Microcapsules with condensates and liposomes composite membranes fabricated via soy protein simple coacervation

Coacervation is a common phenomenon in plant proteins which however has yet been well recognized. This study systematically investigated the properties of soy glycinin coacervates, explored the wetting behavior between the condensates and oil droplets in order to obtain microcapsules with core-shell structure, and furthermore figured out the strategy to stabilize the condensate membranes. Fluidity of glycinin coacervates was characterized by viscosity and fluorescence recovery after photo bleaching which was highly dependent on solution parameters and intriguingly increased with prolonged time due to protein structure reorganization. Complete engulfment of oil droplets by coacervates leading to core-shell structure formation was achieved at salinity≥0.1M NaCl and pH ≥ 7 above room temperature. Core-shell structure could be preserved by membranization using liposome coating as it prevented the coalescence between coacervates. Condensate membranes were further hardened by a combination of physical and enzymatic crosslinking using calcium ions and transglutaminase respectively which enabled the microcapsules to survive in the gastric environment. This study is important as it paves way for fabricating well designed microcapsules based on the simple coacervation of plant proteins which are biocompatible and widely abundant.