Emulsifiers are chemicals that allow oil-based and water-based substances to form a stable mixture, or colloid, rather than separating. On a molecular level, an emulsifier is made up of one end that is water-soluble and one end that is fat-soluble. Emulsifiers can come from either animal or plant sources. The most common types of vegetable emulsifiers include lecithin, biosurfactants and vegetable emulsifying wax.
Lecithin is a fatty acid found in cell membranes and cell walls. It was originally isolated from egg yolks. By the late 20th century, however, most commercial lecithin was extracted from vegetable sources, such as soybeans, coconut oil or palm oil.
In food production, lecithin-based vegetable emulsifiers have a variety of uses. Most often, they keep the various ingredients in food from separating over time. The oils in peanut butter, for instance, will often rise to the top of the jar without the aid of some sort of vegetable emulsifier. On the other hand, brominated vegetable oils are often added as a clouding agent to liquids, such as fruit juices that are already stable.
Surfactants, or surface-active agents, are a class of emulsifiers that work by reducing surface tension in water and oil molecules. Both commercial and household cleaning agents often use surfactants, which can dissolve the bonds between surfaces and contaminants. Most surfactants are petroleum-based, which many believe have a strongly negative environmental impact. Scientists in the late 20th and early 21st century, however, were beginning to produce various types of organic surfactants, or biosurfactants, from plant sources. Vegetable emulsifiers that work as surfactants can be extracted from vegetable oils in much the same way that lecithin is produced.
Vegetable emulsifiers can also be made into waxes that are used in cosmetics to suspend pigments within a water or oil base. Cosmetics often contain animal-based emulsifiers that some consumers find objectionable. Vegetable emulsifying wax can be a viable alternative for some people, although others may object to trace amounts of artificial chemicals that may be found in the wax.