Kojic Acid (CAS 501-30-4) — Citrus Top Note Fragrance Ingredient
Kojic Acid
CAS 501-30-4
What Is Kojic Acid?
Kojic acid is a natural compound produced by fungi during fermentation, commonly found in skincare products for its skin-brightening properties. It’s derived from fermented rice, soy, and malt. This ingredient matters because it’s a gentle alternative to harsh skin-lightening agents, helping reduce hyperpigmentation without irritating sensitive skin.
Safety Profile
USE WITH AWARENESSWhat Does Kojic Acid Smell Like?
Kojic acid is nearly odorless with only faint fungal/musty undertones detectable at high concentrations. Its neutral olfactory profile makes it ideal for fragrance-free skincare formulations where scent interference must be avoided. The molecule lacks volatile top notes and doesn’t contribute to dry-down characteristics, functioning purely as an active ingredient rather than a perfumery material.
Scent Profile
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
2D Molecular Structure
SMILES: OCC1=CC(=O)C(O)=CO1
Chemistry, Properties & Perfumer Guide
The Chemistry
Kojic acid is a γ-pyrone derivative (5-hydroxy-2-(hydroxymethyl)-4H-pyran-4-one) produced by Aspergillus and Penicillium fungi species during aerobic fermentation. This heterocyclic compound features both hydroxyl and carbonyl functional groups that enable its chelating properties. Industrially produced through fungal fermentation of starches, its planar structure allows for effective tyrosinase inhibition through copper chelation at the enzyme’s active site.
Physical & Chemical Properties
| Melting Point | 153.5 °C |
|---|---|
| Molecular Weight | 142.11 g/mol |
| XLogP | -0.9 |
| Solubility | Soluble in polar organic solvents |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Skincare | 1-2% | Up to 4% | Depigmenting agent |
| Cosmetics | 0.5-1% | Up to 2% | Antioxidant properties |
Classic Accords
Tip: Use kojic acid in water-based phases with pH below 7.0 for optimal stability.
Alternatives & Comparisons
Gentler skin-brightener derived from bearberry, preferred for sensitive skin formulations.
Synthetic alternative with stronger melanin-inhibition effects but higher irritation potential.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. IFRA, REACH, EU Cosmetics Regulation standards update periodically. Consult current IFRA Standards Library before formulating. Not legal or regulatory advice.
IFRA Status
Not restricted by IFRA – primarily used as cosmetic active rather than fragrance ingredient.
GHS Classification
RIFM Assessment
RIFM has not evaluated kojic acid as it’s primarily classified as a cosmetic active ingredient.
Sustainability
Kojic acid production through fungal fermentation is relatively sustainable, utilizing agricultural byproducts as substrates. However, synthetic production methods are being developed to reduce batch variability and improve yield efficiency. The compound is biodegradable and doesn’t bioaccumulate.
Explore Kojic Acid
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References
- PubChem Compound Summary for CID 3840 (Kojic acid) PubChem 3840
- Bentley R. (2006). From miso, saké and shoyu to cosmetics: a century of science for kojic acid. Natural Product Reports. DOI:10.1039/B520758A
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Mar 2026.
Report a data errorPhysicochemical Properties
DTXSID: DTXSID2040236
Physical Properties
| Molecular Weight | 142.11 g/mol🔬 EPA CompTox |
| Density | 1.443 g/cm^3📊 OPERA |
| Boiling Point | 319.967 °C📊 OPERA |
| Melting Point | 154.315 °C🔬 EPA CTX |
| Flash Point | 180 °C🔬 EPA CTX |
| Refractive Index | 1.607 Dimensionless📊 OPERA |
| Molar Volume | 92.125 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | -0.64 Log10 unitless🔬 EPA CTX |
| LogD (pH 5.5) | -0.883 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | -1.635 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 7.69 Log10 unitless📊 OPERA |
| Water Solubility | 1.952 mol/L📊 OPERA |
| Henry's Law Constant | 0 atm-m3/mole📊 OPERA |
Transport Properties
| Vapor Pressure | 0 mmHg📊 OPERA |
| Surface Tension | 58.191 dyn/cm📊 OPERA |
Molecular Descriptors
| Topological Polar Surface Area | 70.67 Ų💻 Computed |
| H-Bond Donors | 2 count💻 Computed |
| H-Bond Acceptors | 4 count💻 Computed |
| Rotatable Bonds | 1 count💻 Computed |
| Aromatic Rings | 1 count💻 Computed |
| Molar Refractivity | 31.813 cm^3/mol📊 OPERA |
| Polarizability | 12.612 Å^3📊 OPERA |
Data Sources:
🔬 EPA Experimental data from U.S. EPA CompTox Chemicals Dashboard & CTX APIs. 📊 OPERA Predicted using EPA's OPERA QSAR models. 💻 Computed Calculated from SMILES using RDKit.
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