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. 05.073
• Molecular Formula: C6H10O
• Molecular Weight: 98.15 g/mol
• Functional Groups and Structure–Odor Relevance: (E)-2-hexenal is an α,β-unsaturated aldehyde, which contributes to its characteristic green, leafy odor. The presence of the double bond in the (E) configuration is crucial for its sensory properties, providing a sharp, fresh note often associated with freshly cut grass or green leaves.

Citation hooks: FlavScents; PubChem; FEMA

2. Sensory Profile

• Odor and Flavor Descriptors: (E)-2-hexenal is known for its intense green, leafy, and slightly fruity odor. It is often described as having a fresh, grassy scent with nuances of apple and tomato leaf.
• Taste and/or Odor Thresholds: The odor threshold is relatively low, making it a potent impact compound in flavor and fragrance formulations.
• Typical Sensory Role: It serves as an impact note, providing freshness and realism to green and fruity accords. It is often used to enhance the perception of freshness in both flavors and fragrances.

Citation hooks: FlavScents; peer-reviewed sensory literature

3. Natural Occurrence & Formation

• Known Natural Sources: (E)-2-hexenal is naturally found in a variety of fruits and vegetables, including apples, tomatoes, and green leafy vegetables. It is also present in essential oils such as peppermint and spearmint.
• Formation Pathways: It is typically formed through the enzymatic degradation of fatty acids, particularly linolenic acid, via the lipoxygenase pathway. This process is common in plant tissues when they are damaged or crushed.
• Relevance to “Natural Flavor” or “Natural Fragrance” Designation: Due to its natural occurrence in many plants, (E)-2-hexenal can be labeled as a natural flavor or fragrance component when derived from natural sources.

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

4. Use in Flavors

• Flavor Categories and Applications: (E)-2-hexenal is widely used in fruit, vegetable, and herbal flavor profiles. It is particularly prominent in apple, pear, and tomato flavors.
• Functional Role in Flavor Systems: It acts as a key impact compound, providing freshness and authenticity to green and fruity flavors.
• Typical Use Levels: Documented use levels range from 0.1 to 5 ppm in finished food products, with typical levels around 1 ppm. These values are industry-typical and may vary based on the specific application.
• Stability Considerations: (E)-2-hexenal is relatively stable under acidic conditions but can be prone to oxidation. It is sensitive to heat, which may lead to degradation or loss of its characteristic odor.

Citation hooks: FlavScents; FEMA GRAS documentation; formulation literature

5. Use in Fragrances

• Fragrance Families and Product Types: It is commonly used in green, fruity, and floral fragrance compositions. It is found in personal care products, household cleaners, and air fresheners.
• Functional Role: (E)-2-hexenal serves as a modifier and impact note, enhancing the freshness and realism of fragrance compositions.
• Typical Concentration Ranges: It is typically used at concentrations ranging from 0.01% to 0.1% in fragrance formulations.
• Volatility and Top/Middle/Base Contribution: Due to its high volatility, (E)-2-hexenal is primarily a top note, providing an initial burst of freshness.

Citation hooks: FlavScents; IFRA; fragrance chemistry texts

6. Regulatory Status (Regional Overview)

• United States (FDA / FEMA GRAS): Recognized as GRAS (Generally Recognized As Safe) for use in food flavors.
• European Union (Reg. (EC) No 1334/2008; FL Number Status): Approved for use as a flavoring substance under the EU flavoring regulation.
• United Kingdom (Post-Brexit Alignment or Divergence): Follows EU regulations; no significant divergence reported.
• Asia (Japan, China, ASEAN): Generally permitted for use in flavors, subject to specific regional regulations.
• Latin America (e.g., Brazil, MERCOSUR): Permitted for use in flavors, with specific regulations varying by country.

Citation hooks: FEMA; EFSA; national authority publications

7. Toxicology, Safety & Exposure Considerations

• Oral Exposure: (E)-2-hexenal has a low acute toxicity profile when used at typical flavor concentrations. The ADI (Acceptable Daily Intake) is not specifically established, but it is considered safe under current usage levels.
• Dermal Exposure: In fragrance applications, it may cause irritation or sensitization in sensitive individuals. IFRA guidelines provide usage limits to mitigate these risks.
• Inhalation Exposure: As a volatile compound, inhalation exposure is possible, but it is generally considered safe at typical fragrance concentrations. Occupational exposure limits are not specifically established but should be managed through standard industrial hygiene practices.

Citation hooks: EFSA; FEMA; PubChem; toxicology literature

8. Practical Insights for Formulators

• Why This Material is Valuable: (E)-2-hexenal is prized for its ability to impart a fresh, green character to both flavors and fragrances, enhancing the perception of naturalness and freshness.
• Typical Synergies: It blends well with other green notes, citrus, and fruity compounds, enhancing the overall freshness and complexity of formulations.
• Common Formulation Pitfalls: Overuse can lead to an overly sharp or harsh profile. It is important to balance its intensity with other components.
• Situations Where It is Frequently Over- or Under-used: It is often under-used in formulations seeking a natural green note due to its potency and potential for overpowering other elements.

Citation hooks: FlavScents; industry practice

9. Confidence & Data Quality Notes

• Well-Established Data: The sensory profile and natural occurrence of (E)-2-hexenal are well-documented in both scientific literature and industry practice.
• Industry-Typical but Undocumented Practices: Usage levels and formulation strategies are often based on industry experience rather than formal studies.
• Known Data Gaps or Regulatory Ambiguities: Specific ADI values are not established, and regional regulatory nuances may exist.

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 2026-09-12 05:52:25 GMT (p2)