Assessing stability and delivery performance of oleogel-based Pickering emulsions stabilized by gallic acid-modified hordein nanoparticles: Analysis of the differences between covalent and non-covalent interactions.

The modification of protein nanoparticle properties by polyphenols is related to their interaction ways. Hordein was covalently and non-covalently modified with gallic acid (GA), respectively, and assembled into nanoparticles to stabilize oleogel-based Pickering emulsions (OPEs) for the purpose of comparing their properties and stabilization mechanisms. GA covalently grafted improved the wettability of hordein nanoparticles, facilitating the formation of smaller droplets and thus enhancing emulsion stability. In contrast, OPEs stabilized by non-covalent hordein-GA nanoparticles (NC-NPs) formed a network structure through bridging between nanoparticles, thereby improving emulsion stability. Regarding curcumin protection, covalent hordein-GA nanoparticles (C-NPs) exerted better protection effects due to more effective localization of GA at the oil-water interface. In vitro and in vivo experiments demonstrated that C-NPs contributed to the rapid release of curcumin from OPEs, whereas NC-NPs contributed to the slow release of curcumin from OPEs. This study would facilitate the development of polyphenol-modified hordein in Pickering emulsions.