Mechanism for the Differential Taste-Enhancing Effect of the Kokumi Peptide γ-Glutamyl-Valine

γ-Glutamyl-valine (γ-Glu-Val) has variable taste characteristics, and its aqueous solution presents an astringent taste, but can enhance the basic taste intensity and impart a kokumi taste to foods such as cheese, chicken soup and soy sauce. However, there are few mechanistic studies on the taste characteristics of γ-Glu-Val especially its differential taste-enhancing effects. In this study, the mechanism for the differential enhancing effects of γ-Glu-Val on basic tastes was elucidated via molecular modeling approaches and sensory evaluation. The results showed that γ-Glu-Val could enhance the intensity of basic tastes (umami, sweet, salty and sour), especially umami taste. Molecular modeling showed γ-Glu-Val had a certain affinity for basic taste receptors (T1R1, T1R2, and T1R3). The highest binding affinity and free energy to the umami taste receptor T1R1 were observed as well as the lowest binding affinity and free energy to the sweet taste receptor T1R2, suggesting that umami taste was more strongly enhanced than sweet taste by γ-Glu-Val. Molecular dynamics results showed that γ-Glu-Val could interact with the amino acid residues in the umami taste receptor T1R1 (Phe-274, Ser-275, Ser-300, Trp-303, Ala-147 and Ala-170) through hydrogen and hydrophobic bonds in the presence of monosodium glutamate (MSG), activating the umami taste receptor for umami taste enhancement. The results of this study will provide theoretical support for further understanding the mechanism for the taste-enhancing effect of γ-Glu-Val and other small molecule substances.