Ion-exchange purification, nano-HPLC-MS/MS identification and molecular dynamics simulation of novel umami peptides from fermented grain wine (Huangjiu)

Huangjiu is a traditional Chinese fermented rice wine with abundant peptides, but the umami peptides are little known due to the wine's complex matrix. Herein, the target umami fraction was enriched with sensory-guided separation coupled with ultrafiltration, ion-exchange, and gel chromatography purification. A total of 1901 peptides were identified from gel F1 fraction with nano-HPLC-MS/MS. Eight novel umami peptides DWDPHGL, VPEPEPH, LTPEPEH, GANQLDPR, FREE, LDFR, QEGW, and RDH were filtered by virtual screening and sensory evaluation. They exhibited thermal stability at 373.15 K and the taste thresholds in water were between 0.29 and 0.65 mmol/L. Among them, RDH was crucial, due to a relatively high dose over threshold (DoT) factor (1.12). Molecular docking results showed that residues ASP147, SER148, ARG151, TYR220, SER276, and ALA302 contributed most to the interaction of peptide and T1R1. Moreover, molecular dynamics simulation and weak interaction analysis suggested the important role of intramolecular forces in peptide thermal stability.