Interfacial adsorption of soybean phosphatidylethanolamine in different oil phase and the stability of water-in-oil emulsion

Water-in-oil (W/O) emulsion holds great potential in designing fat-reduced foods. However, due to the lack of W/O-type surfactant, formation of all-natural W/O emulsion is challenged. This study aimed to investigate the effect of oil phase on interfacial adsorption of soybean phosphatidylethanolamine (SP) and stability of W/O emulsion. Five oils, including medium chain triglycerides oil (MO), coconut oil (CO), palm kernel oil (PKO), sunflower oil (SO) and rapeseed oil (RO), were selected. Results showed that diffusion rate of SP to the interface ranked as MO > CO > PKO > SO approximate to RO, increasing interfacial adsorption from 50.2 % to 85.3 %. Higher interfacial adsorption improved the deformation resistance of interfacial layer, causing more significant decrease in interfacial tension (3.54 mN/m). So, the largest water fraction (65 %) was stabilized by SP with MO and CO, and exhibited smaller droplet sizes and better stability. Consequently, shorter-chain oil was more suitable for preparing W/O emulsions.