About
Artificial butter flavour is a synthetic or nature-identical flavouring compound, with diacetyl (2,3-butanedione) as its primary active constituent, used to impart a characteristic buttery aroma and taste to foods such as microwave popcorn, margarine, baked goods, and dairy products. It is a volatile yellow liquid alpha-diketone also produced naturally during fermentation in butter, wine, beer, and dairy products.
Safety summary
Oral ingestion of diacetyl at typical food-use levels is classified GRAS by the FDA and presents no established risk to the general adult population. However, inhalation of diacetyl vapours—primarily an occupational concern—has been strongly linked to bronchiolitis obliterans ('popcorn lung'), a rare and irreversible obstructive lung disease documented in microwave popcorn factory workers. Emerging in-vitro research has raised preliminary concerns about diacetyl's ability to cross the blood-brain barrier and interact with amyloid peptides, but this has not been confirmed as a dietary risk for general consumers.
Regulatory landscape
| Jurisdiction | Status | Note |
|---|---|---|
| FSSAI (Food Safety and Standards Authority of India) (India) | Restricted | Diacetyl is permitted by FSSAI as a flavouring substance in table margarine and fat spread at a maximum level of 4 mg/kg. Artificial flavouring substances must be declared on labels under FSSAI Labelling & Display Regulations.source |
| EFSA (European Food Safety Authority) (European Union) | Approved | Diacetyl is regulated as a flavouring substance under Regulation (EC) No 1334/2008 on flavourings used in or on foods. It does not carry a dedicated E-number as a standalone food additive. EFSA's FAF Panel evaluates flavouring substances for safety prior to EU authorisation. No specific maximum use level has been established for diacetyl under the flavourings regulation; use is subject to good manufacturing practice (GMP).source |
| FDA (Food and Drug Administration) (United States) | Approved | Diacetyl is GRAS as a direct food additive under 21 CFR 184.1278. GRAS status applies to ingestion only; NIOSH has separately established occupational inhalation exposure limits for workers. The substitute flavouring 2,3-pentanedione (acetyl propionyl) is also GRAS per 21 CFR 172.515 but has similarly demonstrated respiratory toxicity via inhalation.source |
Who should approach with care
Research citations
- 1PubMed. Not Just an Aroma Compound: Expanding Perspectives on Diacetyl in Food Systems and Human Health, 2026. pmc.ncbi.nlm.nih.gov
- 2PubMed. Current perspective on amyloid aggregation accelerating properties of the artificial butter flavoring, diacetyl, 2024. pmc.ncbi.nlm.nih.gov
- 3PubMed. Models of Toxicity of Diacetyl and Alternative Diones, 2017. pmc.ncbi.nlm.nih.gov
- 4PubMed. Occupational Lung Disease Risk and Exposure to Butter-Flavoring Chemicals After Implementation of Controls at a Microwave Popcorn Plant, 2011. pmc.ncbi.nlm.nih.gov
- 5PubMed. Evaluation of the butter flavoring chemical diacetyl and a fluorochemical paper additive for mutagenicity and toxicity using the mammalian cell gene mutation assay in L5178Y mouse lymphoma cells, 2008. pubmed.ncbi.nlm.nih.gov
- 6NTP / NIOSH. Artificial Butter Flavoring and Constituents Diacetyl [CAS No. 431-03-8] and Acetoin [CAS No. 513-86-0]: Supporting Nomination for Toxicological Evaluation, 2007.
