.
Where it is used
4,5-Dimethyl-2-isobutyl-3-thiazoline is used in savory snacks, seasonings, meat products and sauces, typically as a savory note.
Structurally similar flavor ingredients
Flavor ingredients with a GRAS determination closest to 4,5-Dimethyl-2-isobutyl-3-thiazoline by structure. Whether one can replace it is a sensory and regulatory call; the reformulation tool works that through.
| Material | FEMA | Similarity | Occurrence |
|---|---|---|---|
| cis- and trans-5-Ethyl-4-methyl-2-(2-methylpropyl)-thiazoline | 4319 | 93% | Not determined |
| 2-(2-Butyl)-4,5-dimethyl-3-thiazoline | 3619 | 87% | In nature |
| cis- and trans-5-Ethyl-4-methyl-2-(1-methylpropyl)-thiazoline | 4318 | 86% | Not determined |
| 4,5-Dimethyl-2-isobutylthiazole | 4647 | 69% | Not determined |
| 4,5-Dimethyl-2-ethyl-3-thiazoline | 3620 | 69% | In nature |
More thiazolines in this index
2-Acetyl-2-thiazoline · 4-Methyl-3-thiazoline · 4,5-Dimethyl-2-ethyl-3-thiazoline · cis- and trans-5-Ethyl-4-methyl-2-(1-methylpropyl)-thiazoline · 2-(2-Butyl)-4,5-dimethyl-3-thiazoline · cis- and trans-5-Ethyl-4-methyl-2-(2-methylpropyl)-thiazoline
4,5-Dimethyl-2-isobutyl-3-thiazoline FAQ
Is 4,5-Dimethyl-2-isobutyl-3-thiazoline FEMA GRAS?
Yes. The FEMA Expert Panel lists 4,5-Dimethyl-2-isobutyl-3-thiazoline as GRAS under FEMA number 3621. The Code of Federal Regulations lists it at 21 CFR 172.515.
What are the FEMA and CAS numbers for 4,5-Dimethyl-2-isobutyl-3-thiazoline?
4,5-Dimethyl-2-isobutyl-3-thiazoline is FEMA 3621, CAS 65894-83-9. Its flavor category is savory.
How is 4,5-Dimethyl-2-isobutyl-3-thiazoline described, and where does it show up?
Flavorists describe 4,5-Dimethyl-2-isobutyl-3-thiazoline as savory, meaty, earthy, umami. It is used in savory snacks, seasonings, meat products and sauces.
What did JECFA conclude about 4,5-Dimethyl-2-isobutyl-3-thiazoline?
JECFA evaluated 4,5-Dimethyl-2-isobutyl-3-thiazoline at the 59th meeting in 2002 under JECFA number 1045. The panel concluded: No safety concern at current levels of intake when used as a flavouring agent.
Is 4,5-Dimethyl-2-isobutyl-3-thiazoline on the EU Union List?
Yes. FL 15.032 is the Union List entry for 4,5-Dimethyl-2-isobutyl-3-thiazoline, annex I Part A, under Regulation 1334/2008, and the UK keeps the same list.
Does 4,5-Dimethyl-2-isobutyl-3-thiazoline count as natural in the US and the EU?
The process decides for 4,5-Dimethyl-2-isobutyl-3-thiazoline. It occurs in nature, so a natural-source, natural-process material is natural flavor in the US and synthetic 4,5-Dimethyl-2-isobutyl-3-thiazoline is artificial. The EU and UK follow the same logic without a middle class; Mercosur and Mexico label synthetic 4,5-Dimethyl-2-isobutyl-3-thiazoline 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 4,5-DIMETHYL-2-ISOBUTYL-3-THIAZOLINE under CAS 65894-83-9 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.