Mechanism of ultrasonic-alkali-thermal modification for enhancing the emulsifying properties of rice protein and its stability in high-internal-phase emulsions
Lijie Zhu, Haiqiang Liao, Kun Zhuang, Shangyuan Sang, Lei Chen, Xianhui Chang, Qi Zhang, Qingyun Lv, Xiuying Liu, Xinqi Liu, Wenping Ding
Abstract
• Ultrasonic-alkali-thermal enhanced the surface hydrophobicity of rice protein. • Assess interface adsorption by measuring interfacial tension and contact angle. • Ultrasonic-alkali-thermal treated rice protein decreased emulsion particle size. • Ultrasonic-alkali-thermal enhanced the ability of rice protein to stabilize emulsion. Rice protein, as a hypoallergenic plant protein, faces limitations in food industry applications due to the poor emulsification of its native form. In this study, rice protein was subjected to ultrasonic, alkali-thermal, and combined ultrasonic-alkali-thermal treatments. Experimental results revealed that the ultrasonic-alkali-thermal combined treatment significantly reduced the particle size to 129.67 nm. Structural analysis showed an increase in random coil content within the secondary structure, indicating a transition from ordered to disordered conformation. Contact angle measurements demonstrated improved intermediate wettability of the modified protein. The high-internal-phase emulsion prepared with ultrasonic-alkali-thermal treated rice protein exhibited enhanced stability, with the Turbiscan Stability Index as low as 0.39, reduced emulsion particle size (14.17 μm), and elevated storage moduli. These findings collectively suggest that the ultrasonic-alkali-thermal treatment is an effective strategy for enhancing the emulsifying properties of rice protein.