Interaction between egg PC vesicles and emulsion droplets

Abstract

It discusses the interaction between phosphohpid vesicles and emulsion droplets, which is an important subject in the fields of food science, biology, and medicine. Especially, the emulsions are used prosperously in the field of food technology. To obtain the stable emulsion, some emulsifier must be added into the system. But, the ionic surfactant is known to have toxicity to living body. So, some bio-surfactants are desirable. This chapter explores the interactions between PC vesicle and hexadecane emulsion by utilizing some colloid chemical techniques, such as dynamic light scattering, electrophoresis and fluorescence measurements. The aggregation process of emulsion droplets after adding phosphatidylcholine (PC) vesicles is investigated by determining the ζ-potential and the enlarging size ratio (P) of emulsion droplets at respective step in 10-4 M LaCl3 aqueous solution. The results show that the PC vesicles approach to the emulsion surface by electrostatic attraction; the vesicles adsorb and collapse on the emulsion surface into a monolayer-like structure. The negative charge on the emulsion surface is neutralized by positive charge on the head group of PC + LaCl3, hence the electrostatic repulsion between emulsion droplets decreases and the aggregation of emulsion droplets easily occurs. When the ζ-potential reaches to zero, the aggregation behavior shows a maximum. At higher PC concentration than this, the emulsion surface is covered with large amounts of PC + LaCl3, and the aggregation is prevented by the electrostatic repulsion between the PC adsorbed layer. It also demonstrate that aggregation behavior could be explained well by using the DLVO theory.