New perspectives on the taste mechanisms of umami and bitter peptides in low-salt fermented fish sauce based on peptidomics, molecular docking and molecular dynamics†

Abstract

Umami and bitter peptides generated by microbial metabolism are essential to the taste of low-salt fish sauce. However, the uncertain taste mechanisms of peptides hinder the efficient identification of high-intensity taste peptides in fish sauce. Our study investigated the taste mechanisms of umami or bitter peptides from low-salt fish sauce fermented with Tetragenococcus halophilus. Herein, a total of 10 umami and 50 bitter peptides were identified from low-salt fish sauce by peptidomics, of which 6 umami peptides and 14 bitter peptides were primarily associated with Tetragenococcus, Lactobacillus, and Staphylococcus. Based on the low molecular docking energy with T1R1/T1R3 and TAS2R14, core umami (U6-RDEDLAP, U10-EPAEREFEFI, U18-PDEWEVAR) and bitter (B11-LAGICFV, B26-IGVNLTFF, B68-KTGPDPIPP) peptides were selected with hydrogen bonds and salt bridges as the primary forces, of which amino acid residues Arg, Glu, Asn, Lys, Gly, and Phe were mainly involved in ligand–receptor binding. Six novel taste peptides were further verified using the electronic tongue technique, among which U10 and B68 exhibited higher taste intensity, which might be related to their effective binding with the corresponding receptors. This study offers a theoretical foundation for screening novel high-intensity taste peptides in low-salt fish sauce, providing valuable insights into peptide-based taste enhancement based on microbial metabolism.