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

1. Identity & Chemical Information

• Common Name(s): Propionic acid
• IUPAC Name: Propanoic acid
• CAS Number: 79-09-4
• FEMA Number: 2924
• Other Identifiers: FL No. 08.002
• Molecular Formula: C₃H₆O₂
• Molecular Weight: 74.08 g/mol

Propionic acid is a carboxylic acid with a three-carbon chain and a carboxyl group (COOH) at one end. Its structure contributes to its characteristic pungent odor, which is often described as similar to body odor or sour milk. The presence of the carboxyl group is crucial for its acidic properties and its role in flavor and fragrance applications.

Citation hooks: FlavScents; PubChem; FEMA

2. Sensory Profile

Propionic acid is known for its sharp, pungent odor reminiscent of vinegar and sour milk. It has a strong, penetrating aroma with moderate diffusion. In terms of taste, it is sour and slightly acrid, contributing to its use as a flavoring agent in various food products. The odor threshold for propionic acid is relatively low, making it a potent impact note in formulations.

Typically, propionic acid is used to impart a tangy, fermented note in flavor systems, often enhancing the authenticity of dairy and fermented products. It can also serve as a background modifier, adding complexity to savory profiles.

Citation hooks: FlavScents; peer-reviewed sensory literature

3. Natural Occurrence & Formation

Propionic acid occurs naturally in various foods, particularly those undergoing fermentation processes. It is found in Swiss cheese, where it is produced by Propionibacterium during fermentation. Additionally, it can be formed through the breakdown of fatty acids and carbohydrates in anaerobic conditions.

In the context of "natural flavor" designation, propionic acid can be considered natural if derived from fermentation or other natural processes. Its presence in fermented foods underscores its relevance in natural flavor formulations.

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

4. Use in Flavors

Propionic acid is widely used in flavor applications, particularly in dairy, bakery, and savory products. It acts as a flavor enhancer and preservative, contributing to the tangy, fermented notes in cheese and bread. Typical use levels in food range from 100 to 500 ppm, with higher concentrations used in specific applications like cheese flavoring.

Stability-wise, propionic acid is relatively stable under acidic conditions but may degrade at high temperatures or in alkaline environments. Formulators should consider its volatility and potential for off-notes when used in high concentrations.

Citation hooks: FlavScents; FEMA GRAS documentation; formulation literature

5. Use in Fragrances

In fragrance applications, propionic acid is less commonly used due to its strong odor. However, it can be employed in trace amounts to add realism to certain fragrance profiles, particularly those mimicking natural fermentation or dairy notes. It is typically used in low concentrations, often below 0.1%, to avoid overpowering the fragrance composition.

Propionic acid contributes primarily to the top notes due to its high volatility, providing an initial sharpness that can enhance the freshness 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. No specific restrictions for fragrance use.
• European Union: Approved under Regulation (EC) No 1334/2008 with FL No. 08.002.
• United Kingdom: Follows EU regulations post-Brexit with no significant divergence reported.
• Asia: Approved for use in Japan and China, with specific limits varying by country.
• Latin America: Generally accepted in MERCOSUR countries, with Brazil having specific guidelines for use in food.

Propionic acid is widely accepted for use in both flavors and fragrances, with harmonized regulations across major regions. However, formulators should verify specific country regulations to ensure compliance.

Citation hooks: FEMA; EFSA; national authority publications

7. Toxicology, Safety & Exposure Considerations

Propionic acid is considered safe for use in food and fragrance applications when used within recommended limits. For oral exposure, it has a high margin of safety, with an ADI established by JECFA. Dermal exposure in fragrance use is generally low risk, but it can cause irritation in high concentrations. IFRA guidelines should be consulted for specific use limits in fragrances.

Inhalation exposure is typically minimal due to its low volatility in finished products, but occupational exposure should be managed with appropriate ventilation and protective equipment.

Citation hooks: EFSA; FEMA; PubChem; toxicology literature

8. Practical Insights for Formulators

Propionic acid is valued for its ability to impart tangy, fermented notes in flavor systems, enhancing the authenticity of dairy and bakery products. It synergizes well with other acids and savory compounds, but care must be taken to avoid overuse, which can lead to off-notes.

Common pitfalls include its volatility and potential for overpowering other flavor components. Formulators should balance its use with complementary ingredients to achieve the desired sensory profile.

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 generally consistent, though specific use levels may vary by application. Known data gaps are minimal, but ongoing research may refine understanding of its sensory and safety profiles.

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 2026-07-13 21:57:43 GMT (p2)