Flavor ingredient regulatory record
Nootkatone 50%
Nootkatone 50% is a flavoring substance, FEMA GRAS under FEMA number 4988 (CAS 4674-50-4). Its odor is grapefruit, citrus, orange, sweet peely with a woody nuance.
- FEMA
- 4988
- CAS
- 4674-50-4
- JECFA
- 1398
- EU FL
- 07.089
- Formula
- C15H22O
- EC
- 225-124-4
GRAS status: FEMA GRAS. Source: FEMA Flavor Ingredient Library.
Structure
Identity
Also known as: 2(3H)-Naphthalenone, 4,4a,5,6,7,8-hexahydro-4,4a-dimethyl-6-(1-methylethenyl)-, (4R,4aS,6R)-, 4βH,5α-Eremophila-1(10),11-dien-2-one, Nootkatone, 2(3H)-Naphthalenone, 4,4a,5,6,7,8-hexahydro-4,4a-dimethyl-6-(1-methylethenyl)-, [4R-(4α,4aα,6β)]-, (4R,4aS,6R)-4,4a,5,6,7,8-Hexahydro-4,4a-dimethyl-6-(1-methylethenyl)-2(3H)-naphthalenone, (+)-Nootkatone, Nootkanone, (4R,4AS,6R)-4,4a-dimethyl-6-(prop-1-en-2-yl)-4,4a,5,6,7,8-hexahydronaphthalen-2(3H)-one, nootkatone, (+)-nootkatone, (4r,4as,6r)-4,4a-dimethyl-6-prop-1-en-2-yl-3,4,5,6,7,8-hexahydronaphthalen-2-one, 1(10),11-eremophiladien-2-one.
Can Nootkatone 50% be labeled natural?
Nootkatone 50% occurs in nature, so the label depends on the route: Nootkatone 50% won from a natural source by a physical, enzymatic or microbiological process is natural flavor in the United States, and synthesized Nootkatone 50% is artificial. The EU and UK follow the same logic without a middle class; Mercosur and Mexico label synthetic Nootkatone 50% 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
Nootkatone 50% is FEMA GRAS under FEMA number 4988. 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 07.089, Annex I Part A under Regulation (EC) 1334/2008, evaluation status approved (EFSA). The UK retains the same list.
Purity. At least 93%; secondary component 3-4% dihydronootkatone
JECFA (WHO / FAO)
JECFA number 1398, evaluated at the 63rd meeting in 2004. no safety concern at current levels of intake.
Other US flags
Not on the California Proposition 65 list.
TSCA Inventory status
A flavor ingredient is also an industrial chemical. Nootkatone 50% appears on the EPA Toxic Substances Control Act Chemical Substance Inventory under CAS 4674-50-4, where EPA names it 2(3H)-Naphthalenone, 4,4a,5,6,7,8-hexahydro-4,4a-dimethyl-6-(1-methylethenyl)-, (4R,4aS,6R)-.
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: Grapefruit, citrus, orange, sweet peely with a woody nuance.
Taste: Grapefruit, citrus, orange and bitter.
Where it is used
Typical applications for Nootkatone 50% are not on file yet.
Structurally similar flavor ingredients
Flavor ingredients with a GRAS determination closest to Nootkatone 50% by structure. Whether one can replace it is a sensory and regulatory call; the reformulation tool works that through.
| Material | FEMA | Similarity | Occurrence |
|---|---|---|---|
| Nootkatone | 3166 | 99% | In nature |
| Dehydronootkatone | 4091 | 96% | In nature |
| Dihydronootkatone | 3776 | 95% | In nature |
| alpha-iso-Methylionone | 2714 | 78% | In nature |
| beta-Isomethylionone | 4151 | 77% | In nature |
Nootkatone 50% FAQ
Is Nootkatone 50% on the FEMA GRAS list?
It is. FEMA number 4988 covers Nootkatone 50%. It is also codified at 21 CFR 172.515.
What is the FEMA number for Nootkatone 50%?
The FEMA number for Nootkatone 50% is 4988 and its CAS registry number is 4674-50-4.
Is Nootkatone 50% natural or artificial?
Since Nootkatone 50% is found in nature, US labeling follows how it was obtained: natural flavor from a natural source and a natural process, artificial when Nootkatone 50% is synthesized. The EU and UK follow the same logic without a middle class; Mercosur and Mexico label synthetic Nootkatone 50% identical-to-natural.
Is Nootkatone 50% approved in the EU?
Nootkatone 50% is on the EU Union List of flavouring substances as FL 07.089 (Annex I Part A) under Regulation 1334/2008.
Has JECFA evaluated Nootkatone 50%?
Yes. JECFA number 1398, evaluated at the 63rd meeting in 2004. Conclusion: no safety concern at current levels of intake.
What is Nootkatone 50% used for?
Nootkatone 50% is described as grapefruit, citrus, orange, sweet peely with a woody nuance. On the palate it is grapefruit, citrus, orange and bitter.
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Guides: What Is FEMA GRAS? · Natural vs artificial · Filing a GRAS notification
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Sources and attribution. The FEMA number and GRAS status on this page name a conclusion reached by the Expert Panel of the Flavor and Extract Manufacturers Association of the United States. FDA does not list this substance by FEMA number in its Substances Added to Food inventory. Its identity is attested by FDA Substances Added to Food, EU Union List of flavouring substances, EPA TSCA Chemical Substance Inventory, matched on CAS 4674-50-4.
FEMA publishes its own entry for this substance in the FEMA Flavor Library, which is the authoritative record 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.