High protein and high oil emulsions: Phase diagram, stability and interfacial adsorption

Abstract Whey protein isolate (WPI), sodium caseinate (SC) and soy protein isolate (SPI) and three kinds of oils were used to prepare high protein and high oil emulsions. The phase diagrams of the ternary system were constructed after homogenization, sterilization and storage. The results showed that the chain length and saturability of oils had little effect on the storage stability of emulsion. When the oil was 10% MCT, excellent storage stability was achieved by 1–4% WPI-stabilized emulsions, 1–3% and 10% SC-stabilized emulsions, and 1–6% SPI-stabilized emulsions. Nitrogen solubility index and surface hydrophobicity of SPI (39% and 663) were both significantly lower than those of WPI (97% and 1303) and SC (95% and 2207). WPI changed from monolayer adsorption to multilayer adsorption with the protein concentration from 4% to 6%. SC reached saturated adsorption when the protein concentration was higher than 2%. For WPI, β-LG and α-LA decreased significantly with the increase of protein concentration, while small aggregates increased significantly and showed the superiority at 4% content. For SC, the superior position on the interface with the increase of protein concentrations changed from β-casein to α-casein. For SPI, the aggregates exhibited the superior position and increased with the increase of protein concentrations.