Isolation and identification of novel umami-enhancing peptides from fermented soybean meal hydrolysate by consecutive chromatography and UPLC–ESI–QTOF–MS/MS

In this study, the rich enzyme system of Aspergillus oryzae was utilized to hydrolyze the fermented soybean meal, producing a hydrolysate with enhanced flavor characteristics. Ultrafiltration, XAD-16 resin, and gel chromatography were used in conjunction with sensory-guided separation to systematically isolate umami-enhancing peptides fractions from fermented soybean meal hydrolysate. Four peptides were identified as ME, EL, EA and EV through sensory evaluation and UPLC-ESI-QTOF-MS/MS. These peptides were synthesized using solid-phase synthesis and the taste profiles were further validated through sensory evaluation and taste intensity tests. All peptides were perceived as umami in two solutions, with umami-enhancing thresholds from 15 to 34.75 mg/L in the I + G solution and 21.80–55 mg/L in the MSG solution, respectively. The dose–response test revealed that ME, EL and EA exhibited stronger umami-enhancing intensity effects, while EV were more significant in MSG solution. Receptor-peptide docking results confirmed that the umami taste of four peptides may be perceived mainly through the formation of hydrogen bonds with the hydrophilic amino acids of T1R1/T1R3, involving key receptor residues Arg277, Ser276, Asp147, etc. This study provided a theoretical basis for the development and application of umami-enhancing peptides from fermented soybean meal hydrolysates.