FlavScents AInsights Entry for 2-Hexenal (CAS: 505-57-7)

1. Identity & Chemical Information

• Common Name(s): 2-Hexenal, Hex-2-enal
• IUPAC Name: (E)-hex-2-enal
• CAS Number: 505-57-7
• FEMA Number: 3429
• Other Identifiers: FL No. 05.061
• Molecular Formula: C6H10O
• Molecular Weight: 98.15 g/mol

2-Hexenal is an α,β-unsaturated aldehyde characterized by its functional groups, which include an aldehyde group and a double bond. The presence of these groups contributes to its distinctive green, leafy odor, often associated with freshly cut grass or unripe fruits. The structure-odor relationship is significant, as the conjugated system enhances its reactivity and sensory impact.

Citation hooks: FlavScents; PubChem; FEMA

2. Sensory Profile

2-Hexenal is known for its strong, green, and leafy odor, reminiscent of freshly cut grass or green apples. It is often described as having a high intensity and moderate diffusion, making it a potent impact note in both flavors and fragrances. The odor threshold of 2-hexenal is relatively low, allowing it to be perceived at minimal concentrations. It is typically used as an impact note to impart freshness and realism to formulations.

Citation hooks: FlavScents; peer-reviewed sensory literature

3. Natural Occurrence & Formation

2-Hexenal naturally occurs in a variety of fruits and vegetables, including apples, tomatoes, and green beans. It is formed through enzymatic degradation of fatty acids, particularly linoleic acid, during plant tissue damage. This compound is significant in the context of "natural flavor" designation, as it is a naturally occurring component in many plant-derived foods.

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

4. Use in Flavors

2-Hexenal is widely used in flavor formulations, particularly in fruit and vegetable profiles. It serves as an impact note, providing a fresh, green character to apple, pear, and tomato flavors. Typical use levels in finished food products range from 0.1 to 5 ppm, depending on the desired intensity and application. It is relatively stable under acidic conditions but can be prone to oxidation, which may affect its sensory properties.

Citation hooks: FlavScents; FEMA GRAS documentation; formulation literature

5. Use in Fragrances

In fragrance applications, 2-hexenal is utilized for its fresh, green, and leafy notes. It is commonly found in green, floral, and fruity fragrance families, contributing as a top note due to its high volatility. Typical concentrations in fragrance formulations range from trace amounts to 0.5%, depending on the desired effect and product type.

Citation hooks: FlavScents; IFRA; fragrance chemistry texts

6. Regulatory Status (Regional Overview)

• United States: Recognized as GRAS by FEMA for flavor use.
• European Union: Listed under Regulation (EC) No 1334/2008 with FL No. 05.061.
• United Kingdom: Aligns with EU regulations post-Brexit.
• Asia: Approved for use in Japan and China, with specific concentration limits.
• Latin America: Generally accepted in MERCOSUR countries, with harmonized assumptions.

Explicit approvals and harmonized assumptions are prevalent, though specific concentration limits may vary by country.

Citation hooks: FEMA; EFSA; national authority publications

7. Toxicology, Safety & Exposure Considerations

For oral exposure, 2-hexenal is considered safe at typical flavor use levels, with a high margin of safety. Dermal exposure in fragrance applications may pose a risk of irritation or sensitization, particularly at higher concentrations. Inhalation exposure is generally low risk due to its rapid volatilization, but occupational exposure should be monitored. Risk profiles differ slightly between food and fragrance applications, with dermal considerations being more prominent in the latter.

Citation hooks: EFSA; FEMA; PubChem; toxicology literature

8. Practical Insights for Formulators

2-Hexenal is valued for its ability to impart a fresh, green character to both flavors and fragrances. It synergizes well with other green and fruity notes, enhancing the overall freshness of a formulation. Common pitfalls include overuse, which can lead to an overpowering or harsh sensory profile. It is often under-used in complex formulations where subtlety is required.

Citation hooks: FlavScents; industry practice

9. Confidence & Data Quality Notes

Data on 2-hexenal is well-established, with comprehensive sensory and regulatory information available. Industry practices are well-documented, though some variability in natural occurrence data exists due to differences in plant sources and processing methods.

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 2026-03-04 15:55:53 GMT (p2)