# 2-trans-6-cis-nonadienal

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**Safety rating:** UNKNOWN
**CAS number:** 557-48-2
**Category:** flavoring
**FDA GRAS:** no
**Adverse events (FDA AERS):** 0
**FDA recalls:** 0
**Last updated:** 2026-04-04

## Summary

2-trans-6-cis-nonadienal is a naturally occurring organic compound used as a flavoring agent in food products. It contributes aldehyde and fatty acid-derived flavor notes commonly found in nuts, dairy, and cooked foods.

## Regulatory status

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

## Detailed analysis

## What is 2-trans-6-cis-nonadienal?

2-trans-6-cis-nonadienal (CAS Number 557-48-2) is an unsaturated aldehyde compound classified as a flavoring agent. It exists naturally in various foods including nuts, vegetable oils, and dairy products, where it develops during cooking, fermentation, or oxidation processes. The compound is a nine-carbon chain with two double bonds in specific geometric configurations, which determine its sensory properties and chemical reactivity.

As an additive, 2-trans-6-cis-nonadienal is synthesized for use in flavor formulations targeting processed foods, beverages, and other consumer products. It belongs to the broader category of aldehyde-based flavorings, which are commonly used across the food industry.

## Common Uses

This flavoring agent is primarily used in:
- Processed snack foods and savory products
- Beverage flavorings
- Dairy product flavoring systems
- Baked goods and cereal products
- Condiments and sauces
- Plant-based and meat analog products

The compound contributes nutty, fatty, and oxidized flavor notes that enhance the sensory profile of finished products. Its use concentrations in food are typically very small, measured in parts per million (ppm).

## Safety Assessment

The FDA has not granted 2-trans-6-cis-nonadienal GRAS (Generally Recognized As Safe) status, meaning it does not have formal approval through either the GRAS notification process or food additive petition route. However, the absence of GRAS status does not indicate the substance is unsafe—rather, it reflects that formal regulatory approval documentation has not been completed in the United States.

According to FDA records, there have been zero adverse events reported and zero product recalls associated with this additive, suggesting no significant safety incidents in consumer use.

The compound's safety profile is partially informed by its natural occurrence in foods and chemical similarity to other approved aldehydes. However, the lack of published peer-reviewed studies specific to this compound means comprehensive toxicological data are limited in the public domain. Most aldehydes used as flavorings undergo safety evaluation based on general aldehyde toxicology and structure-activity relationships.

## Regulatory Status

In the United States, while not GRAS-designated, 2-trans-6-cis-nonadienal may be used in food if it complies with applicable regulations or if a food additive petition has been filed and deemed acceptable by the FDA. Its regulatory status varies internationally:

- **European Union**: The compound does not appear on the EU's official list of approved flavoring agents (EC Regulation 1334/2008), restricting its use in EU food products.
- **Other regions**: Regulatory status varies; some countries may permit it under general flavoring provisions while others may have specific restrictions.

The distinction between GRAS and non-GRAS status reflects the complexity of the U.S. food additive regulatory framework rather than a definitive safety conclusion.

## Key Studies

Published scientific literature on 2-trans-6-cis-nonadienal is limited. The compound has been identified in:n- Natural food volatiles research, particularly in studies analyzing lipid oxidation byproducts
- Flavor chemistry investigations of nut and dairy products
- Studies on volatile organic compounds in processed foods

Because this is a specialty flavoring with limited commercial application, comprehensive toxicological studies may not be publicly available. Safety assessments would typically rely on:
- General aldehyde toxicology data
- Structural similarity to approved flavoring agents
- Levels of use (typically very low concentrations)
- Historical food use patterns

Further research and formal safety evaluation data would strengthen the evidence base for this additive.

## 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. "2-trans-6-cis-nonadienal — Safety, regulation, and evidence." https://additivefacts.com/additives/2-trans-6-cis-nonadienal. Accessed 2026-05-20.