Abstract: An emulsifier is a substance that mixes (disperses) two immiscible liquids (oil and water) to form a homogeneous dispersion (emulsion). Emulsifiers are usually amphiphilic molecules which can form a monomolecular layer at the interface of two immiscible liquids and reduce their interfacial tension. The addition of emulsifiers can promote the formation of the emulsion and improve its stability and functionality. Emulsifiers can be divided into natural emulsifiers and synthetic emulsifiers according to their sources. Considering the safety of synthetic emulsifiers and the limited stability of a single natural emulsifier, two or more emulsifiers should be blended to improve the functionality of each emulsifier alone. This article reviews the mechanism of single and mixed emulsifiers for stabilizing emulsions. Mixed emulsifiers work by changing the force between oil droplets and the competitive adsorption between the individual emulsifiers. Furthermore, the binding mode and mechanism of protein-polysaccharide composite emulsifiers. This review will lay a theoretical foundation for the application of single and mixed emulsifiers in emulsions.

Key words: emulsion; emulsifier; emulsification mechanism; emulsion stability; mixed emulsifiers; competitive adsorption