Investigation of umami peptides and taste mechanisms in Agrocybe aegerita: based on sensory evaluation and molecular docking techniques

In the present study, sensory orientation and instrumental analysis were employed to separate, purify, and identify umami peptides in Agrocybe aegerita hydrolysate. Using UPLC-ESI-Q-TOF MS, 11 potential umami peptides (EY, EG, EV, ENG, PEG, DEL, ECG, DDL, PEEL, EDCS and DGPL) were identified from the screened fractions. Moreover, sensory evaluation and E-tongue results showed that the identified umami peptides had umami attributes, within an umami threshold range of 0.0625-0.25 mg mL-1. In addition, DDL and DEL exhibited the highest umami flavor intensity. Molecular docking analysis further showed that 4 umami peptides (namely, EY, EG, ECG, and DGPL) entered the T1R1 cavity of the umami receptor. Additionally, 4 umami peptides (namely, EV, ENG, DEL, and EDCS) could be embedded in the binding pocket of the T1R3 cavity. Furthermore, 3 umami peptides (PEG, DDL, and PEEL) strongly interacted with T1R1/T1R3. Thus, the findings collectively indicated that the predominant interacting forces between umami peptide and umami receptor are hydrogen bonding and hydrophobic interactions. Finally, it was shown that the primary binding sites of T1R1 were residues Ser109, Gln52 and Ser148, while the primary binding sites of T1R3 were residues Ser172, Arg277 and Ala170. The study identified the umami peptides in A. aegerita for the first time, which provided more information for the umami research of A. aegerita and provided the theoretical basis for the further development and utilization of A. aegerita.