Fat functionality in emulsified foods
Posted: 28 October 2015 | | 1 comment
An emulsion is a fine dispersion of liquid droplets in another liquid continuous phase in which the droplets are immiscible or insoluble. In food terms, the two phases are generally oils and water. Food emulsions tend to take one of two forms – either oil in water (O/W), e.g. cream and mayonnaise, or water in oil (W/O), e.g. butter and spreads – although more complex duplex emulsions such as water in oil in water (W/O/W) and its opposite oil in water in oil (O/W/O) are also possible. In simplistic terms, water is water but oils can differ in their properties and functionality so what is the best oil to use for a specific food emulsion? In this article, the basic properties of fats that play a role in this choice will be described and how these are important in food emulsions will be discussed.
Functional characteristics of oils and fats
Oils and fats are triglycerides or triacylglycerols and are esters of glycerol with three fatty acid groups. Largely, it is the types of fatty acid and their positioning on the glycerol backbone that define the important functionalities of fats. In terms of fat functionality in emulsified food, three parameters are important:
- physical characteristics, particularly crystallisation and melting
- nutritional characteristics
- storage stability, particularly stability against oxidation and hydrolysis