Therefore, emulsifiers are attracted to both polar and nonpolar compounds.

A type of surfactant (see Sidebar), emulsifiers contain both a hydrophilic (water-loving, or polar) head group and a hydrophobic (oil-loving, or nonpolar) tail. Today, a wide variety of nature-based and synthetic emulsifiers are available for the diverse fields that benefit from them, including food, nutraceuticals, home and personal care, biofuel, environmental cleanup, and industrial lubricant applications.Įmulsifiers work by forming physical barriers that keep droplets from coalescing.

For centuries, cooks have added natural emulsifiers, such as egg yolk, mustard, or honey, to help prevent this separation. However, in the absence of emulsifiers, this unstable emulsion breaks down within minutes, and the oil forms a layer on top of the vinegar. In both cases, emulsifiers are needed to prevent the suspended droplets from coalescing and breaking the emulsion.Īnybody who has made a simple oil-and-vinegar salad dressing knows that, with enough shaking or whisking, one can make a temporary emulsion. In contrast, margarine is a w/o emulsion containing droplets of water or skim milk in a blend of vegetable oils and fat.

Milk is an example of an o/w emulsion, in which the fat phase or cream forms tiny droplets within the skim milk, or water phase. Simple emulsions are either oil suspended in an aqueous phase (o/w), or water suspended in oil (w/o). These examples represent emulsions, which are stable mixtures of tiny droplets of one immiscible fluid within another, made possible by chemicals called emulsifiers. The immiscibility of oil and water has inspired the proverb “Oil and water don’t mix” and other expressions that reflect the general incompatibility of two entities, such as “My coworker and I are like oil and water.” Yet within our homes are numerous examples of products in which oil and water do mix: mayonnaise, milk, salad dressings, hand lotion, and hair conditioner, to name but a few. how emulsifiers are used in foods, nutraceuticals, personal and home care products, industrial lubricants, environmental technologies, biofuels, and other applications.

how formulators choose which emulsifier to use for a particular emulsion.After reading this article, you will understand:

Emulsion surface chemistry