Isolation of γ-Glutamyl Peptides from Comté Cheese

Three γ-glutamyl dipeptides (γ-Glu-Phe, γ-Glu-Tyr, and γ-Glu-Leu) were isolated from a water-soluble fraction of Comté cheese. Extraction of cheese with liquid CO2 led to a residue, which was then extracted by citrate buffer. Purification was performed by gel permeation and reverse-phase HPLC and identification by amino acid analysis and mass Spectrometry. Synthetic compounds corresponding to the identified dipeptides were tasted. The γ-Glu-Tyr was sour and salty; γ-Glu-Phe had a more intense and complex taste, which was brothy and slightly sour, salty, and metallic. Taste thresholds of these dipeptides were evaluated, and their impact on cheese flavor is discussed.