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. 05.061
• Molecular Formula: C6H10O
• Molecular Weight: 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 fruits. The double bond in the (E)-configuration enhances its reactivity and sensory impact.

Citation hooks: FlavScents; PubChem; FEMA

2. Sensory Profile

(E)-2-hexenal is known for its strong, green, leafy odor reminiscent of freshly cut grass, green apples, and unripe fruits. 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 is relatively low, typically around 0.1 ppm, allowing it to be perceived even at minimal concentrations. In flavor applications, it serves as an impact note, adding freshness and realism to fruit and vegetable profiles.

Citation hooks: FlavScents; peer-reviewed sensory literature

3. Natural Occurrence & Formation

(E)-2-hexenal is naturally found in a variety of fruits and vegetables, including apples, tomatoes, and green leafy vegetables. It is formed through the enzymatic oxidation of linoleic acid, a process that occurs when plant tissues are damaged. This compound is significant in the designation of "natural flavor" due to its widespread occurrence in nature and its role in the aroma profiles of many fresh produce items.

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 used in fruit flavors, particularly apple, pear, and citrus, as well as in vegetable flavors like tomato and cucumber. Typical use levels in finished food or beverage products range from 0.1 to 5 ppm, with higher concentrations used in more robust flavor profiles. It is relatively stable under acidic conditions but can degrade under high heat or prolonged exposure to air, leading to potential off-flavors.

Citation hooks: FlavScents; FEMA GRAS documentation; formulation literature

5. Use in Fragrances

In fragrance applications, (E)-2-hexenal is used to add a fresh, green note to compositions. It is found in fragrance families such as green, floral, and fruity. Its role is often as a modifier or impact note, providing a natural, leafy character. Typical concentrations in fragrance formulations range from trace amounts to 0.5%, depending on the desired intensity. It is a top note due to its high volatility, 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. 05.061.
• United Kingdom: Aligns with EU regulations post-Brexit.
• Asia: Approved for use in Japan and China, with specific restrictions varying by country.
• Latin America: Generally accepted, but specific regulations may vary by country.

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, with an acceptable daily intake (ADI) not specifically established but implied through GRAS status. Dermal exposure in fragrance use is generally safe, though it may cause irritation or sensitization in sensitive individuals. IFRA provides guidelines to minimize these risks. Inhalation exposure is minimal due to its rapid evaporation and low use concentrations. Overall, the risk profiles are similar between food and fragrance applications, with no significant differences noted.

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 aldehydes and esters, enhancing fruity and floral notes. Formulators should be cautious of its reactivity, as it can lead to off-flavors if not properly stabilized. It is often under-used in complex formulations where its impact can be masked by other components.

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, though some variability exists in use levels and stability considerations. Known data gaps are minimal, primarily related to specific regional regulatory nuances.

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 2026-05-21 22:06:25 GMT (p2)