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

1. Identity & Chemical Information

• Common Name(s): Diacetyl
• IUPAC Name: Butane-2,3-dione
• CAS Number: 431-03-8
• 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, characterized by two carbonyl groups. Its structure contributes to its buttery aroma, which is a key odor characteristic.

Citation hooks: FlavScents; PubChem; FEMA

2. Sensory Profile

• Odor and Flavor Descriptors: Diacetyl is known for its strong buttery aroma and flavor, often described as creamy, rich, and reminiscent of dairy products. It has a high intensity and diffusion, making it a prominent impact note in formulations.
• Taste and/or Odor Thresholds: The odor threshold for diacetyl is very low, typically around 0.1 ppm, which allows it to be perceived even at minimal concentrations.
• Typical Sensory Role: Diacetyl is primarily used as an impact note to impart a buttery flavor and aroma, enhancing the richness and creaminess of food products.

Citation hooks: FlavScents; peer-reviewed sensory literature

3. Natural Occurrence & Formation

• Known Natural Sources: Diacetyl occurs naturally in various fermented products, including butter, beer, and wine. It is also found in coffee and some fruits.
• Formation Pathways: It is primarily formed through fermentation processes, such as the Maillard reaction and enzymatic degradation of carbohydrates during the fermentation of dairy and alcoholic beverages.
• Relevance to “Natural Flavor” or “Natural Fragrance” Designation: Diacetyl can be labeled as a natural flavor when derived from natural 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 products to enhance buttery flavors. It is also used in microwave popcorn and margarine.
• 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 0.4 ppm, with higher concentrations used in specific applications like popcorn.
• Stability Considerations: Diacetyl is relatively stable under normal conditions but can degrade under high heat and 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 compared to flavors, but it can be found in gourmand and dairy-themed fragrance compositions.
• Functional Role: It serves as a trace realism note, adding a creamy, buttery nuance to fragrance blends.
• 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, contributing 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 recognized as GRAS (Generally Recognized As Safe) by FEMA for use in food flavors.
• European Union (Reg. (EC) No 1334/2008; FL number status): Approved for use as a flavoring substance under the EU regulation.
• United Kingdom (Post-Brexit Alignment or Divergence): Aligns with EU regulations, allowing its use as a flavoring agent.
• Asia (Japan, China, ASEAN): Generally permitted in food flavors, but specific regulations may vary by country.
• Latin America (e.g., Brazil, MERCOSUR): Typically allowed in food flavor applications, subject to regional regulatory frameworks.

Citation hooks: FEMA; EFSA; national authority publications

7. Toxicology, Safety & Exposure Considerations

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

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, enhancing the sensory appeal of various food products.
• Typical Synergies: Works well with other dairy flavors and can enhance the creaminess of vanilla and caramel notes.
• Common Formulation Pitfalls: Overuse can lead to an overpowering flavor, and care must be taken to avoid excessive concentrations.
• Situations Where It is Frequently Over- or Under-Used: Often overused in attempts to achieve a strong buttery note, leading to potential off-flavors.

Citation hooks: FlavScents; industry practice

9. Confidence & Data Quality Notes

• Well-Established Data: Extensive research and regulatory evaluations support the use of diacetyl in food flavors.
• Industry-Typical but Undocumented Practices: Use levels and applications are well-documented in industry literature, though some practices may vary.
• Known Data Gaps or Regulatory Ambiguities: Inhalation safety remains a concern, with ongoing research into occupational exposure risks.

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 2026-08-17 13:01:32 GMT (p2)