Emulsifiers: Lecithin and Proteins

Emulsifiers are molecules that lower the surface tension of one liquid dispersed in another, and therefore make it easier to make small droplets and a fine, creamy emulsion. They do so by coating the surface of the droplets, and shielding the droplet surface from the continuous liquid. Emulsifiers are therefore a true liaison: they must be partly soluble in each of the two mutually incompatible liquids. They manage this by having two different regions on the same molecule, one soluble in water and the other in fat.