FlavScents AInsights Entry for Propionic Acid (CAS: 79-09-4)

1. Identity & Chemical Information

Propionic acid, also known as propanoic acid, is a naturally occurring carboxylic acid with the chemical formula C3H6O2 and a molecular weight of 74.08 g/mol. Its IUPAC name is propanoic acid. The CAS number for propionic acid is 79-09-4, and it is identified by FEMA number 2921. This compound is characterized by a carboxyl group (-COOH) which contributes to its acidic properties and its distinctive pungent odor. The structure-odor relevance is significant as the carboxyl group is responsible for the sour, vinegar-like smell that is typical of short-chain fatty acids.

Citation hooks: FlavScents; PubChem; FEMA

2. Sensory Profile

Propionic acid is known for its sharp, pungent odor reminiscent of vinegar, with a sour and slightly sweet undertone. It is often described as having a cheesy or fermented aroma, which can be quite intense and diffusive. The taste threshold for propionic acid is relatively low, making it a potent flavoring agent. In sensory applications, it serves as an impact note, providing a tangy, fermented character that can enhance the authenticity of dairy and fermented flavor profiles.

Citation hooks: FlavScents; peer-reviewed sensory literature

3. Natural Occurrence & Formation

Propionic acid occurs naturally in various foods, particularly in fermented products such as cheese and sourdough bread. It is produced by the fermentation of carbohydrates by propionibacteria. This compound is also a byproduct of the anaerobic digestion of organic matter. In the context of natural flavors, propionic acid is considered a natural component due to its presence in naturally fermented foods.

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

4. Use in Flavors

In the flavor industry, propionic acid is used to impart a tangy, fermented note to a variety of products, including baked goods, cheeses, and sauces. It is particularly valued in dairy and savory applications for its ability to enhance the perception of freshness and authenticity. Typical use levels in finished food products range from 10 to 100 ppm, with higher concentrations used in more robust flavor profiles. Propionic acid is stable under typical processing conditions but may degrade under extreme heat or alkaline conditions.

Citation hooks: FlavScents; FEMA GRAS documentation; formulation literature

5. Use in Fragrances

Propionic acid is less commonly used in fragrances due to its strong and pungent odor. However, it can be employed in trace amounts to add a realistic, fermented note to certain fragrance compositions, particularly those mimicking natural environments or food-related scents. Its volatility makes it a top note in fragrance formulations, contributing to the initial impact of the scent.

Citation hooks: FlavScents; IFRA; fragrance chemistry texts

6. Regulatory Status (Regional Overview)

In the United States, propionic acid is recognized as Generally Recognized As Safe (GRAS) by FEMA for use in food flavors. In the European Union, it is approved under Regulation (EC) No 1334/2008 and assigned the FL number 08.005. The United Kingdom follows similar regulations post-Brexit. In Asia, propionic acid is permitted in Japan and China, with specific use conditions. In Latin America, countries like Brazil and those in MERCOSUR also allow its use, though specific regulations may vary.

Citation hooks: FEMA; EFSA; national authority publications

7. Toxicology, Safety & Exposure Considerations

Propionic acid is considered safe for use in food and fragrances when used within recommended limits. For oral exposure, it has a high margin of safety with an Acceptable Daily Intake (ADI) established by regulatory bodies. Dermal exposure in fragrance applications is generally low risk, but it can cause irritation in high concentrations. Inhalation exposure is minimal due to its low volatility in typical use concentrations. Overall, the risk profiles for food and fragrance applications are similar, with safety ensured through adherence to regulatory guidelines.

Citation hooks: EFSA; FEMA; PubChem; toxicology literature

8. Practical Insights for Formulators

Propionic acid is valued for its ability to impart a tangy, fermented note that enhances the authenticity of dairy and savory flavors. It synergizes well with other acids and fermented notes, but care must be taken to avoid overuse, which can lead to an overpowering and unpleasant aroma. Formulators should consider its volatility and potential for irritation when used in fragrance applications.

Citation hooks: FlavScents; industry practice

9. Confidence & Data Quality Notes

The data on propionic acid is well-established, with comprehensive documentation available from authoritative sources. Industry practices are well-documented, though some variability exists in regional regulatory interpretations. Known data gaps are minimal, with most information being consistent across sources.

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

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 2026-03-31 12:36:05 GMT (p2)