Preparation, identification and molecular characterization of umami peptides from skipjack tuna meat: Insights from sensory evaluation and molecular dynamics simulations

In this study, novel umami peptides were identified from skipjack tuna protein hydrolysates using enzymatic hydrolysis, purification, sensory evaluation, and molecular modeling. A hydrolysate with a high degree of hydrolysis was prepared using papain and flavor protease, and the most umami-active fraction was obtained through ultrafiltration and chromatographic separation. Fourteen peptides were identified, among which HAHA, QEYGGG, YD, DFDNA, DVPAE, EADH, and EYF showed lower umami thresholds than monosodium glutamate. Molecular docking and 100 ns molecular dynamics simulations revealed that DFDNA and DVPAE displayed low RMSD values, while key residues in the T1R1 and T1R3 subunits remained structurally stable. High-affinity peptides formed persistent hydrogen bonds and π interactions with the receptor complex. Short peptide length and the presence of acidic and aromatic residues were crucial for receptor recognition. Overall, these results clarify the molecular basis of umami perception and provide practical guidance for designing natural peptide-based flavor enhancers for applications.