Effects of salt ions and pH on deamidated soybean protein hydrogels formation: Molecular structure, thermal aggregation and network

The aim of this study was to explore the effects of environmental factors (salt ions and pH) on the thermal gelation process of deamidated soy protein isolate (DSPI). The results indicated that with increasing salt ion concentration, DSPI assembled into larger aggregates, which were more prone to aggregation in thermal reactions, ultimately forming a gel network with higher viscoelasticity. The strength enhancement of ion-induced gel networks followed the order from highest to lowest: Ca²⁺ > Mg²⁺ > Na⁺. Regarding pH, as the pH value shifted from 11 to 3, the structure of DSPI transitioned from disorder to order, which promoted protein aggregation, thereby enhancing the strength of the gel network. This work elucidates how environmental factors regulate the gel properties of DSPI through molecular structure, thermal aggregation, and gel networks, thereby laying the foundation for expanding the industrial applications of DSPI.