Soy protein-based soft gels with tunable texture: Effects of enzymatic hydrolysis on their structure, rheological behavior, and nutritional properties.

Soy protein hydrolysates (SPHs) were obtained by using compound proteinases, and structure, gel characteristics and nutritional quality of soft gels constructed by them were systematically studied. The results showed that the molecular weight of SPI markedly decreased by enzymatic hydrolysis and the proportion of β-turn and random coil raised from 38.62% to 60.50%. This increased the gel network flexibility and its ability to retain water, contributing to a smoother and softer gel texture. Rheological analysis confirmed a weakened gel network formation capacity following enzymatic hydrolysis. Compared to the SPI gel, SPHs soft gels exhibited a significantly reduced hardness, complying with level 5 of the International Dysphagia Diet Standardisation Initiative (IDDSI). Meanwhile, the total amino acid content increased by 38.95%. Correlation analysis further confirmed that β-sheet unfolding served as a structural basis for soft gel formation. This work contributes to the innovation of plant-based diets tailored to swallowing difficulties.