Flavor ingredient regulatory record
3,5-Undecadien-2-one
3,5-Undecadien-2-one is a ketone in the fruity family, FEMA GRAS under FEMA number 4746 (CAS 68973-20-6). Its odor is fruity, sweet, creamy, floral.
- FEMA
- 4746
- CAS
- 68973-20-6
- JECFA
- 2219
- Formula
- C11H18O
GRAS status: FEMA GRAS. Source: FEMA Flavor Ingredient Library.
Structure
Identity
Also known as: 3,5-undecadien-2-one, (3e,5e)-, undeca-3,5-dien-2-one, (3e,5e)-, undeca-3,5-dien-2-one, (3e,5e)-undeca-3,5-dien-2-one, 5-undecadien-2-one.
Can 3,5-Undecadien-2-one 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
3,5-Undecadien-2-one is FEMA GRAS under FEMA number 4746. It is cited in the Code of Federal Regulations at 21 CFR 172.515.
European Union and United Kingdom
No EU FL number is on file for 3,5-Undecadien-2-one. That is not a finding either way. The Union List covers defined flavouring substances, so natural complex materials are handled as flavouring preparations under Parts B to F and never receive a number, and substances used as additives sit under Regulation 1333/2008 instead. Confirm the position before EU or UK use.
JECFA (WHO / FAO)
JECFA number 2219.
Other US flags
Not on the California Proposition 65 list.
TSCA Inventory status
A flavor ingredient is also an industrial chemical. 3,5-Undecadien-2-one appears on the EPA Toxic Substances Control Act Chemical Substance Inventory under CAS 68973-20-6, where EPA names it 3,5-Undecadien-2-one.
Inactive in US commerce
EPA designates this substance inactive, so a Notice of Activity Form B is required before anyone manufactures or processes it again. Being FEMA GRAS does not change that. 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: Fruity, sweet, creamy, floral.
Where it is used
3,5-Undecadien-2-one is used in beverage, confection, flavoring, bakery and dairy, typically as a fruity note.
Structurally similar flavor ingredients
Flavor ingredients with a GRAS determination closest to 3,5-Undecadien-2-one by structure. Whether one can replace it is a sensory and regulatory call; the reformulation tool works that through.
| Material | FEMA | Similarity | Occurrence |
|---|---|---|---|
| 3-Decen-2-one | 3532 | 95% | In nature |
| 2-trans,4-trans-Decadienal | 3135 | 94% | In nature |
| (2E, 4E)-undeca-2,4-dienal | 3422 | 93% | In nature |
| 3-Nonen-2-one | 3955 | 93% | In nature |
More ketones in this index
4-Methylheptan-3-one · 2-Nonanone propyleneglycol acetal · 2-cyclohexenone · Methyl beta-naphthyl ketone · 3,4-Dimethyl-1,2-cyclo-pentanedione · 2-Acetyl-4-isopropylpyridine
3,5-Undecadien-2-one FAQ
Is 3,5-Undecadien-2-one FEMA GRAS?
Yes. The FEMA Expert Panel lists 3,5-Undecadien-2-one as GRAS under FEMA number 4746. It is also codified at 21 CFR 172.515.
What are the FEMA and CAS numbers for 3,5-Undecadien-2-one?
3,5-Undecadien-2-one is FEMA 4746, CAS 68973-20-6. FEMA files it in the fruity flavor category.
Is 3,5-Undecadien-2-one approved in the EU?
No EU FL number is on file for 3,5-Undecadien-2-one. It has a JECFA evaluation (JECFA 2219), which the EU list draws on, but the Union List entry itself should be confirmed before EU use.
Has JECFA evaluated 3,5-Undecadien-2-one?
Yes. JECFA number 2219.
How is 3,5-Undecadien-2-one described, and where does it show up?
Flavorists describe 3,5-Undecadien-2-one as fruity, sweet, creamy, floral. It is used in beverage, confection, flavoring, bakery and dairy.
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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 EPA TSCA Chemical Substance Inventory, matched on CAS 68973-20-6.
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.