# 3-mercaptohexyl Butyrate

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**Safety rating:** UNKNOWN
**CAS number:** 136954-21-7
**Category:** flavoring
**FDA GRAS:** no
**Adverse events (FDA AERS):** 0
**FDA recalls:** 0
**Last updated:** 2026-04-02

## Summary

3-mercaptohexyl Butyrate is a synthetic flavoring compound used to impart fruity and sulfurous notes in processed foods. It is not approved as a Generally Recognized As Safe (GRAS) substance by the FDA and has limited regulatory approval in most jurisdictions.

## 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 3-mercaptohexyl Butyrate?

3-mercaptohexyl Butyrate (CAS Number: 136954-21-7) is a synthetic organic compound classified as a flavoring agent. It belongs to the class of volatile flavor compounds known as thiols or mercaptan compounds, which contain sulfur functional groups. These compounds are responsible for distinctive aromas and tastes, often described as fruity, meaty, or savory. The butyrate ester structure combined with the hexyl-mercaptan moiety creates a specific flavor profile used in the food industry.

## Common Uses

When approved for use, 3-mercaptohexyl Butyrate is employed as a flavoring agent in various processed foods to enhance or create specific taste and aroma characteristics. Its applications are typically limited to products where fruity or complex sulfurous notes are desired. However, due to its non-GRAS status in the United States, its use is not generally permitted without specific regulatory approval for individual food applications.

In regions where it may be approved or listed as a flavor ingredient, it would typically be used in very small concentrations, measured in parts per million (ppm), as is standard practice with synthetic flavor compounds.

## Safety Assessment

According to FDA records, there have been zero adverse events reported in connection with 3-mercaptohexyl Butyrate, and no food recalls have been attributed to this substance. However, the absence of reported adverse events does not constitute formal safety approval or a GRAS determination.

The safety profile of flavor compounds is typically evaluated based on toxicological studies examining absorption, metabolism, and potential toxic effects at various dose levels. For 3-mercaptohexyl Butyrate, comprehensive safety data in the public domain is limited, which may contribute to its non-GRAS status.

Thiols and mercaptan compounds generally undergo hepatic metabolism in the body and are typically excreted relatively quickly. However, individual compounds within this chemical class can have different toxicological properties, necessitating case-by-case evaluation.

## Regulatory Status

3-mercaptohexyl Butyrate is not listed as a GRAS substance by the FDA, meaning it has not been formally recognized as safe for general use in food. This designation requires either a petition to the FDA demonstrating safety through scientific evidence or a qualified expert determination based on the substance's history of use.

In the European Union, flavor compounds are regulated under Commission Regulation (EC) No. 1334/2008, which requires flavoring substances to be evaluated for safety by the European Food Safety Authority (EFSA) before approval. The regulatory status of 3-mercaptohexyl Butyrate in the EU may differ from the United States.

Manufacturers wishing to use this substance would need to pursue either a Food Additive Petition (FAP) with the FDA or demonstrate compliance with applicable regulations in their specific jurisdiction.

## Key Studies

Limited published scientific literature specifically addresses 3-mercaptohexyl Butyrate in isolation. Research on structurally related thiol and ester compounds provides some context for understanding potential metabolic pathways and safety considerations, but direct toxicological studies on this particular compound are not readily available in public databases.

The flavor industry and regulatory agencies typically assess such compounds using standardized toxicological protocols including acute toxicity testing, repeated-dose studies, and genotoxicity assessments. The specific data from such studies for 3-mercaptohexyl Butyrate would be contained in proprietary dossiers submitted to regulatory agencies.

## 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. "3-mercaptohexyl Butyrate — Safety, regulation, and evidence." https://additivefacts.com/additives/3-mercaptohexyl-butyrate. Accessed 2026-05-19.