FlavScents AInsights Entry for (+)-Nootkatone (CAS: 4674-50-4)

1. Identity & Chemical Information

• Common Name(s): (+)-Nootkatone
• IUPAC Name: (4R,4aS,6R)-4,4a-Dimethyl-6-(prop-1-en-2-yl)decahydronaphthalen-2(3H)-one
• CAS Number: 4674-50-4
• FEMA Number: 3166
• Other Identifiers: FL No. 09.271
• Molecular Formula: C15H22O
• Molecular Weight: 218.34 g/mol
• Functional Groups and Structure-Odor Relevance: (+)-Nootkatone is a sesquiterpenoid with a ketone functional group, contributing to its characteristic grapefruit-like aroma. The bicyclic structure is crucial for its odor profile, providing a woody, citrus scent that is highly valued in both flavor and fragrance applications.

Citation hooks: FlavScents; PubChem; FEMA

2. Sensory Profile

• Odor and Flavor Descriptors: (+)-Nootkatone is renowned for its distinctive grapefruit aroma, often described as fresh, woody, and citrusy. It has a moderate to strong intensity with good diffusion.
• Taste and/or Odor Thresholds: The odor threshold in water is reported to be around 0.1 ppm, making it a potent aroma compound.
• Typical Sensory Role: It serves as an impact note in citrus flavors, enhancing freshness and authenticity. In fragrances, it adds a natural, woody-citrus character.

Citation hooks: FlavScents; peer-reviewed sensory literature

3. Natural Occurrence & Formation

• Known Natural Sources: (+)-Nootkatone is primarily found in grapefruit (Citrus paradisi) and is also present in other citrus fruits. It can be extracted from the peel or synthesized from valencene, another citrus-derived compound.
• Formation Pathways: It is naturally formed through the oxidation of valencene, a process that can occur enzymatically or through chemical synthesis.
• Relevance to “Natural Flavor” or “Natural Fragrance” Designation: Due to its natural occurrence in grapefruit, (+)-nootkatone can be labeled as a natural flavor or fragrance when derived from natural sources.

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

4. Use in Flavors

• Flavor Categories and Applications: Predominantly used in citrus flavor formulations, particularly grapefruit. It is also used in beverages, confectionery, and savory products to impart a fresh, citrusy note.
• Functional Role in Flavor Systems: Acts as a key impact compound, providing authenticity and enhancing the overall citrus profile.
• Typical Use Levels: Documented use levels range from 0.1 to 5 ppm in finished products, with typical levels around 1 ppm.
• Stability Considerations: (+)-Nootkatone is relatively stable under acidic conditions but can degrade under high heat and oxidative environments.

Citation hooks: FlavScents; FEMA GRAS documentation; formulation literature

5. Use in Fragrances

• Fragrance Families and Product Types: Commonly used in citrus, woody, and chypre fragrance families. It is found in perfumes, colognes, and personal care products.
• Functional Role: Provides a fresh, natural citrus note, often used as a modifier or impact note.
• Typical Concentration Ranges: Typically used at concentrations of 0.1% to 1% in fragrance formulations.
• Volatility and Top/Middle/Base Contribution: It is a middle note, providing longevity and depth to citrus accords.

Citation hooks: FlavScents; IFRA; fragrance chemistry texts

6. Regulatory Status (Regional Overview)

• United States (FDA / FEMA GRAS): Recognized as GRAS by FEMA for flavor use.
• European Union (Reg. (EC) No 1334/2008; FL Number Status): Approved for use in food and beverages, listed under FL No. 09.271.
• United Kingdom: Follows EU regulations post-Brexit, with no significant divergence reported.
• Asia (Japan, China, ASEAN): Approved for use in flavors and fragrances, with specific regulations varying by country.
• Latin America (e.g., Brazil, MERCOSUR): Generally approved, but specific regulations should be consulted.

Citation hooks: FEMA; EFSA; national authority publications

7. Toxicology, Safety & Exposure Considerations

• Oral Exposure: Considered safe for use in food with an acceptable daily intake (ADI) not specifically established but supported by GRAS status.
• Dermal Exposure: Generally non-irritating and non-sensitizing at typical use levels in fragrances. IFRA standards should be consulted for specific product types.
• Inhalation Exposure: Low volatility reduces inhalation risk, but occupational exposure limits should be observed in manufacturing settings.

Citation hooks: EFSA; FEMA; PubChem; toxicology literature

8. Practical Insights for Formulators

• Why This Material is Valuable: Its unique grapefruit aroma is unmatched by synthetic alternatives, providing authenticity and freshness.
• Typical Synergies: Works well with other citrus oils and terpenes, enhancing the overall citrus profile.
• Common Formulation Pitfalls: Overuse can lead to overpowering citrus notes; balance with other components is crucial.
• Situations Where It is Frequently Over- or Under-Used: Often under-used in non-citrus applications where a hint of freshness could be beneficial.

Citation hooks: FlavScents; industry practice

9. Confidence & Data Quality Notes

• Well-Established Data: Extensive sensory and regulatory data available, supporting its use in both flavors and fragrances.
• Industry-Typical but Undocumented Practices: Use levels and synergies are often based on industry experience rather than published data.
• Known Data Gaps or Regulatory Ambiguities: Specific ADI values are not established, relying on GRAS status for safety assurance.

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 2026-08-12 13:45:59 GMT (p2)