How Emulsifiers Work
Emulsifiers are molecules that have two distinct ends. One end likes to be in water (hydrophilic) and the other end likes to be in oil (lipophilic). This means that they will coat the surface of oil droplets in an oil-in-water emulsion and effectively 'insulate' the oil droplets from the water. It keeps them evenly dispersed throughout the emulsion and stops them from clumping together to form their own, separate layer.
In a water-in-oil emulsion, the emulsifier coats the water droplets to stop them from separating from the oil.
This property makes emulsifiers indispensable in the modern food industry where foams, suspensions (particles of solid dispersed evenly through a liquid) and emulsions are often used.
Milk is a natural emulsion. It is a mixture of fat droplets in water. Proteins in the milk help to coat the fat droplets and allow them to stay dispersed in the water of the milk.
Run the animations to see what happens to an emulsion if an emulsifier is not present.
|Oil and Water: No Emulsifier||Oil and Water: With Emulsifier|
Origin and manufacture of emulsifiers
The most common type of emulsifiers used are lipids called monoglycerides. These are produced by reacting fatty acids with glycerol. Most of the other emulsifiers are produced by the esterification of other materials, such as lactic acid with mono- and di-glycerides. Natural sources like vegetable oils and animal fats are often used to make emulsifiers.
The most commonly used emulsifiers are lecithin (E322) and the mono- and
di-glycerides of fatty acids (E471). There are many other emulsifiers in use. Without the use of emulsifiers, many foods would be inedible.