Emulsions in food are mixtures of oil and water. These normally do not mix and will separate if left without an emulsifier. Roll over the photograph of the mayonnaise to see the effects when the emulsifier is not added.
Mayonnaise contains oil and water. The emulsifier keeps these mixed and without it the oil and water separate.
Roll over the picture to see mayonnaise without emulsifier.
What are emulsions?
There are two types of emulsions. An oil-in-water emulsion contains small droplets of oil that are dispersed in water. Alternatively, a water-in-oil emulsion has small droplets of water that are dispersed in an 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.
Emulsifiers in food
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. The table shows foods in which emulsifiers are most commonly used.
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 |
How Emulsifiers Work
Emulsifiers are molecules that have two distinct ends. One end likes to be in water (hydrophilic) and the other end likes to be in oil (lipophilic). This means that they will coat the surface of oil droplets in an oil-in-water emulsion and effectively ‘insulate’ the oil droplets from the water. It keeps them evenly dispersed throughout the emulsion and stops them from clumping together to form their own, separate layer.
In a water-in-oil emulsion, the emulsifier coats the water droplets to stop them from separating from the oil.
This property makes emulsifiers indispensable in the modern food industry where foams, suspensions (particles of solid dispersed evenly through a liquid) and emulsions are often used.
Milk is a natural emulsion. It is a mixture of fat droplets in water. Proteins in the milk help to coat the fat droplets and allow them to stay dispersed in the water of the milk.
