Screening of Umami Peptides from Traditional Fermented Sea Bass Based on Microbial Metabolism and Their Inhibition on Bitterness

The aim of this study was to determine the interrelationship between umami peptides and microorganisms in traditional fermented sea bass and to explore the inhibitory effect of umami peptides on bitterness. Thirty-eight umami peptides were identified and predicted from traditional fermented sea bass using peptidomics combined with machine learning techniques, and the results of macrogenomic annotation indicated that a total of 51 microbial genera and 7 proteases were involved. Rhodococcus, Staphylococcus, Clostridium, Thiothrix, Pseudomonas and Achromobacter might play key roles in the formation of the flavor peptides in fermented sea bass. Molecular docking results showed that umami peptides EEEVVEEVE, DEEYPDL and DEEYPDLS could bind to the bitter taste receptor (TAS2R14), and their binding cavities were consistent. The interaction between the three peptides and TAS2R14 was mainly through hydrogen bonding, and the key binding sites of these peptides were SER265, SER69, SER65 and THR86. The electronic tongue results showed that all three umami peptides had a significant inhibitory effect on bitterness. This study provides a new idea to study the interaction between fish-derived umami peptides and bitterness.