1. Identity & Chemical Information

• Common name(s): (E)-2-hexenal, Leaf aldehyde
• IUPAC name: (E)-hex-2-enal
• CAS number: 6728-26-3
• FEMA number: 3429
• Other identifiers: FL number 02.015, CoE number 205
• Molecular formula and molecular weight: C6H10O; 98.15 g/mol
• Functional groups and structure–odor relevance: (E)-2-hexenal is an α,β-unsaturated aldehyde. The presence of the aldehyde group contributes to its characteristic green, leafy odor, which is often associated with freshly cut grass or unripe fruit. The double bond in the (E)-configuration enhances its volatility and diffusion, making it a potent odorant.

Citation hooks: FlavScents; PubChem; FEMA

2. Sensory Profile

(E)-2-hexenal is characterized by its strong, green, leafy odor reminiscent of freshly cut grass or green apples. It is often described as having a sharp, penetrating aroma with moderate to high intensity. The compound is used as an impact note in flavor and fragrance formulations, providing a fresh, natural green character. The odor threshold for (E)-2-hexenal is relatively low, making it effective even at minimal concentrations.

Citation hooks: FlavScents; peer-reviewed sensory literature

3. Natural Occurrence & Formation

(E)-2-hexenal is naturally found in a variety of plants and fruits, including apples, tomatoes, and green tea. It is formed through the enzymatic degradation of fatty acids, specifically linolenic acid, via the lipoxygenase pathway. This compound is often associated with the "green" aroma of freshly cut plants and is considered a key component in the natural flavor and fragrance profiles of many fruits and vegetables. Its presence in natural sources supports its designation as a "natural flavor" or "natural fragrance" component.

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

4. Use in Flavors

(E)-2-hexenal is widely used in flavor formulations to impart a fresh, green note. It is commonly employed in fruit flavors, such as apple, pear, and melon, as well as in vegetable flavors like tomato and cucumber. Its functional role in flavor systems is as an impact note, providing authenticity and enhancing the overall freshness of the flavor profile. Typical use levels in finished food or beverage products range from 0.1 to 5 ppm, depending on the desired intensity and the specific application. (E)-2-hexenal 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, (E)-2-hexenal is valued for its ability to impart a fresh, green, and natural character. It is used in a variety of fragrance families, including floral, fruity, and green compositions. Its functional role is often as a modifier or impact note, enhancing the realism and freshness of the fragrance. Typical concentration ranges in fragrance formulations are from trace amounts up to 0.5%, depending on the desired effect. Due to its high volatility, (E)-2-hexenal is primarily 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: (E)-2-hexenal is approved for use as a flavoring agent under FEMA GRAS status. It is also recognized by the FDA as a safe substance when used in accordance with good manufacturing practices.
• European Union: Listed under Regulation (EC) No 1334/2008 with FL number 02.015, (E)-2-hexenal is approved for use as a flavoring substance.
• United Kingdom: Post-Brexit, the regulatory status aligns with the EU, maintaining approval for use as a flavoring substance.
• Asia: In Japan, (E)-2-hexenal is permitted for use in food flavors. Regulatory information for China and ASEAN countries is less specific but generally aligns with international standards.
• Latin America: In Brazil and other MERCOSUR countries, (E)-2-hexenal is approved for use in food flavors, following international guidelines.

Citation hooks: FEMA; EFSA; national authority publications

7. Toxicology, Safety & Exposure Considerations

For oral exposure, (E)-2-hexenal is considered safe when used within the limits established by FEMA and other regulatory bodies. The compound has a low acute toxicity profile, and no adverse effects are expected at typical use levels in food. Dermal exposure in fragrance applications is generally safe, but (E)-2-hexenal can cause irritation or sensitization in sensitive individuals. IFRA provides guidelines to minimize such risks. Inhalation exposure is primarily relevant in occupational settings, where adequate ventilation and protective measures are recommended to prevent irritation due to its volatility.

Citation hooks: EFSA; FEMA; PubChem; toxicology literature

8. Practical Insights for Formulators

(E)-2-hexenal is a valuable material 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 and authenticity of formulations. Common pitfalls include overuse, which can lead to an overly sharp or harsh aroma, and oxidation, which can alter its sensory properties. Formulators should consider its volatility and potential for oxidation when designing products, ensuring proper storage and handling to maintain quality.

Citation hooks: FlavScents; industry practice

9. Confidence & Data Quality Notes

The data on (E)-2-hexenal is well-established, with comprehensive information available from authoritative sources such as FEMA and EFSA. Industry practices are well-documented, though some regional regulatory nuances may exist. Known data gaps are minimal, and the compound's safety profile is supported by extensive research.

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 2026-01-22 22:08:26 GMT (p2)