Effect of Ultrasonic Pretreatment and EGCG on the Structural and Functional Properties of Rice Protein Amyloid...

Rice protein has great nutritional value and is low in allergens, but their application in the food industry is restricted because they have poor functional properties. This research explored the impact of combining epigallocatechin gallate (EGCG) with ultrasonic pretreatment upon the formation of rice protein amyloid fibrils (RPAFs) and their functional properties. Results revealed that ultrasonic pretreatment primarily induced a transformation in the β-lamellar structure of rice protein, which accelerated the conversion to RPAFs. Ultrasonic-treated RPAFs combined with EGCG (UFE) exhibited the highest viscosity, superior emulsifying and foaming properties, and enhanced antioxidant capacity. Specifically, compared to native protein (P), UFE improved emulsifying activity index (EAI) from 14.3 to 27.3 m²/g and enhanced foaming capacity (FC) from 14.8% to 42.5%. Furthermore, the ABTS⁺ scavenging rate increased from 35.6% to 92.8%, and the DPPH scavenging rate elevated from 53.3% to 92.3%. These findings demonstrate that the combined treatment significantly enhances the functionality of rice protein, offering a potential strategy for its application in functional foods and high-value protein formulations.