Transglutaminase-catalyzed glycosylation of egg white peptides: Structural modulation and molecular mechanism of umami enhancement via T1R1/T1R3 interactions.

Egg white peptides (EWPs) face significant flavor challenges due to bitterness, limiting their high-value applications. This study prepared egg white glycopeptides (EWGP) through transglutaminase-catalyzed glycosylation to investigate their flavor enhancement effect. Egg white protein was hydrolyzed by neutral protease and covalently bound to glucosamine under the mediation of transglutaminase to obtain EWGP. Compared with original egg white peptide (EWP), EWGP contained more peptide bonds, increased intrinsic fluorescence intensity and improved surface hydrophobicity. Sensory evaluation and electronic tongue analysis demonstrated a 30 % increase in umami intensity and reduced bitterness in EWGP; with the addition of MSG, the thresholds of EWGP and EWP decreased from 1.00 and 1.22 mg/mL to 0.44 and 0.59 mg/mL, respectively. High umami and sweet amino acid content is the basis for the umami taste enhancement of EWGP. LC-MS/MS analysis showed that the glycosylation modification sites were specifically concentrated on the glutamine residues. Molecular docking showed that the glycopeptides formed a stable binding with the umami taste receptor T1R1/T1R3 through hydrogen bonding and hydrophobic forces, with Ala, Asn, Gln, Ser, Thr, and Tyr as key binding residues. In general, these findings establish TGase-mediated glycosylation as a green strategy for improving EWP flavor, advancing their potential as functional food ingredients.