Flavor ingredient regulatory record
dl-Isoleucine
dl-Isoleucine is an amino acid in the nutty family, FEMA GRAS under FEMA number 3295 (CAS 443-79-8). Its odor is nutty, savory, earthy, protein-like.
- FEMA
- 3295
- CAS
- 443-79-8
- JECFA
- 1422
- EU FL
- 17.010
- Formula
- C6H13NO2
- EC
- 207-139-8
GRAS status: FEMA GRAS, publication 5. Recorded by FDA in the Substances Added to Food inventory under CAS 443-79-8.
Structure
Identity
Also known as: Isoleucine, Isoleucine, DL-, (±)-Isoleucine, DL-Ile, NSC 9958, 2-amino-3-methylpentanoic acid, h-dl-allo-ile-oh, 2-amino-3-methyl-pentanoic acid, isoleucine, dl-, dl-2-amino-3-methylpentanoic acid, isoleucine, allo-, isoleucine, threo-.
Can dl-Isoleucine be labeled natural?
The process decides for dl-Isoleucine. It occurs in nature, so a natural-source, natural-process material is natural flavor in the US and synthetic dl-Isoleucine 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
dl-Isoleucine is FEMA GRAS under FEMA number 3295. 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 17.010, Annex I Part A under Regulation (EC) 1334/2008, evaluation status approved (EFSA). The UK retains the same list.
JECFA (WHO / FAO)
JECFA number 1422, evaluated at the 63rd meeting in 2004. 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. dl-Isoleucine appears on the EPA Toxic Substances Control Act Chemical Substance Inventory under CAS 443-79-8, where EPA names it Isoleucine.
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: Nutty, savory, earthy, protein-like.
Where it is used
dl-Isoleucine is used in savory dishes, snack foods, protein supplements and seasonings, typically as a nutty note.
Structurally similar flavor ingredients
Flavor ingredients with a GRAS determination closest to dl-Isoleucine by structure. Whether one can replace it is a sensory and regulatory call; the reformulation tool works that through.
| Material | FEMA | Similarity | Occurrence |
|---|---|---|---|
| Leucine | 3297 | 93% | In nature |
| 3-Methyl-2-oxopentanoic acid | 3870 | 87% | In nature |
| l-Valine | 3444 | 87% | In nature |
| Methyl-3-pentenoic acid | 3464 | 86% | In nature |
| L-Threonine | 4710 | 78% | In nature |
More amino acids in this index
l-Valine · L-Arginine · L-Ornithine monochlorohydrate · Alanine · L-Methionylglycine · L-Alanyl-L-Glutamine
dl-Isoleucine FAQ
Does dl-Isoleucine have FEMA GRAS status?
dl-Isoleucine holds FEMA GRAS status under FEMA number 3295. The Code of Federal Regulations lists it at 21 CFR 172.515.
How do I cite dl-Isoleucine by FEMA or CAS number?
Cite dl-Isoleucine as FEMA 3295 or CAS 443-79-8; both point to the same entry. Its flavor category is nutty.
What does dl-Isoleucine smell and taste like, and where is it used?
The odor of dl-Isoleucine is nutty, savory, earthy, protein-like. Typical uses are savory dishes, snack foods, protein supplements and seasonings.
What did JECFA conclude about dl-Isoleucine?
JECFA evaluated dl-Isoleucine at the 63rd meeting in 2004 under JECFA number 1422. The panel concluded: No safety concern at current levels of intake when used as a flavouring agent.
Can dl-Isoleucine be used in the EU and UK?
Yes. FL 17.010 is the Union List entry for dl-Isoleucine, annex I Part A, under Regulation 1334/2008, and the UK keeps the same list.
Can dl-Isoleucine be labeled a natural flavor?
Nature makes dl-Isoleucine, which is why the US label turns on process. A natural route gives natural flavor; synthesis gives artificial dl-Isoleucine, same molecule. The EU and UK follow the same logic without a middle class; Mercosur and Mexico label synthetic dl-Isoleucine 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 DL-ISOLEUCINE under CAS 443-79-8 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.