# Trans-4-hexenal

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> Markdown URL: https://additivefacts.com/additives/trans-4-hexenal.md

**Safety rating:** SAFE
**CAS number:** 25166-87-4
**Category:** flavoring
**FDA GRAS:** no
**Adverse events (FDA AERS):** 0
**FDA recalls:** 0
**Last updated:** 2026-04-02

## Summary

Trans-4-hexenal is a volatile organic compound used as a flavoring agent in food products. It provides herbaceous and green fruit flavor notes and is employed in small quantities to enhance the sensory profile of various food and beverage applications.

## Regulatory status

| Country | Status |
| --- | --- |
| United States | approved |
| European Union | not_evaluated |
| United Kingdom | not_evaluated |
| Canada | not_evaluated |
| Australia | not_evaluated |
| Japan | not_evaluated |
| South Korea | not_evaluated |
| Brazil | not_evaluated |
| China | not_evaluated |
| India | not_evaluated |

## Detailed analysis

## What is Trans-4-hexenal?

Trans-4-hexenal (CAS Number: 25166-87-4) is a six-carbon aldehyde classified as a flavoring agent. It exists as a colorless to pale yellow liquid with a characteristic green, herbaceous odor reminiscent of freshly cut grass and unripe fruit. The compound is one of numerous volatile organic compounds naturally occurring in plants and is also produced synthetically for use in the flavor industry.

## Common Uses

Trans-4-hexenal is utilized primarily as a flavoring agent in the food and beverage industry. Its green and herbaceous sensory properties make it particularly valuable in:

- Fruit beverages and juices (apple, pear, and melon flavors)
- Dairy products including yogurts and flavored milk
- Baked goods and grain-based products
- Confectionery and hard candies
- Non-alcoholic beverages
- Savory snack foods

The compound is used at very low concentrations, typically measured in parts per million (ppm), to achieve desired flavor profiles without sensory dominance. Its volatile nature means it contributes primarily to the aroma rather than taste perception.

## Safety Assessment

Trans-4-hexenal has not been formally listed as Generally Recognized As Safe (GRAS) by the FDA under its own designation. However, it exists within a complex regulatory landscape for flavoring compounds. The FDA maintains that certain flavoring substances may be used safely based on industry standards and historical use patterns, even without explicit GRAS status.

According to available FDA records, there are zero reported adverse events associated with trans-4-hexenal and zero product recalls attributed to this ingredient. This absence of reported safety incidents, combined with its extremely limited use levels in food products, suggests a favorable safety profile in practical applications.

The compound is structurally similar to other short-chain aldehydes found naturally in foods and used as flavoring agents. Its chemical class and volatility characteristics suggest rapid metabolism and elimination from the body when ingested in food-relevant quantities.

## Regulatory Status

The regulatory status of trans-4-hexenal varies by jurisdiction:

**United States:** While not formally GRAS-listed, trans-4-hexenal may be used as a flavoring ingredient subject to FDA regulations (21 CFR Part 182 and related sections). The flavor industry operates under an informal regulatory framework where many traditionally-used compounds are permitted based on the Flavor and Extract Manufacturers' Association (FEMA) GRAS program, which independently evaluates flavor safety.

**European Union:** Trans-4-hexenal is listed in the EU's Flavouring Regulation (EC 1334/2008) as a permitted flavoring substance, subject to specified purity criteria and use level restrictions.

**Other Markets:** Approval and use permissions vary in other countries, with some markets following EFSA or other regional guidance.

## Key Studies

Limited published research specifically addresses trans-4-hexenal toxicology. However, relevant data includes:

- Studies on structurally similar C6 aldehydes (hexanal, trans-2-hexenal) showing low acute toxicity and minimal chronic effects at food-relevant exposure levels
- Natural occurrence studies documenting trans-4-hexenal in foods including fresh produce, indicating historical human dietary exposure
- Metabolic studies on related aldehydes demonstrating rapid oxidation to carboxylic acids and glucuronidation, supporting efficient elimination
- FEMA evaluations of related short-chain aldehydes as flavoring agents

The absence of specific toxicological data on trans-4-hexenal reflects its minimal regulatory profile rather than identified safety concerns. Its classification as a flavoring compound used at trace levels suggests low risk assessment priority compared to food components used in larger quantities.

## Sources

- FDA Substances Added to Food (CFSAN)
- OpenFDA Adverse Event Reporting System (AERS)
- OpenFDA Food Recalls
- EFSA OpenFoodTox
- EU Food Additive Portal

## Citation

Additive Facts. "Trans-4-hexenal — Safety, regulation, and evidence." https://additivefacts.com/additives/trans-4-hexenal. Accessed 2026-05-19.