Peter Wilde is a biophysicist by training, who’s research focuses on the colloidal and interfacial properties of food emulsions. Peter is exploring how the dietary impact of emulsified foods can be improved by controlling the basic properties of the emulsions themselves.
The texture of emulsions is controlled not only by the viscosity of the component phases, but also of the interactions between the individual emulsion droplets. For example, when making mayonnaise, adding more oil to the process creates more emulsified oil droplets, and results in a thicker, more viscous product. Our sensory perception of these foods is quite sensitive to changes in fat content, so when the amount of fat is reduced, we perceive the product to be thinner and less creamy etc. and thus of poorer quality. Adding thickeners can help improve the overall texture, but only partially accounts for our perception of fat content. Therefore we need to make the emulsion droplets themselves make the maximum contribution to the perceived fat content.
By strengthening the interactions between the droplets we can get a more viscous, better tasting product with less added fat. By changing the surface of the fat droplets these interactions can be strengthened. Using proteins to form a thick, elastic layer on the surface of the droplets, it is possible to increase the viscosity of the emulsions, and improve the sensory properties.
Another approach is to use multiple emulsions. This is where some of the fat in the emulsion droplets is replaced by water droplets, giving a multiple (water droplets in oil droplets in water) emulsion. This means that we can have the same number and size of emulsions droplets, and thus the same viscosity and texture, but by using less fat.
Exploiting the mechanisms controlling these properties it may be possible for food manufacturers to formulate reduced fat foods with better consumer acceptability.