Preparation and characterization of soybean protein isolate-dextran conjugate-based nanogels.

Soybean protein isolate (SPI)-dextran conjugate-based nanogels were prepared via the Maillard reaction combined with protein self-assembly in this study. The dextran molecular weight (40 kDa), SPI/dextran mass ratio (1:1.75), and incubation time (3.3 d) for preparing SPI-dextran conjugate (SDC) were firstly optimized. The SDC was confirmed by analyzing the changes in protein composition and infrared absorption bands and showed loosened tertiary conformation, reduced surface hydrophobicity, decreased Z-average hydrodynamic diameter (D) and zeta potential, and improved emulsifying properties compared to the native SPI. Effects of conjugate concentration, pH, heating temperature, and time on D and polydispersity index were also evaluated. The SDC-based nanogels were translucent in aqueous solution and exhibited a spherical core-shell structure with a D of ∼104.4 nm and a good stability against thermal treatment, ionic strength, and storage. Results demonstrated the SDC-based nanogels possessed a potential to be used as desirable nanocarriers for encapsulating hydrophobic bioactive compounds.