Revealing the Influence of 7S Globulin Hydrolyzates with Varying Hydrolysis Degrees on the Thermoresponsive Behavior of Methylcellulose in Aqueous Solutions

This study employed soy 7S globulin and its enzymatic hydrolyzates as model systems to elucidate how protein size, surface hydrophobicity, and secondary structure affect the thermo-induced network formation of methylcellulose (MC). Protein hydrolysis decreased the protein size, reduced hydrophobicity, and triggered partial rearrangement of its secondary structure. Atomic force microscopy (AFM), confocal laser scanning microscopy (CLSM), and rheology showed that, at high temperatures, unhydrolyzed 7S globulin (P0) promoted MC fibril interchain association through hydrophobic interactions, creating a strong yet heterogeneous network. In contrast, higher hydrolysis levels (P1–P3) produced smaller, more uniformly distributed protein aggregates and thinner, more interconnected fibrils but a mechanically weaker network. Overall, enzymatic hydrolysis can finely regulate the morphology and mechanical properties of protein–MC networks at high temperatures, providing insights for designing protein–polysaccharide composite systems and optimizing their performance in food and material applications.