Improvement of the encapsulation capacity and emulsifying properties of soy protein isolate through controlled enzymatic hydrolysis

Self-assembling nanoparticle made from soy protein hydrolysates has proved to be a promising delivery system due to its excellent biocompatibility and synthetic feasibility. In this study, the critical parameters that control the SPI hydrolysate structure and its encapsulation capacity have been assessed. Three different enzymes, including Flavorzyme, Neutrase and Alcalase, were selected to hydrolyze soy protein isolate (SPI), and a solvent evaporation method was used to fabricate β-carotene loaded nanoparticles. Microstructure observation, SDS-PAGE, surface hydrophobicity, and endogenous fluorescence analysis were carried out to examine the key structural factors influencing encapsulation efficiency of SPI hydrolysates nanoparticles (SPIHs). It was found moderate exposure of hydrophobic amino acids inside the 7 S globulin via Flavorzyme controlled hydrolysis can increase the surface hydrophobicity of SPIH, therefore improving its emulsifying properties, while excessive hydrolysis of 7 S by Alcalase would cause weak hydrophobic interactions between the hydrophobic amino acids, which restricted the binding site with β-carotene. Above results provide a foundation for fabricating nanoparticles encapsulating lipophilic compounds with high encapsulation rate from SPI hydrolysates (SPIH).