An emulsion is a mixture of two or more liquid that is normally unmixable and unblendable. It is a termed used in chemistry. It means that in an emulsion the dispersed phase and dispersion medium are both liquids. There is two basic type of emulsions: oil in water and water in oil. Oil and water don’t mix.
Examples of Emulsions:
- Oil and water mixtures are emulsions when shaken together. The oil will form drops and disperse throughout the water.
- Egg yolk is an emulsion containing the emulsifying agent lecithin.
- Butter is an emulsion of water in fat.
- Mayonnaise is an oil in water emulsion that is stabilized by the lecithin in egg yolk.
Types of emulsion:
There are two types of emulsion:
- Water in oil emulsion: The emulsion in which water forms the dispersed phase, and the oil acts as the dispersion medium is called a water-in-oil emulsion. These emulsions are also termed oil emulsions. Butter and cold cream are typical examples of this types of emulsions. Other examples are cod liver oil etc.
- Oil in water emulsion: The emulsion in which oil is present as the dispersed phase and water as the dispersion medium continuous phase is called an oil-in-water emulsion. Milk is an example of the oil-in-water type of emulsion. In milk liquid fat globules are dispersed in water. Other examples are vanishing cream etc.
An emulsion is a special type of mixture made by combining two liquids that normally don’t mix. Milk Emulsion is considered as a permanent emulsion of the butterfat in water. Casein acts as an emulsifier in Milk Emulsion and butter is said to be an emulsion of water in fats. Milk is an emulsion of fat in water. Butter is an emulsion of water in fat. The solute is known as the dispersed phase and the solvent is known as the continuous phase. The properties of oil-in-water emulsions that are stabilized by milk proteins are determined largely by the nature of the adsorbed layer at the surface of the dispersed droplets.
The emulsion in pharmacy:
A Pharmaceutical Emulsion is a two-phase liquid preparation consisting of two or more immiscible liquids in which small globules of one liquid are dispersed uniformly throughout the other liquid. The emulsion is a biphasic liquids system. They are used for drug delivery in medicine, cleaning of oil and greasy surfaces, storage of substances etc. The routes of medication administration by which emulsions are given include by oral, parenteral and even few topical preparation creams. They are difficult to make and also tough to store them in a stable manner. Pharmaceutical preparations for the treatment of skin conditions and skin care are usually supplied in the form of emulsions. This pharmaceutical dosage form is thermodynamically unstable and must be stabilized by the addition of the emulsifying agent. Pharmaceutical emulsions usually consist of water and an oil. Two main types can exist which is oil in water and water in oil depending upon the continuous phase is aqueous or oily. Emulsions are part of a more general class of two-phase systems of matter called colloids.