Emulsifiers form a large group of compounds whose function is to stabilise mixtures of two immiscible liquids. In the food context, the immiscible liquids are normally oil (fat) and water. Emulsifiers are effective at very low levels so are classed as minor ingredients or food additives. In biscuit doughs an emulsifier permits the easier blending of a fat in the dough and this effect also results in possibilities of reduced fat usage to obtain similar biscuit textural properties.

Most of the emulsifiers are synthesised chemicals and there are legal restrictions for their use in food. Naturally occurring emulsifiers are few and only lecithin, derived principally from soya bean, is in common usage. However, for about 50 years the value of specially prepared monoglycerides, such as glycerol monostearate, products of fat refining, have been used. Glycerol monostearate is a white flaky substance.

Lecithin is a natural food substance which occurs in all living matter but is found in significant quantities in egg yolk (8-10%) and soya beans (2.5%) which is the main source of vegetable lecithin. It is extracted from the beans by solvents, but varies in composition and always contains a sizeable percentage of soya oil. It is a fluid or a plastic paste and is normally supplied in steel drums.

There is a great range of other emulsifiers available for use in baked products. Most are specific in their function and all need to be declared in the ingredient list on the packaging of the products. Users are recommended to obtain application help from the suppliers.

Margarines which contain water usually have an emulsifier added at the time of manufacture. It is not necessary to add more emulsifier when this form of fat is used to make a dough.