Food Chemistry and Fish in Nutrition ( 2+1)

12.1.2. Emulsifiers

1.      Emulsifiers

 An emulsifier is a substance which stabilizes an emulsion by increasing their kinetic stability. Emulsifiers allow water and oils to remain mixed together in an emulsion. There are two types of emulsions.

1.      Oil-in-water emulsion: It contains small droplets of oil that are dispersed in water.

2.      Water-in-oil emulsion: It has small droplets of water that are dispersed in oil. Usually the water and oil will not mix and the emulsifier, or emulsifying agent, keeps the mixture stable and prevents the oil and water from separating into two layers.

One class of emulsifiers is known as surface active substances, or surfactants.

Use: Emulsifiers are among the most frequently used types of food additives. They are used for many reasons. Emulsifiers can help to make a food appealing. The example of the mayonnaise without the emulsifier shows how unappealing it would be if the oil and water separated before it was used. Emulsifiers have a big effect on the structure and texture of many foods. They are used to aid in the processing of foods and also to help maintain quality and freshness. In low fat spreads, emulsifiers can help to prevent the growth of moulds which would happen if the oil and fat separated.

Examples of food emulsifiers:

Egg yolk (where the main emulsifying chemical is lecithin), honey, and mustard, where a variety of chemicals in the mucilage surrounding the seed hull act as emulsifiers; proteins and low-molecular weight emulsifiers are common as well. Soy lecithin is another emulsifier and thickener. In some cases, particles can stabilize emulsions as well through a mechanism called Pickering stabilization. Both mayonnaise and Hollandaise sauce are oil-in-water emulsions that are stabilized with egg yolk lecithin.

Table 12.2.1 Foods that Commonly Contain Emulsifiers

Biscuits	Toffees	Bread
Extruded snacks	Chewing gum	Margarine / low fat spreads
Breakfast cereals	Frozen desserts	Coffee whiteners
Cakes	Ice-cream	Topping powders
Desserts / mousses	Dried potato	Peanut butter
Soft drinks	Chocolate coatings	Caramels