Glyceryl monostearate is an ester derived from stearic acid and glycerin. It is a non-ionic surfactant commonly used in the cosmetic, pharmaceutical, and food industries for its emulsifying, stabilizing, and solubilizing properties. It is used to combine ingredients that would otherwise not mix easily, such as water and oils, forming stable emulsions in creams, lotions, and other products.

Chemical Composition and Structure

Glyceryl monostearate is formed through the reaction between a glycerin molecule and stearic acid, a long-chain fatty acid. Its chemical structure consists of:

• Glycerin Backbone: Glycerin is a trihydroxy alcohol that serves as the base for ester formation.
• Stearic Acid: Stearic acid is a saturated fatty acid that, when combined with glycerin, forms the glyceryl monostearate ester.
• Ester Link: The stearic acid is bonded to the glycerin via an ester link, giving glyceryl monostearate its emulsifying properties.

Physical Properties

• Appearance: White or slightly yellowish solid.
• Odor: Mild, neutral.
• Solubility: Insoluble in water but soluble in oils and organic solvents.
• Melting Point: The melting point ranges between 55–60°C.
• Stability: Stable under neutral or slightly acidic pH conditions; its stability decreases in highly acidic or alkaline environments.

Production Process

• Synthesis: Glyceryl monostearate is produced through esterification, a chemical process that combines glycerin and stearic acid under heat and in the presence of a suitable catalyst.
• Purification: After synthesis, the compound is purified to remove unwanted by-products and obtain the final product as a white powder or granules.
• Standardization: The final product is standardized to ensure consistent emulsifying and stabilizing properties across applications.

Applications

Medical Applications

• Emulsifier in pharmaceutical formulations: Used in creams, ointments, and lotions to improve miscibility and stabilize formulations containing both aqueous and oily ingredients.
• Vehicle for topical drugs: Helps improve the penetration of active ingredients into the skin and ensures their stability in the formulation.

Cosmetics

• Emulsifier and stabilizer: One of the most common emulsifiers used in cosmetics, it is used to combine water and oils in formulations like face creams, lotions, body butters, and shampoos.
• Moisturizing: Contributes to keeping the skin soft and hydrated by forming a barrier that reduces moisture loss.
• Skin softening properties: Adds a silky, smooth texture to cosmetic products, enhancing skin feel.

Food Industry

• Food additive: In food production, glyceryl monostearate is used as an emulsifier to improve texture and stability in products like margarine, ice cream, and sauces.
• Stabilizing agent: Helps prevent ingredient separation, ensuring a consistent texture.

Environmental and Safety Considerations

• Biodegradability: Glyceryl monostearate is generally considered biodegradable and safe for the environment when used at appropriate concentrations.
• Safety Profile: Generally regarded as safe for use in cosmetics and food, but may cause skin irritation in sensitive individuals. If adverse reactions occur, it is recommended to discontinue use of the product containing glyceryl monostearate.
• Sustainability: It is typically produced from plant-based sources, though sustainability depends on the quality of the raw materials and production processes used.

Molecular Formula  C₂₁H₄₂O₄

Molecular Weight   358.6 g/mol

CAS     123-94-4

UNII    258491E1RZ

EC Number  293-208-8    250-705-4

Synonyms:

Monostearin

Glyceryl monostearate