The effects of ultrasound-assisted glycosylation modification on zein protein structure and resveratrol grafting

Zein possesses a unique amphiphilic structure and excellent biocompatibility, making it a natural carrier of bioactive substances with significant development potential in the food sector. However, its extremely poor water solubility has limited its scope of application. This study aims to optimize the structure of zein through ultrasound-assisted glycosylation and resveratrol grafting. The results indicated that mild ultrasonic treatment effectively exposed active amino acid groups in zein, promoted the glycosylation degree of zein, improved protein solubility, and enhances the grafting efficiency of resveratrol. In particular, 100 W ultrasonic treatment resulted in the highest glycosylation degree (40.0%) and protein solubility (18.36 mg/mL) for zein, while reducing the hydrophobic index by 46%. Following resveratrol grafting, the glycosylated nanoparticles treated with 100 W sonication exhibited the smallest particle size (15.56 nm), the highest grafting degree (90.32%) and the maximum solubility (28.47 mg/mL). This modification induced the loss of ordered secondary structures (β–sheets) and yielded significantly higher 2,2′-azobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS• + ) scavenging activity and 2,2- diphenyl-1-pyridylhydrazine (DPPH) scavenging activity activities compared with zein–resveratrol nanoparticles. Both glycosylation and resveratrol-grafting modifications rendered the zein surface smooth, with a continuous and dense structure. This study aims to provide a theoretical basis for the preparation process of zein nanoparticles modified by multiple methods and to expand their applications.