Oil and water don’t mix but they do form emulsions – and these are crucial to the consistency of a number of foodstuffs. Nature is good at making emulsions, and the classic example is milk, where a complex mixture of fat droplets are suspended in an aqueous solution.
Emulsifiers are the chemicals that make emulsions happen. Nature uses proteinsCompounds that contain the elements carbon, hydrogen, oxygen... and phospholipidsLipids containing two fatty acid units and one phosphate gro..., and many emulsifiers used in modern food production are based on these natural substances.
An emulsifierA substance which allows an emulsion to stay in a stable sta... is a molecule in which one end likes to be in an oily environment and the other in a water environment. To make an oil-in-water emulsionTiny drops of one liquid spread evenly through a second liqu..., such as mayonnaise, droplets of oil molecules are surrounded by the oil-loving end of the emulsifierA substance which allows an emulsion to stay in a stable sta... molecules. This leaves the water-loving ends on the outside of the droplet, and so they sit happily in water, giving a homogeneous liquid rather than an unappealing mixture of water and oily droplets. In mayonnaise, the emulsifierA substance which allows an emulsion to stay in a stable sta... is the phospholipidsLipids containing two fatty acid units and one phosphate gro... present in egg yolks – they are such successful emulsifiers that as much as 80% oil can be dispersed in the aqueous phase.
Ice cream is another food that would not exist were it not for emulsifiers. It is both a foamThe dispersal of a gas in a liquid. and an emulsionTiny drops of one liquid spread evenly through a second liqu..., and its texture results from the ice crystals and unfrozen water it contains. But it’s not just creamy products where emulsifiers are crucial – bread and other baked products, where solid particles are dispersed in an airy foamThe dispersal of a gas in a liquid., are enhanced by emulsifiers.
The emulsifiers that are used commercially come from both natural and synthetic sources. They include:
Lecithins (E322) are mixtures of phospholipidsLipids containing two fatty acid units and one phosphate gro... such as phosphatidyl choline and phosphatidylethanolamine, and are usually extracted from sources such as egg yolk and soybeans. The precise composition of the phospholipidsLipids containing two fatty acid units and one phosphate gro... depends on the source. Uses include salad dressings, baked goods and chocolate.
Esters of monoglycerides of fatty acids (E472a-f) are made from natural fatty acids, glycerolA sweet, sticky liquid containing three alcohol groups; it c... and an organic acid such as acetic, citric, lactic or tartaric. The fatty acids are usually from a vegetable source, though animal fatsCompounds which contain the elements carbon, hydrogen and ox... can be used. Products that use them include ice cream, cakes and crisps.
Mono- and diglycerides of fatty acids (E471) are semi-synthetic emulsifiers made from glycerolA sweet, sticky liquid containing three alcohol groups; it c... and natural fatty acids, which can be from either plant or animal sources. They are used in products like breads, cakes and margarines.
