Interfacial rheology of protein-surfactant mixtures

The distribution of proteins and surfactants at fluid interfaces (air-water and oil-water) is determined by the competitive adsorption between the two types of emulsifiers and by the nature of the protein-surfactant interactions, both at the interface and in the bulk phase, with a pronounced impact on the interfacial rheological properties of these systems. Therefore, the interfacial rheology is of practical importance for food dispersion (emulsion or foam) formulation, texture, and stability. In this review, the existence of protein-surfactant interactions, the mechanical behaviour and/or the composition of emulsifiers at the interface are indirectly determined by interfacial rheology of the mixed films. The effect on the interfacial rheology of protein-surfactant mixed films of the protein, the surfactant, the interface and bulk compositions, the method of formation of the interfacial film, the interactions between film forming components, and the displacement of protein by surfactant have been analysed. The last section tries to understand the role of interfacial rheology of protein-surfactant mixed films on food dispersion formation and stability. The emphasis of the present review is on the interfacial dilatational rheology. (C) 2009 Elsevier Ltd. All rights reserved.