Emulsifiers for the Food Industry

Abstract

Emulsifiers are widely used in the food industry. Emulsions are thermodynamically unstable systems consisting of two immiscible phases, such as oil and water, which could be in the form of either oil‐in‐water (o/w) emulsion or water‐in‐oil (w/o) emulsion. Putting mechanical energy into the system (e.g. by mixing) in a way that subdivided one phase will increase the total amount of interfacial area and energy. Thus, the lower the amount of interfacial free energy per unit area, the larger the amount of new interfacial area that can be created for a given amount of energy input. The subdivided phase is called the dispersed phase, and the other phase is the continuous phase. Emulsifiers are more concentrated in the interfacial region than in the bulk solution phase that is amphiphilic in nature, with the lipophilic (or hydrophobic) part of the molecule preferring to be in a lipid (nonpolar) environment and the hydrophilic part preferring to be in an aqueous (polar) environment. Examples of emulsifiers are phospholipids, proteins, polysaccharides, and other surface‐active polymers. This article emphasizes the thermodynamic approach of emulsion and emulsifiers as well as their industrial food applications in detail.