Oxidized dextran improves the stability and effectively controls the release of curcumin loaded in soybean protein nanocomplexes.

Dextran dialdehyde (ODex) was added to a nanocomplex of soy protein isolate (SPI)-curcumin (Cur) to improve its stability and achieve controlled release of Cur. The SPI-to-ODex mass ratio was optimized to achieve excellent properties and stability. Interactions between various components were confirmed by spectroscopic analysis, and the effect of ODex on the stability and bioactivity of SPI-Cur colloids was discussed. ODex was found to be crosslinked with SPI via the Schiff base reaction, which increased the ζ-potential and improved the surface hydrophobicity of nanocomplexes. At a SPI-to-ODex mass ratio of 20:1, the nanocomplex had a smaller particle size (199.2 nm), higher ζ-potential (-45.48 mV), and higher encapsulation efficiency (96.25%). Furthermore, adding ODex changed the network structure and effectively improved the thermal and storage stability of Cur as well as its antioxidant properties. Moreover, controlled release of Cur was observed during simulated digestion in the gastrointestinal environment.