Physicochemical and in vitro digestion properties of soy isoflavones loaded whey protein nanoparticles using a pH-driven method

Soy isoflavones are widely used as a dietary supplement. However, the bioavailability of soy isoflavones is low due to the poor water solubility. Whey protein is an excellent biopolymer to encapsulate functional ingredients. In this study, soy isoflavones loaded whey protein nanoparticles were prepared using a pH-driven method. The physicochemical properties and in vitro digestion properties of the nanoparticles were investigated. The results showed that the physicochemical properties of nanoparticles were regulated by the mass ratios of soy isoflavones to whey proteins. Hydrogen bonding and hydrophobic interactions were confirmed in generating soy isoflavones loaded nanoparticles, which modified the thermal stability and secondary structure of whey proteins. The nanoparticles could pass through simulated gastric digestion to deliver soy isoflavones into the intestinal tract, responsible for the increased digestion stability and bioaccessibility of soy isoflavones. Moreover, the controlled release of soy isoflavones from nanoparticles can be achieved with a mechanism of non-Fickian diffusion. This study may provide useful information about the utilization of soy isoflavones loaded whey protein nanoparticles to develop functional foods. • Soy isoflavones loaded whey protein nanoparticles were prepared using a pH-driven method. • Nanoparticles showed high encapsulation efficiency and loading capacity to soy isoflavones. • Thermal stability and secondary structure of whey proteins were modified by soy isoflavones. • Nanoparticles could target delivering soy isoflavones into the intestinal tract. • Digestion stability and bioaccessibility of soy isoflavones were improved by encapsulation.