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

1. Identity & Chemical Information

Diacetyl, also known as 2,3-butanedione, is a volatile organic compound with the CAS number 432-03-8. It is commonly used in the flavor and fragrance industry due to its distinctive buttery aroma. The IUPAC name for diacetyl is butane-2,3-dione. It has a molecular formula of C4H6O2 and a molecular weight of 86.09 g/mol. Diacetyl contains two ketone groups, which are responsible for its characteristic odor. The compound is identified by FEMA number 2370 and is also listed under various other identifiers such as FL number 07.008 and CoE number 02.007. The presence of the diketone functional group is crucial for its odor profile, contributing to its buttery and creamy scent, which is highly valued in flavor applications.

Citation hooks: FlavScents; PubChem; FEMA

2. Sensory Profile

Diacetyl is renowned for its strong buttery aroma, often described as creamy, rich, and reminiscent of dairy products like butter and cream. It is a high-impact compound with a low odor threshold, making it effective even at low concentrations. The compound is primarily used as an impact note in flavor formulations to impart a buttery character. Its diffusion is moderate, allowing it to blend well with other flavor components without overpowering them. Diacetyl is also used to enhance the perception of richness and fullness in flavor profiles, making it a popular choice in bakery, dairy, and confectionery applications.

Citation hooks: FlavScents; peer-reviewed sensory literature

3. Natural Occurrence & Formation

Diacetyl occurs naturally in various food products, including butter, cheese, and fermented beverages like beer and wine. It is formed through the fermentation process, particularly during the metabolic activities of lactic acid bacteria and yeast. The compound is a byproduct of the Maillard reaction, which occurs during the heating of sugars and amino acids. Diacetyl's presence in natural products allows it to be designated as a "natural flavor" under certain regulatory frameworks, provided it is derived from natural sources.

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

4. Use in Flavors

Diacetyl is extensively used in flavor formulations, particularly in dairy, bakery, and confectionery products. It serves as a key component in butter flavors and is often used to enhance the richness and creaminess of food products. Typical use levels in finished food products range from 0.1 to 5 ppm, with higher concentrations used in products where a pronounced buttery note is desired. Diacetyl is relatively stable under typical food processing conditions, but it 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

In the fragrance industry, diacetyl is used to impart a creamy, buttery note to various fragrance compositions. It is commonly found in gourmand and sweet fragrance families, where it acts as a modifier to enhance the richness and depth of the scent. Diacetyl is typically used in trace amounts due to its potent aroma, contributing primarily to the top and middle notes of a fragrance composition. Its volatility allows it to blend seamlessly with other fragrance components, providing a smooth and creamy background.

Citation hooks: FlavScents; IFRA; fragrance chemistry texts

6. Regulatory Status (Regional Overview)

In the United States, diacetyl is recognized as Generally Recognized As Safe (GRAS) by FEMA for use in food flavors. In the European Union, it is approved under Regulation (EC) No 1334/2008 and assigned the FL number 07.008. The United Kingdom follows similar regulations post-Brexit. In Asia, diacetyl is permitted in Japan and China, with specific use levels defined by local regulations. In Latin America, countries like Brazil and those in MERCOSUR have harmonized regulations allowing its use in food flavors. However, there are known uncertainties regarding its use in certain applications, particularly due to its potential health risks when inhaled.

Citation hooks: FEMA; EFSA; national authority publications

7. Toxicology, Safety & Exposure Considerations

Diacetyl has been associated with respiratory issues, particularly in occupational settings where inhalation exposure is significant. The compound is known to cause bronchiolitis obliterans, a serious lung condition, in workers exposed to high levels of diacetyl vapor. For oral exposure, diacetyl is considered safe at typical flavor use levels, with an Acceptable Daily Intake (ADI) established by regulatory authorities. Dermal exposure in fragrance applications is generally low risk, but formulations should comply with IFRA guidelines to prevent irritation or sensitization. The risk profiles differ significantly between food and fragrance applications, with inhalation being the primary concern in non-food uses.

Citation hooks: EFSA; FEMA; PubChem; toxicology literature

8. Practical Insights for Formulators

Diacetyl is a valuable compound for formulators due to its ability to impart a rich, buttery flavor or aroma. It synergizes well with other creamy and sweet notes, enhancing the overall sensory experience. However, formulators should be cautious of its potent aroma, as overuse can lead to an overpowering and artificial taste. It is often under-used in applications where a subtle buttery note is desired, as formulators may fear its strong impact. Proper balancing with other flavor or fragrance components is essential to achieve the desired profile.

Citation hooks: FlavScents; industry practice

9. Confidence & Data Quality Notes

The data on diacetyl is well-established, particularly regarding its sensory properties and regulatory status. Industry practices are well-documented, although some undocumented practices exist, particularly in fragrance applications. Known data gaps include specific inhalation exposure limits in non-occupational settings, which remain a regulatory ambiguity.

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 2026-02-12 18:11:59 GMT (p2)