Lactic acid (CAS 50-21-5) — Sweet Not typically used as fragrance Note Fragrance Ingredient
Lactic acid
CAS 50-21-5
What Is Lactic acid?
Lactic acid is a naturally occurring organic acid found in sour milk, pickled vegetables, and human sweat. It’s widely used in food preservation, skincare products, and as a pH regulator. This versatile compound matters because it’s both a key metabolic substance and an important industrial chemical, bridging biological processes and manufactured products.
Safety Profile
GENERALLY SAFEWhat Does Lactic acid Smell Like?
Lactic acid presents a sharp, sour odor reminiscent of spoiled milk or fermented dairy, with a slightly cheesy undertone. The scent profile is straightforward without much evolution – it maintains its acidic character throughout, though high dilutions can reveal a faintly sweet, almost yogurt-like nuance in the drydown.
2D Molecular Structure
SMILES: CC(O)C(O)=O
Chemistry, Properties & Perfumer Guide
The Chemistry
Lactic acid (2-hydroxypropanoic acid) is a chiral α-hydroxy acid with two enantiomers. The L-form is biologically important in muscle metabolism. Industrially produced via bacterial fermentation of carbohydrates or chemical synthesis from acetaldehyde. Shows typical carboxylic acid reactivity and forms lactide dimers when heated.
Physical & Chemical Properties
| Boiling Point | 122 °C (15 mmHg) |
|---|---|
| Melting Point | 16.8 °C (L-isomer) |
| Density | 1.206 g/cm³ (20 °C) |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Skincare | 5-10% | Up to 30% | As exfoliant/pH adjuster |
| Food | 0.1-2% | GMP | Acidulant/preservative |
Classic Accords
Tip: Use as pH adjuster rather than fragrance component.
Alternatives & Comparisons
Smaller AHA with greater skin penetration for cosmetic formulations requiring deeper exfoliation.
Alternative acidulant with brighter, fruitier notes for food applications where lactic’s dairy connotations are undesirable.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. Consult current IFRA Standards Library before formulating.
IFRA Status
No IFRA restrictions – not classified as fragrance material
GHS Classification
RIFM Assessment
Not evaluated by RIFM as not used in fragrance applications.
Sustainability
Most lactic acid is now produced sustainably via fermentation of agricultural byproducts. The bio-based production has largely replaced older petrochemical routes, reducing environmental impact. Fermentation-derived lactic acid is considered renewable and biodegradable.
Explore Lactic acid
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References
- PubChem Compound Summary for CID 612 PubChem 612
- Martínez et al. (2017). Lactic acid properties. Food Chemistry.
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.
Report a data errorPerfumer’s Notes
Odor: [‘buttery’, ‘sour’]
MW: 90.08
LogP: -0.7
Ingredient Data Sheet
CAS 50-21-5Physical Properties
| Molecular Weight | 90.08 g/mol🔬 PubChem |
| LogP (Octanol-Water) | -0.7🔬 PubChem |
| Boiling Point | 122 °C🔬 EPA CompTox |
| Vapor Pressure | 0.08 mmHg @ 25°C📊 OPERA |
| Flash Point | 45 °C🔬 EPA CompTox |
| Involatility Index | 0.0091💻 Calculated |
| log Kp (skin permeability) | -3.746💻 Calculated |
| SMILES | CC(C(=O)O)O🔬 PubChem |
Volatility & Performance
| Fragrance Note | Top💻 Calculated |
| Volatility Class | Very slow💻 Calculated |
| Persistence Score | 0.8 / 5💻 Calculated |
Odor & Flavor
| Primary Descriptors | buttery• leffingwell |
| Functional Groups | alcohol💻 RDKit |
| “Chemically pure Lactic acid is odorless, but commercial grades have a faint odor reminiscent of Buttermilk (a "reverse" odor description).”📖 Arctander | |
Flavor Notes (Arctander)
| “tion but probably the closest and most common one). The taste is pleasantly acid in proper dilution. It should be kept in mind that Lactic acid when undiluted is corrosive to human skin, and dissolves many types of organic tissue. It finds extensive use in flavors, partly as a component in certain i”📖 Arctander |
Sensory Thresholds
| Odor Detection Threshold | 9 ppm📖 van Gemert |
Regulatory Status
| FEMA Number | FEMA 2611⚖️ FEMA GRAS |
| GRAS Status | Generally Recognized as Safe⚖️ FEMA GRAS |
Physical data: PubChem (NIH/NLM), U.S. EPA CompTox Dashboard, EPA OPERA models, RDKit. Odor & flavor: Arctander (Perfume & Flavor Chemicals), Fenaroli's Handbook of Flavor Ingredients, Leffingwell. Thresholds: van Gemert (Compilations of Odour Threshold Values). Regulatory: IFRA Standards 51st, FEMA GRAS. Trade names: Surburg (Common Fragrance & Flavor Materials). All data compiled and cross-referenced for perfumertools.com.
Physicochemical Properties
DTXSID: DTXSID7023192
Physical Properties
| Molecular Weight | 90.078 g/mol🔬 EPA CompTox |
| Density | 1.2 g/cm^3🔬 EPA CTX |
| Boiling Point | 204.2 °C🔬 EPA CTX |
| Melting Point | 26.747 °C🔬 EPA CTX |
| Flash Point | 115.523 °C🔬 EPA CTX |
| Refractive Index | 1.451 Dimensionless📊 OPERA |
| Molar Volume | 70.564 cm^3/mol📊 OPERA |
Partition & Solubility
| LogP (Octanol-Water) | -0.687 Log10 unitless🔬 EPA CTX |
| LogD (pH 5.5) | -2.479 Log10 unitless📊 OPERA |
| LogD (pH 7.4) | -4.164 Log10 unitless📊 OPERA |
| LogKoa (Octanol-Air) | 6.72 Log10 unitless📊 OPERA |
| Water Solubility | 11.096 mol/L🔬 EPA CTX |
| Henry's Law Constant | 0 atm-m3/mole🔬 EPA CTX |
Transport Properties
| Vapor Pressure | 0.081 mmHg🔬 EPA CTX |
| Viscosity | 7.269 cP📊 OPERA |
| Surface Tension | 39.589 dyn/cm📊 OPERA |
| Thermal Conductivity | 172.633 mW/(m*K)📊 OPERA |
Molecular Descriptors
| Topological Polar Surface Area | 57.53 Ų💻 Computed |
| H-Bond Donors | 2 count💻 Computed |
| H-Bond Acceptors | 2 count💻 Computed |
| Rotatable Bonds | 1 count💻 Computed |
| Aromatic Rings | 0 count💻 Computed |
| Molar Refractivity | 19.006 cm^3/mol📊 OPERA |
| Polarizability | 7.534 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.
