Dynamic changes in nitrogenous compounds and taste-active substances during fermentation of tilapia-soybean...

This study investigated the dynamic changes in physicochemical properties, protein degradation, taste-active compounds, and overall flavor during the fermentation of tilapia-soybean dual-protein sufu (TSCS). During fermentation, moisture decreased during post-fermentation, NaCl increased after salt addition and then remained relatively stable, reducing sugars were continuously consumed, and acidity gradually increased. SDS-PAGE and nitrogenous compound analyses showed progressive protein degradation, accompanied by the accumulation of water-soluble proteins, polypeptides, amino acid nitrogen (AAN), free amino acids (FAAs), and taste-active nucleotides. Meanwhile, total volatile basic nitrogen (TVB-N) and biogenic amines remained within acceptable safety levels. FAAs increased markedly during post-fermentation, and umami- and sweet-tasting amino acids accounted for 40.21% of the final product, with Ala and Glu increasing by 2548.51% and 625.91%, respectively. Taste activity value (TAV) and equivalent umami concentration (EUC) further indicated that the synergistic interaction between umami amino acids and taste-active nucleotides was a major contributor to umami enhancement. E-nose, e-tongue, and sensory evaluation showed that TSCS developed from an early beany and bland profile to a mature flavor characterized by prominent umami, mellow taste, fine texture, and improved coordination. These results suggest that continuous dual-protein degradation and the accumulation of taste-active compounds jointly contributed to flavor development in TSCS, providing a basis for developing animal-plant dual-protein fermented foods.