Fibrils aggregation induced the conformationally flexible regions of rice bran protein to improve its stability of emulsion gel

Abstract

Rice bran protein (RBP) has garnered increasing attention as a sustainable protein source due to its low cost and hypoallergenic properties. However, its complex composition and rigid structure negatively affect its emulsifying properties and interfacial behavior, thereby compromising the stability of emulsified gels. To elucidate the underlying mechanisms, RBP was subjected to heat treatment at 90 °C and pH 2.0 for 12 h to produce PF. The intermolecular structural changes and emulsion gel properties during fibril formation were investigated. As fibrils formed, the β-sheet structures increased significantly (p < 0.05), and protein flexibility improved by 79.46 % compared to native RBP. Particle size analysis, confocal laser scanning microscopy (LSCM), microscopic imaging, AP%, rheological properties, water-holding capacity (WHC), and texture analysis revealed that the emulsion gel prepared with PF exhibited smaller droplet sizes and a more uniform distribution. The AP% value was 77.23 % higher than that of the RBP-based emulsion gel. Rheological analysis showed that the PF-based emulsion gel had 129.17 % higher viscosity and 116.62 % higher storage modulus (G') compared to the RBP-based emulsion gel, indicating that PF effectively prevents droplet coalescence and enhances system stability. These findings suggest that engineering protein particles with fibrillar aggregation structures provides a novel strategy for developing stable plant protein-based emulsion gels.