FlavScents AInsights Entry for (S)-2-methyl butyric acid (CAS: 1730-91-2)

1. Identity & Chemical Information

• Common Name(s): (S)-2-methyl butyric acid, (S)-2-methylbutanoic acid
• IUPAC Name: (S)-2-methylbutanoic acid
• CAS Number: 1730-91-2
• FEMA Number: 2703
• Other Identifiers: FL No. 08.005
• Molecular Formula: C5H10O2
• Molecular Weight: 102.13 g/mol
• Functional Groups and Structure–Odor Relevance: (S)-2-methyl butyric acid is a carboxylic acid with a branched alkyl chain. The presence of the carboxyl group contributes to its acidic properties, while the methyl branching influences its odor profile, imparting a cheesy, sweaty, and slightly fruity aroma.

Citation hooks: FlavScents; PubChem; FEMA

2. Sensory Profile

(S)-2-methyl butyric acid is characterized by its strong, penetrating odor reminiscent of cheese, sweat, and fermented fruits. It is often described as having a sour, rancid, and slightly fruity note. The intensity of its odor is high, making it a potent impact note in formulations. The taste threshold is relatively low, contributing to its effectiveness in small quantities. It is typically used as a background realism enhancer or as a modifier to add depth and authenticity to flavor profiles.

Citation hooks: FlavScents; peer-reviewed sensory literature

3. Natural Occurrence & Formation

(S)-2-methyl butyric acid occurs naturally in various foods, including cheese, beer, and certain fruits. It is formed through the fermentation process, where microbial activity converts carbohydrates into this compound. It is also a byproduct of the Maillard reaction, contributing to the complex flavors in cooked foods. Its presence in natural sources qualifies it for use in "natural flavor" designations under certain regulatory frameworks.

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

4. Use in Flavors

(S)-2-methyl butyric acid is widely used in flavor formulations, particularly in dairy, fruit, and savory applications. It serves as a key component in cheese and butter flavors, enhancing the authenticity and richness of these profiles. Typical use levels in finished food products range from 0.1 to 5 ppm, depending on the desired intensity and application. It is stable under typical processing conditions but may degrade under extreme heat or acidic environments.

Citation hooks: FlavScents; FEMA GRAS documentation; formulation literature

5. Use in Fragrances

In fragrance applications, (S)-2-methyl butyric acid is used to impart a naturalistic, animalic note, often in trace amounts to enhance realism. It is found in fragrance families such as chypre and fougère, where it acts as a modifier or impact note. Typical concentration ranges are from 0.01% to 0.1% in the final product. Its volatility allows it to contribute to the top and middle notes of a fragrance composition.

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 ASEAN countries.
• Latin America: Generally accepted in Brazil and MERCOSUR countries, with some regional variations.

Explicit approvals exist in major markets, but formulators should verify specific country regulations due to potential variability.

Citation hooks: FEMA; EFSA; national authority publications

7. Toxicology, Safety & Exposure Considerations

For oral exposure, (S)-2-methyl butyric acid is considered safe at typical use levels, with an acceptable daily intake (ADI) established by regulatory bodies. Dermal exposure in fragrance applications is generally safe, though it may cause irritation or sensitization in sensitive individuals. Inhalation exposure is minimal due to its low volatility, but occupational safety measures should be observed in manufacturing settings. The risk profiles for food and fragrance applications are similar, with no significant differences noted.

Citation hooks: EFSA; FEMA; PubChem; toxicology literature

8. Practical Insights for Formulators

(S)-2-methyl butyric acid is valued for its ability to impart authenticity and complexity to both flavors and fragrances. It synergizes well with other fatty acids and esters, enhancing creamy and fruity notes. Formulators should be cautious of its potent odor, which can easily overpower a composition if overused. It is often underutilized in savory applications, where it can add depth and umami character.

Citation hooks: FlavScents; industry practice

9. Confidence & Data Quality Notes

The data on (S)-2-methyl butyric acid is well-established, with comprehensive sensory and regulatory information available. Industry practices are well-documented, though some regional regulatory nuances may require further verification. Known data gaps are minimal, primarily related to specific regional regulatory updates.

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 2026-07-02 05:44:53 GMT (p2)