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: 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 characterized by its diketone structure, which is crucial for its buttery aroma. The presence of two carbonyl groups contributes to its high reactivity and distinctive odor profile.

Citation hooks: FlavScents; PubChem; FEMA

2. Sensory Profile

Diacetyl is renowned for its rich, buttery aroma and flavor, often described as reminiscent of butter, cream, and cheese. It is a potent compound with a low odor threshold, making it an impactful note even at low concentrations. Its sensory role is primarily as an impact note, providing a creamy, buttery character to flavor formulations.

Citation hooks: FlavScents; peer-reviewed sensory literature

3. Natural Occurrence & Formation

Diacetyl naturally occurs in various fermented products, including butter, beer, and wine, as a byproduct of fermentation processes. It is formed through the metabolic pathways of lactic acid bacteria and yeast, particularly during the fermentation of sugars. Diacetyl's presence in natural products allows it to be designated as a "natural flavor" in certain contexts.

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

4. Use in Flavors

Diacetyl is extensively used in dairy flavor formulations, particularly in butter, cheese, and cream flavors. It serves as a key impact note, enhancing the richness and authenticity of these flavors. Typical use levels in food range from 0.1 to 5 ppm, with higher concentrations potentially leading to an overpowering or artificial taste. Diacetyl is sensitive to heat and oxidation, which can affect its stability in formulations.

Citation hooks: FlavScents; FEMA GRAS documentation; formulation literature

5. Use in Fragrances

In fragrances, diacetyl is used sparingly due to its potent aroma. It is primarily employed in gourmand and dairy-themed fragrance compositions, where it acts as a trace realism note. Its volatility classifies it as a top note, contributing to the initial impression of a fragrance. Typical concentrations are low, often below 0.1%, to prevent overwhelming the fragrance profile.

Citation hooks: FlavScents; IFRA; fragrance chemistry texts

6. Regulatory Status (Regional Overview)

• United States: Diacetyl is FEMA GRAS approved for flavor use.
• European Union: Approved under Regulation (EC) No 1334/2008 with FL number 07.008.
• United Kingdom: Follows EU regulations post-Brexit.
• Asia: Japan and China have specific guidelines for diacetyl use in flavors.
• Latin America: Generally aligns with international standards, but specific regulations may vary.

Explicit approvals exist for flavor use, with harmonized assumptions across regions. However, there are known uncertainties regarding its use in fragrances due to potential safety concerns.

Citation hooks: FEMA; EFSA; national authority publications

7. Toxicology, Safety & Exposure Considerations

• Oral Exposure: Diacetyl has an established ADI, but specific values are not clearly reported. It is generally considered safe at typical flavor use levels.
• Dermal Exposure: Known to cause irritation and sensitization; IFRA provides guidelines for its use in fragrances.
• Inhalation Exposure: Volatile nature raises concerns for occupational exposure, particularly in manufacturing settings.

Risk profiles differ between food and fragrance applications, with more stringent controls in place for inhalation exposure due to potential respiratory effects.

Citation hooks: EFSA; FEMA; PubChem; toxicology literature

8. Practical Insights for Formulators

Diacetyl is valued for its ability to impart a rich, buttery character to both flavors and fragrances. It synergizes well with other creamy and dairy notes but can easily dominate a formulation if overused. Formulators should be cautious of its stability issues and potential safety concerns, particularly in fragrance applications.

Citation hooks: FlavScents; industry practice

9. Confidence & Data Quality Notes

Data on diacetyl is well-established, particularly regarding its sensory characteristics and regulatory status. However, industry practices regarding its use in fragrances are less documented, and there are known data gaps in specific toxicological thresholds.

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 2026-07-02 07:05:28 GMT (p2)