Identification and flavor characterization of novel umami peptides from fermented wheat germ and their interactions with T1R1/T1R3 receptor

In this study, umami peptides were prepared and identified from fermented wheat germ, and their interactions with umami receptors T1R1/T1R3 were investigated. The optimal conditions for fermentation of wheat germ were yeast concentration at 5 g/100 mL, fermentation time at 48 h, fermentation pH at 4.0, and ratio of material to liquid at 1:14 (g/100 mL). Through ultrafiltration, the fraction of molecular weight less than 3 kDa exhibited stronger umami taste. A total of 99 peptides were identified by mass spectrometry and four umami peptides (EEL, DWK, TDEE, and VDSE) were screened based on molecular docking with T1R1/T1R3, where their binding amino acid sites were Gln52, Asp147, Arg151, Ser276, Ser148, and Arg307. These peptides were analyzed using sensory evaluation and electronic tongue analysis after synthesis. It revealed that the four peptides exhibited a strong umami aftertaste. Notably, the tripeptide DWK showed relatively stronger umami taste.