Emulsion

An emulsion is a mixture of two immiscible (unblendable) substances. One substance (the dispersed phase) is dispersed in the other (the continuous phase). Examples of emulsions include butter and margarine, mayonnaise, the photo-sensitive side of film stock, and cutting fluid for metalworking. In butter and margarine, a continuous lipid phase surrounds droplets of water (water-in-oil emulsion). Emulsions tend to have a cloudy appearance, because the many phase interfaces scatter light that passes through the emulsion.

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Emulsions can suffer from a number of instabilities. Homemade oil and vinegar salad dressing is an unstable emulsion that will quickly separate unless shaken continuously. This phenomenon is called coalescence, and happens when small droplets recombine to form bigger ones. Fluid emulsions can also suffer from creaming, the migration of one of the substances to the top of the emulsion under the influence of gravity or centripetal force when a centrifuge is used.

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Emulsions are part of a more general class of two-phase systems of matter called colloids. Although the terms colloid and emulsion are sometimes used interchangeably, emulsion tends to imply that both the dispersed and the continuous phase are liquid.

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Immiscible: REDIRECT Miscibility...

Butter: Butter is a dairy product made by churning fresh cream. It consists of an emulsion of water and milk proteins in a matrix of fat, with over 80% being fat. It is used as a condiment and for cooking in much the same ways as vegetable oils or lard....

Margarine: Margarine is a generic term used to indicate any of a wide range of butter substitutes. In many parts of the world, margarine is now the best selling table spread, although butter and olive oil also command large market shares. It is used as an ingredient in the preparation of many other foods. Mar...