Ultrasound-assisted heat treatment: Accelerating rice glutelin fibrils formation and enhancing emulsifying properties

The self-assembly of rice glutelin (RG) into RG fibrils (RGFs) represents a promising strategy for enhancing its functional properties. In this study, we investigated the effects of ultrasonic pretreatment on the fibrillation kinetics, structural characteristics, and functional properties of RGFs. The results indicated that ultrasonic pretreatment facilitated the unfolding of RG, resulting in an increased H₀ and β-sheet, thereby accelerating the formation of RGFs and enhancing the fibril conversion rate. Thioflavin T fluorescence spectroscopic analysis confirmed the formation of numerous cross β-sheet structures following 4 h of heating; however, ultrasonic pretreatment reduced this duration to just 2 h. Additionally, the ζ-potential and solubility of RGFs were significantly improved following ultrasonic pretreatment. TEM revealed that the URG-6 fibril sample exhibited the smallest diameter (3.81-5.27 nm) and greatest length (1109.92-1946.21 nm), demonstrating a high aspect ratio. Furthermore, ultrasonic pretreatment enhanced the emulsifying properties of RGFs, with the URG-6 emulsion achieving the highest EAI (147.61 m²/g) and ESI (134.67 min), along with the smallest droplet sizes. This study provides the basis for the development of RGFs and broadens their application in the food industry.