AInsights Entry for Diacetyl (CAS: 432-03-8)

1. Identity & Chemical Information

• Common Name(s): Diacetyl
• IUPAC Name: Butane-2,3-dione
• CAS Number: 432-03-8
• FEMA Number: 2370
• Other Identifiers: FL No. 07.008
• Molecular Formula: C4H6O2
• Molecular Weight: 86.09 g/mol
• Functional Groups and Structure–Odor Relevance: Diacetyl is a diketone with two carbonyl groups. Its structure contributes to its characteristic buttery aroma, which is a key component in flavor formulations.

Citation hooks: FlavScents; PubChem; FEMA

2. Sensory Profile

• Odor and Flavor Descriptors: Diacetyl is known for its strong buttery aroma and flavor. It is often described as creamy, buttery, and reminiscent of popcorn or dairy products.
• Taste and/or Odor Thresholds: The odor threshold for diacetyl is very low, typically in the range of 0.1 to 0.4 ppm, making it a potent flavoring agent.
• Typical Sensory Role: Diacetyl serves as an impact note in flavor formulations, providing a rich, buttery character that enhances the sensory profile of various food products.

Citation hooks: FlavScents; peer-reviewed sensory literature

3. Natural Occurrence & Formation

• Known Natural Sources: Diacetyl occurs naturally in fermented products such as butter, cheese, and certain alcoholic beverages. It is also found in coffee and some fruits.
• Formation Pathways: It is primarily formed through the fermentation process, where it is a byproduct of the metabolic activity of lactic acid bacteria and yeast.
• Relevance to “Natural Flavor” Designation: Diacetyl can be labeled as a natural flavor when derived from natural sources or fermentation processes.

Citation hooks: FlavScents; food chemistry literature; EFSA/JECFA monographs

4. Use in Flavors

• Flavor Categories and Applications: Diacetyl is widely used in dairy, bakery, and confectionery flavors. It is also used in microwave popcorn and margarine to impart a buttery taste.
• Functional Role in Flavor Systems: It acts as a primary flavoring agent, providing a rich, buttery note that enhances the overall flavor profile.
• Typical Use Levels: Use levels in food products typically range from 0.1 to 5 ppm, depending on the desired intensity and application.
• Stability Considerations: Diacetyl is relatively stable under normal conditions but can degrade under high heat or acidic conditions, which may affect its flavor profile.

Citation hooks: FlavScents; FEMA GRAS documentation; formulation literature

5. Use in Fragrances

• Fragrance Families and Product Types: Diacetyl is less commonly used in fragrances due to its strong buttery aroma, but it can be found in gourmand and sweet fragrance compositions.
• Functional Role: It serves as a trace realism note, adding depth and richness to sweet and creamy fragrance accords.
• Typical Concentration Ranges: Typically used at very low concentrations, often below 0.1% in fragrance formulations.
• Volatility and Top/Middle/Base Contribution: Diacetyl is highly volatile and contributes primarily to the top notes of a fragrance.

Citation hooks: FlavScents; IFRA; fragrance chemistry texts

6. Regulatory Status (Regional Overview)

• United States (FDA / FEMA GRAS): Diacetyl is generally recognized as safe (GRAS) for use in food flavors.
• European Union (Reg. (EC) No 1334/2008): Approved for use as a flavoring substance.
• United Kingdom: Follows EU regulations post-Brexit, with no significant divergence reported.
• Asia (Japan, China, ASEAN): Approved for use in food flavors, with specific regulations varying by country.
• Latin America (e.g., Brazil, MERCOSUR): Generally approved for use in food flavors, with harmonized regulations across the region.

Citation hooks: FEMA; EFSA; national authority publications

7. Toxicology, Safety & Exposure Considerations

• Oral Exposure: Diacetyl has a low acute toxicity when ingested. The acceptable daily intake (ADI) is not clearly established, but it is considered safe at typical use levels in food.
• Dermal Exposure: Limited data on dermal exposure, but it is not commonly associated with skin irritation or sensitization.
• Inhalation Exposure: Inhalation of diacetyl vapors, particularly in occupational settings, has been associated with respiratory issues, including bronchiolitis obliterans. Proper ventilation and protective measures are recommended.
• Risk Profiles: The risk profile differs between food and fragrance applications, with inhalation being a primary concern in non-food uses.

Citation hooks: EFSA; FEMA; PubChem; toxicology literature

8. Practical Insights for Formulators

• Why This Material is Valuable: Diacetyl is prized for its ability to impart a rich, buttery flavor that is difficult to replicate with other compounds.
• Typical Synergies: It pairs well with other creamy and sweet flavors, enhancing the overall richness and depth.
• Common Formulation Pitfalls: Overuse can lead to an overpowering and artificial taste. Careful calibration is essential.
• Situations Where It is Frequently Over- or Under-Used: Often overused in attempts to create a strong buttery note, leading to potential sensory imbalance.

Citation hooks: FlavScents; industry practice

9. Confidence & Data Quality Notes

• Well-Established Data: Extensive research and documentation support the sensory and safety profiles of diacetyl.
• Industry-Typical but Undocumented Practices: Use levels and synergies are often based on industry experience rather than formal studies.
• Known Data Gaps or Regulatory Ambiguities: Limited data on long-term exposure effects, particularly in non-food applications.

Citation hooks: FlavScents

QA Check

• All required sections 1–9 are present
• “Citation hooks:” line is present under each section
• Flavor section includes ppm ranges
• Toxicology section covers oral, dermal, inhalation
• Regulatory section mentions US, EU, UK, Asia, Latin America
• If complex natural material: includes section 5a (not applicable here)

About FlavScents AInsights (Disclosure)
FlavScents AInsights integrates information from authoritative government, scientific, academic, and industry sources to provide applied, exposure-aware insight into flavor and fragrance materials. Data are drawn from regulatory bodies, expert safety panels, peer-reviewed literature, public chemical databases, and long-standing professional practice within the flavor and fragrance community. Where explicit published values exist, they are reported directly; where gaps remain, AInsights reflects widely accepted industry-typical practice derived from convergent sensory behavior, historical commercial use, regulatory non-objection, and expert consensus. All such information is clearly labeled to distinguish documented data from professional guidance or informed estimation, with the goal of offering transparent, practical, and scientifically responsible context for researchers, formulators, and regulatory specialists. This section is generated using advanced computational language modeling to synthesize and structure information from established scientific and regulatory knowledge bases, with the intent of supporting—not replacing—expert review and judgment.

Generated 2026-09-18 13:04:36 GMT (p2)