Rice peptide nanoparticle as a bifunctional food-grade Pickering stabilizer prepared by ultrasonication: Structural characteristics, antioxidant activity, and emulsifying properties.

In this study, a novel food-grade Pickering stabilizer was fabricated from insoluble rice peptide aggregates that are considered undesirable and formed during the hydrolysis of rice protein using ultrasonication. The results confirmed that ultrasonication was effective in fabricating rice peptide nanoparticles (RPNs) with a spherical appearance, and the particle size was reduced with ultrasonic time, reaching a minimum size of 357.8 nm in 30 min. Moreover, ultrasonic treatment could improve the antioxidant activity of RPNs by promoting the DPPH scavenging (3.5-fold increase) and Fe2+ chelating activity (3.8-fold increase). Notably, the bioactive RPNs could form stable Pickering emulsions that possess both physical and oxidative stability during storage, which might be due to the antioxidative physical barrier formed by RPNs. These findings suggest a new approach for the effective utilization of insoluble aggregates produced during protein hydrolysis as well as provide a novel bifunctional Pickering stabilizer with intrinsic antioxidant properties.