From thermodenatured intermediate state aggregates to gel network formation: Thermodynamic and kinetic analysis of the reaction process of soybean protein fraction

: This study focused on protein fluorescence structure, particle size distribution, rheological changes, and the free energy of gelation reactions to investigate the thermal aggregation of β-conglycinin (7S) and globulin (11S) soybean proteins, as well as their thermodynamic and kinetic behavior during gelation induced by glucono-δ-lactone (GDL). The results indicate that the thermal denaturation of soybean protein 11S differs from that of 7S, exhibiting a variety of intermediate states and leading to the formation of multiple aggregates. When 7S and 11S coexist, their interactions lead to the formation of 11S-7S aggregates. Similar to aggregates formed by 11S or 7S alone, the gelation process of 11S-7S aggregates follows the time-temperature superposition principle. However, the gelation of 11S-7S aggregates consistently occurs earlier than that of mixtures of 11S and 7S aggregates. The 11S-7S aggregates exhibit a gelation pattern closer to that of 11S gels, where entropy plays a dominant role (ΔH*<-T av ΔS*), while the gelation of systems containing mixtures of 7S or 11S aggregates is primarily enthalpy-driven. These findings provide an energy-based explanation for the roles and mechanisms of different aggregates during the gelation of soybean protein systems, offering insights for regulating the processing quality of soy protein products.