Flavor ingredient regulatory record
Propylene glycol mono- and diesters of fatty acids
Propylene glycol mono- and diesters of fatty acids is a natural complex flavoring material in the sweet family, FEMA GRAS under FEMA number 4208 (CAS 1323-39-3). Its odor is sweet, creamy, buttery, fatty.
- FEMA
- 4208
- CAS
- 1323-39-3
- EC
- 215-354-3
GRAS status: FEMA GRAS, publication 22. Recorded by FDA in the Substances Added to Food inventory under CAS 977050-70-6.
Structure
Material
Propylene glycol mono- and diesters of fatty acids is a natural complex material rather than a single molecule, so it has no one structure. FEMA lists it as Propylene glycol mono- and diesters of fatty acids.
Identity
Also known as: Octadecanoic acid, monoester with 1,2-propanediol, Stearic acid, monoester with 1,2-propanediol, Stearic acid, ester with 1,2-propanediol, 1,2-Propanediol, monostearate, Crill 26, Nonex 32, Cerasynt PA, Cerasynt PN, Dragil P, Emcol PS 50RHP, Monosteol, Monosteol TG.
Can Propylene glycol mono- and diesters of fatty acids be labeled natural?
Propylene glycol mono- and diesters of fatty acids occurs in nature, so the label depends on the route: propylene glycol mono- and diesters of fatty acids won from a natural source by a physical, enzymatic or microbiological process is natural flavor in the United States, and synthesized propylene glycol mono- and diesters of fatty acids is artificial. The EU and UK follow the same logic without a middle class; Mercosur and Mexico label synthetic propylene glycol mono- and diesters of fatty acids 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
Propylene glycol mono- and diesters of fatty acids is FEMA GRAS under FEMA number 4208. It is cited in the Code of Federal Regulations at 21 CFR 172.856.
European Union and United Kingdom
No EU FL number is on file for Propylene glycol mono- and diesters of fatty acids. 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)
Propylene glycol mono- and diesters of fatty acids has not been evaluated by JECFA as a flavouring agent, or no evaluation is on file.
Other US flags
Not on the California Proposition 65 list.
TSCA Inventory status
A flavor ingredient is also an industrial chemical. Propylene glycol mono- and diesters of fatty acids appears on the EPA Toxic Substances Control Act Chemical Substance Inventory under CAS 1323-39-3, where EPA names it Octadecanoic acid, monoester with 1,2-propanediol.
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: Sweet, creamy, buttery, fatty.
Taste: Mild, sweet, fatty.
Where it is used
Propylene glycol mono- and diesters of fatty acids is used in baked goods, confection, dairy, creams and emulsifiers, typically as a sweet note.
More esters in this index
Polyglycerol esters of fatty acids · Propylene glycol stearate · Sucrose monopalmitate · Ethyl 5-(methylthio)pentanoate · Phenethyl isovalerate · Ethyl 3-oxohexanoate
Propylene glycol mono- and diesters of fatty acids FAQ
Is propylene glycol mono- and diesters of fatty acids on the FEMA GRAS list?
It is. FEMA number 4208 covers propylene glycol mono- and diesters of fatty acids. It is also codified at 21 CFR 172.856.
What is the FEMA number for propylene glycol mono- and diesters of fatty acids?
The FEMA number for propylene glycol mono- and diesters of fatty acids is 4208 and its CAS registry number is 1323-39-3. FEMA files it in the sweet flavor category.
Is propylene glycol mono- and diesters of fatty acids natural or artificial?
Since propylene glycol mono- and diesters of fatty acids is found in nature, US labeling follows how it was obtained: natural flavor from a natural source and a natural process, artificial when propylene glycol mono- and diesters of fatty acids is synthesized. The EU and UK follow the same logic without a middle class; Mercosur and Mexico label synthetic propylene glycol mono- and diesters of fatty acids identical-to-natural.
What is propylene glycol mono- and diesters of fatty acids used for?
Propylene glycol mono- and diesters of fatty acids is described as sweet, creamy, buttery, fatty. On the palate it is mild, sweet, fatty. It shows up in baked goods, confection, dairy, creams and emulsifiers.
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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 PROPYLENE GLYCOL MONO- AND DIESTERS OF FATS AND FATTY ACIDS under CAS 977050-70-6 and carries its FEMA number and its 21 CFR citations. The inventory is searchable at FDA. FDA records its technical effect as emulsifier or emulsifier salt, stabilizer or thickener.
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.