Proteins and emulsifiers at liquid interfaces.
The interfacial properties of proteins and emulsifiers have been studied extensively in the field of food colloid research. Emulsions form the basis of a huge range of food products and are generally stabilised by either protein and/or emulsifiers. Proteins have been shown to stabilise emulsions by forming a viscoelastic, adsorbed layer on the oil droplets, which form a physical barrier to coalescence. Emulsifiers can be oil or water soluble, forming a fluid, close-packed layer at the interface with a low interfacial tension. This results in an emulsion with a small droplet size distribution, stabilised by the fluid Gibbs-Marangoni mechanism or weak electrostatic repulsion. In real food emulsions, there is usually a mixture of proteins and emulsifiers competing for the interfacial area. This can produce a finer emulsion, however, the emulsifiers break down the viscoelastic protein-adsorbed layer, resulting in an emulsion with reduced stability. We present a review recent work that aims to characterise the composition, structure and physical properties of mixed protein-emulsifier interfaces, in an effort to understand the mechanisms behind the stability behaviour of food emulsion systems.
Wilde
Peter
P
Institute of Food Research, Norwich Research Park, Colney, Norwich NR4 7UA, UK. peter.wilde@bbsrc.ac.uk
Mackie
Alan
A
Husband
Fiona
F
Gunning
Patrick
P
Morris
Victor
V
D003102:Colloids / Q000737:chemistry*; D004058:Diffusion; D004655:Emulsions / Q000737:chemistry*; D007782:Lactoglobulins / Q000737:chemistry; D008027:Light; D011506:Proteins / Q000737:chemistry*; D055672:Static Electricity; D013997:Time Factors
D003102:Colloids; D004655:Emulsions; D007782:Lactoglobulins; D011506:Proteins