Emulsification Emulsifying Emulsion

If you pour a small amount of oil into a glass of water, it is not normally possible to mix the oil with the water. Oil is the lighter of the two liquids. After shaking, the oil bubbles rise from the water and settle as a layer of oil on top of the water.

Emulsifying means converting such immiscible liquids into a stable mixture. This can be achieved by transferring the oil into extremely small droplets. The droplet size can be in the micrometre or even nanometre range. Such small droplets are formed when oil and water are mixed with extremely high shear energy. The smaller the oil droplets are, the more transparent such a mixture is.

In this case, we speak of an oil-in-water emulsion. Conversely, one would speak of a water-in-oil emulsion.

The emulsification process can be accelerated by adding an additive. For example, lecithin can act as an emulsifier as it is soluble in both fat and water. Surfactants can also be emulsifiers. Emulsions can be stable or segregate. Cellulose ether or pectin can be added to counteract segregation. Examples of emulsions are body lotion, sun cream, milk, mayonnaise or lubricants. Emulsions are produced with the aid of high-speed rotor-stator liquid mixers or colloid mills.