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. 05.062
• Molecular Formula: C6H10O
• Molecular Weight: 98.15 g/mol

2-Hexenal is an unsaturated aldehyde characterized by the presence of an α,β-unsaturated carbonyl group. This functional group is crucial for its reactivity and sensory properties, contributing to its distinctive green, leafy odor. The double bond configuration (E) is significant for its odor profile, influencing its use in flavor and fragrance applications.

Citation hooks: FlavScents; PubChem; FEMA

2. Sensory Profile

2-Hexenal is known for its strong, green, leafy odor reminiscent of freshly cut grass or unripe fruits. It is often described as having a sharp, penetrating aroma with moderate diffusion. The compound is used as an impact note in formulations, providing freshness and a natural green character. While specific taste and odor thresholds are not widely documented, its potent aroma suggests low threshold values, making it effective even at minimal concentrations.

Citation hooks: FlavScents; peer-reviewed sensory literature

3. Natural Occurrence & Formation

2-Hexenal naturally occurs in various fruits and vegetables, including apples, tomatoes, and green beans. It is formed through the enzymatic oxidation of linoleic acid, a process often triggered by plant tissue damage. This compound is significant in the context of "natural flavor" designations due to its presence in many edible plants and its role in the natural aroma profile of fresh produce.

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

4. Use in Flavors

2-Hexenal is utilized in flavor formulations to impart a fresh, green note, enhancing the authenticity of fruit and vegetable flavors. It is commonly used in apple, pear, and tomato flavor profiles. Typical use levels in finished food products range from 0.1 to 5 ppm, depending on the desired intensity and the complexity of the flavor system. It is relatively stable under acidic conditions but may degrade under high heat or prolonged storage, necessitating careful formulation considerations.

Citation hooks: FlavScents; FEMA GRAS documentation; formulation literature

5. Use in Fragrances

In the fragrance industry, 2-hexenal is valued for its ability to add a fresh, green top note to compositions. It is used in various fragrance families, including green, floral, and fruity scents. Concentration levels typically range from trace amounts to 0.5% in the final product, depending on the desired effect. Its volatility makes it a top note, contributing to the initial impression of a fragrance.

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. 05.062.
• United Kingdom: Follows EU regulations post-Brexit.
• Asia: Approved for use in Japan and China, with specific limits varying by country.
• Latin America: Generally accepted in Brazil and MERCOSUR countries, subject to local regulations.

Explicit approvals and harmonized assumptions are common, though specific limits may vary, necessitating verification for compliance in each region.

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 no specific ADI established but generally recognized as safe under FEMA GRAS. Dermal exposure in fragrances is limited by IFRA standards to prevent irritation and sensitization. Inhalation exposure is minimal due to its low volatility and typical use concentrations. Overall, the risk profile is similar across food and fragrance applications, with standard safety measures applicable.

Citation hooks: EFSA; FEMA; PubChem; toxicology literature

8. Practical Insights for Formulators

2-Hexenal is prized for its ability to impart a fresh, green note, enhancing the realism of fruit and vegetable flavors. It synergizes well with other aldehydes and esters, but formulators should be cautious of its reactivity, which can lead to off-notes if not stabilized properly. It is often under-used in complex formulations where its impact can be overshadowed by more dominant notes.

Citation hooks: FlavScents; industry practice

9. Confidence & Data Quality Notes

Data on 2-hexenal is well-established, with comprehensive sensory and regulatory information available. While specific numeric thresholds are not always documented, industry practices provide reliable guidance. Known data gaps include detailed toxicological studies, though existing data supports its safe use within established limits.

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 2026-08-11 12:39:10 GMT (p2)