Emulgators

Emulgators, also known as emulsifiers, are substances that stabilize emulsions by reducing interfacial tension between immiscible liquids and by forming protective interfacial films around droplets. They enable droplets of oil to be dispersed within water or vice versa.

They are typically surface-active agents with both hydrophilic and lipophilic regions. They can be nonionic, anionic, cationic, or amphiphilic polymers. They work by lowering interfacial tension and by creating a barrier that prevents droplets from coalescing, through electrostatic repulsion or steric hindrance.

Common examples include food-grade lecithin, mono- and diglycerides, and polysorbates; in cosmetics and personal care, polysorbates and sorbitan esters are common; in baking and dairy, proteins like casein and egg are natural emulsifiers. In industrial applications, polymeric or natural emulsifiers are used.

Emulsions have types such as oil-in-water and water-in-oil, chosen based on the system. Emulsifier selection depends on the required emulsion type and the HLB value. Some emulsifiers provide primarily electrostatic stabilization; others rely on bulky molecules to form a steric barrier.

Applications span food, cosmetics, pharmaceuticals, and paints. Regulation varies by jurisdiction; many emulsifiers are approved for specific uses and have maximum permitted levels. Safety considerations include potential allergenicity and interactions with other ingredients.

Stability of emulsions depends on multiple factors beyond the emulsifier, including processing, pH, ionic strength, temperature, and storage. Emulgators are a central tool in formulation science for managing texture, appearance, and shelf life.