FlavScents AInsights Entry for Isobutyric Acid (CAS: 79-31-2)

1. Identity & Chemical Information

• Common Name(s): Isobutyric acid
• IUPAC Name: 2-Methylpropanoic acid
• CAS Number: 79-31-2
• FEMA Number: 2203
• Other Identifiers: FL No. 08.005, CoE No. 186
• Molecular Formula: C4H8O2
• Molecular Weight: 88.11 g/mol

Isobutyric acid is a carboxylic acid with a branched structure, characterized by a methyl group attached to the second carbon of the propanoic acid chain. This structural feature contributes to its distinct sour, cheesy odor, which is relevant in both flavor and fragrance applications.

Citation hooks: FlavScents; PubChem; FEMA

2. Sensory Profile

Isobutyric acid is known for its pungent, sour, and cheesy odor, often described as reminiscent of sweat or rancid butter. It has a strong, penetrating character with moderate diffusion. The taste threshold is relatively low, making it a potent impact note in flavor formulations. It is typically used to impart a tangy, fermented note in dairy and savory applications.

Citation hooks: FlavScents; peer-reviewed sensory literature

3. Natural Occurrence & Formation

Isobutyric acid occurs naturally in various foods, including cheese, yogurt, and other fermented products. It is formed through the fermentation process, where bacteria metabolize carbohydrates and proteins. This compound is also a byproduct of the Maillard reaction, contributing to the complex flavors in cooked foods. Its presence in natural sources allows it to be designated as a "natural flavor" in certain regulatory contexts.

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

4. Use in Flavors

Isobutyric acid is utilized in flavor formulations for its ability to enhance and modify dairy, savory, and fermented profiles. It is commonly used in cheese, butter, and yogurt flavors, as well as in savory snacks and sauces. Typical use levels in finished food products range from 0.5 to 5 ppm, with higher concentrations potentially leading to overpowering notes. It is stable under acidic conditions but may degrade under high heat or oxidative environments.

Citation hooks: FlavScents; FEMA GRAS documentation; formulation literature

5. Use in Fragrances

In fragrance applications, isobutyric acid is used to add a tangy, sour note that can enhance the realism of fruity and fermented accords. It is found in fragrance families such as gourmand and fougère. Typical concentrations in fragrance formulations are low, often below 0.1%, due to its potent odor. It contributes primarily to the top and middle notes due to its moderate volatility.

Citation hooks: FlavScents; IFRA; fragrance chemistry texts

6. Regulatory Status (Regional Overview)

• United States: Recognized as GRAS by FEMA for flavor use.
• European Union: Approved under Regulation (EC) No 1334/2008 with FL No. 08.005.
• United Kingdom: Aligns with EU regulations post-Brexit.
• Asia: Approved for use in Japan and China, with specific restrictions in certain ASEAN countries.
• Latin America: Generally accepted, with specific regulations in Brazil and MERCOSUR countries.

Explicit approvals and harmonized assumptions are common, though country-specific variability exists, particularly in Asia and Latin America.

Citation hooks: FEMA; EFSA; national authority publications

7. Toxicology, Safety & Exposure Considerations

• Oral Exposure: Isobutyric acid has a low acute toxicity profile, with an acceptable daily intake (ADI) not clearly established. Typical use levels in food are considered safe.
• Dermal Exposure: May cause irritation or sensitization in sensitive individuals. IFRA guidelines recommend caution in fragrance applications.
• Inhalation Exposure: Volatility may pose occupational exposure risks, necessitating adequate ventilation in manufacturing settings.

Risk profiles are generally consistent between food and fragrance applications, with dermal exposure requiring more careful management.

Citation hooks: EFSA; FEMA; PubChem; toxicology literature

8. Practical Insights for Formulators

Isobutyric acid is valued for its ability to impart a realistic tangy note in both flavors and fragrances. It synergizes well with other acids and esters to create complex profiles. Formulators should be cautious of its potent odor, which can easily dominate a blend if overused. It is often under-utilized in non-dairy applications, where it can add depth and authenticity.

Citation hooks: FlavScents; industry practice

9. Confidence & Data Quality Notes

Data on isobutyric acid is well-established, with comprehensive sensory and regulatory information available. Industry practices are documented, though some regional regulatory nuances may require further clarification. Known data gaps include specific ADI values and detailed dermal sensitization thresholds.

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 2026-02-13 08:38:32 GMT (p2)