Method for loading liposomes with soybean protein isolate hydrolysate influences the antioxidant efficiency of liposomal systems: Adding after liposomes formation or before lipid film hydration

This research investigated the method for loading liposomes with soybean protein isolate hydrolysate (SPIH) to create stable and antioxidative protein hydrolysate-containing liposomes. SPIH (SPIH-AF) prepared via a twostep hydrolysis by alcalase and flavourzyme was added at different concentrations to liposomes by two methods. More effective adsorption of SPIH-AF onto liposomal membrane occurred when it was added at 0.5 mg/ mL and distributed in both the inner and outer water phases (addition before lipid film hydration), or added at lower concentrations (< 0.192 mg/mL) and distributed in the outer water phase (addition after liposomes formation). SPIH-AF concentration and distribution directly influenced its early rate of inhibition on lipid oxidation and membrane properties. SPIH-AF in the outer water phase functioned more effectively to inhibit lipid oxidation products accumulation. The interactions between SPIH-AF and liposomes altered SPIH-AF's secondary structures. Compared with Trp-liposomes interactions, Tyr-liposomes interactions were more sensitive to SPIHAF concentration and distribution. SPIH-AF distribution affected strongly the electrostatic interactions (but weakly the hydrophobic interactions). Tyr/Trp-liposomes interactions were more powerful when SPIH-AF was located in both the inner and outer water phases at higher concentrations.

Automated summary

This study investigated the loading method of SPIH into liposomes and its effects on lipid oxidation and membrane properties. The results showed that SPIH could be more effectively adsorbed onto liposomes at suitable concentrations and distributions, and it altered the secondary structures of liposomes, thereby changing their properties.