FlavScents AInsights Entry for (E)-2-hexenal (CAS: 6728-26-3)

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 No. 05.062
• Molecular Formula: C6H10O
• Molecular Weight: 98.15 g/mol

(E)-2-hexenal is an α,β-unsaturated aldehyde characterized by its functional groups, which include an aldehyde group and a double bond in the E-configuration. This structure contributes to its distinctive green, leafy odor, often associated with freshly cut grass or unripe fruit. The presence of the aldehyde group is crucial for its reactivity and sensory properties, making it a valuable component in flavor and fragrance formulations.

Citation hooks: FlavScents; PubChem; FEMA

2. Sensory Profile

(E)-2-hexenal is renowned for its potent green, leafy odor, reminiscent of freshly cut grass, green apples, and unripe fruit. It is often described as having a high intensity and sharp diffusion, making it an impactful top note in both flavors and fragrances. The odor threshold is relatively low, allowing it to be perceived at minimal concentrations, although specific threshold values are not consistently reported in the literature. Its sensory role is typically as an impact note, providing freshness and a natural green character to formulations.

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 a key component in the natural flavor profile 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

In flavor applications, (E)-2-hexenal is used to impart a fresh, green note to a variety of products, including beverages, confectionery, and savory items. It is particularly valued in apple, pear, and tomato flavors. Typical use levels in finished 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 can be prone to oxidation, which may alter its sensory characteristics.

Citation hooks: FlavScents; FEMA GRAS documentation; formulation literature

5. Use in Fragrances

(E)-2-hexenal is utilized in fragrance formulations to provide a fresh, green top note. It is commonly found in floral, fruity, and green fragrance families and is used in products such as perfumes, air fresheners, and personal care items. Concentration levels typically range from trace amounts to 0.5%, depending on the formulation and desired effect. Its volatility makes it a prominent top note, contributing to the initial impression of the fragrance.

Citation hooks: FlavScents; IFRA; fragrance chemistry texts

6. Regulatory Status (Regional Overview)

In the United States, (E)-2-hexenal is recognized as GRAS (Generally Recognized As Safe) by FEMA for flavor use. In the European Union, it is listed under Regulation (EC) No 1334/2008 with FL No. 05.062. The UK follows similar regulations post-Brexit. In Asia, including Japan and China, it is generally accepted for use in flavors and fragrances, although specific regulations may vary. In Latin America, countries like Brazil and those in MERCOSUR typically align with international standards, but local regulations should be consulted for specific guidance.

Citation hooks: FEMA; EFSA; national authority publications

7. Toxicology, Safety & Exposure Considerations

For oral exposure, (E)-2-hexenal is considered safe at typical use levels in food, with no specific ADI established. The compound's low volatility and reactivity reduce the risk of significant inhalation exposure in occupational settings. Dermal exposure in fragrance applications is generally safe, but it may cause irritation or sensitization in sensitive individuals. IFRA guidelines should be consulted for specific use restrictions in fragrances. Overall, the risk profiles for food and fragrance applications are similar, with low exposure levels posing minimal risk.

Citation hooks: EFSA; FEMA; PubChem; toxicology literature

8. Practical Insights for Formulators

(E)-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 the formulation. Common pitfalls include overuse, which can lead to an overpowering or harsh aroma. It is often under-utilized in complex formulations where its impact can be masked by heavier notes. Formulators should consider its volatility and potential for oxidation when designing products.

Citation hooks: FlavScents; industry practice

9. Confidence & Data Quality Notes

The data on (E)-2-hexenal is well-established, with comprehensive sensory and regulatory information available. Industry practices are well-documented, although specific sensory thresholds and regional regulatory nuances may require further verification. Known data gaps include precise odor threshold values and detailed toxicological studies, which are often generalized from similar compounds.

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 2026-03-21 07:56:52 GMT (p2)