Effects of ultrasonic pretreatment on the fibrillation of soy protein isolate, β‑conglycinin, and glycinin: Kinetics, structure, and functional properties

This study systematically investigated the effects of ultrasonic pretreatment on the fibrillation behavior of soy protein isolate (SPI), β-conglycinin (7S) and glycinin (11S). A multi-analytical approach combining Thioflavin T fluorescence spectroscopy, SDS-PAGE, dynamic light scattering, zeta potential measurement, and spectroscopic analyses was employed to monitor fibrillation kinetics and structural modifications. Ultrasonication significantly accelerated the fibrillation process by enhancing nucleation, increasing the apparent rate constant of 7S by 44% and that of SPI by 67%. SDS-PAGE analysis indicated that ultrasound treatment promoted protein degradation, generating a greater number of low-molecular-weight peptides, which may have facilitated fibril nucleation. Ultrasound treatment reduced protein particle size, increased surface charge, and promoted conformational transitions toward β-sheet-rich structures, with U-7SN showing a 20.8% rise in β-sheet content. These structural changes were correlated with enhanced functional properties, including improved solubility, emulsifying activity, and viscosity. The findings demonstrated that ultrasound promoted fibrillation by enhancing hydrophobic interactions and the formation of β-sheet structures, offering a theoretical basis for tailoring plant protein nanofibrils with targeted functionalities for food and material applications.