The preparation of plant-based milk substitutes with antioxidant properties using soybean protein isolate and curcumin composite nanoparticles

Abstract

This study produced a nanoemulsion with antioxidant properties using soybean protein isolate-curcumin nanoparticles (SPI-Cur-NPs) as a plant-based milk substitute. The relevant properties of the nanoemulsions were investigated by characterizing the particle size, polydispersity index (PDI), ζ-potential, and loading capacity. Confocal laser scanning microscopy and transmission electron microscopy verified that the emulsion was the O/W type and that the droplet size was approximately 70 nm. After treatment with 63 °C, pH (2.0, 4.5, 9.0), and various concentrations of NaCl at 0, 200, and 500 mM, the nanoemulsions containing 4% SPI-Cur-NPs were stable and homogeneous. Due to the presence of curcumin, thiobarbituric acid-reactive substances were maintained at a level approximately 3.2-fold lower than the control during the 14-day accelerated oxidation experiment, while the peroxide value of this nanoemulsion was maintained at approximately 0.0184 μmol/L during the 30-day storage experiment. Experiments on in vitro digestion revealed that the lipid release rate in the nanoemulsion exceeded 80%, significantly greater than the free state of 27.8%. Hence, nanoemulsions stabilized by SPI-Cur-NPs can be considered a potential plant-based milk substitute that can supplement fat-soluble nutrients and has excellent stability.