ISOLATION OF GAMMA-GLUTAMYL PEPTIDES FROM COMTE CHEESE

Three gamma-glutamyl dipeptides (gamma-Glu-Phe, gamma-Glu-Tyr, and gam ma-Glu-Leu) were isolated from a water-soluble fraction of Comte chees e. Extraction of cheese with liquid CO2 led to a residue, which was th en extracted by citrate buffer. Purification was performed by gel perm eation and reverse-phase HPLC and identification by amino acid analysi s and mass spectrometry. Synthetic compounds corresponding to the iden tified dipeptides were tasted. The gamma-Glu-Tyr was sour and salty; g amma-Glu-Phe had a more intense and complex taste, which was brothy an d slightly sour, salty, and metallic. Taste thresholds of these dipept ides were evaluated, and their impact on cheese flavor is discussed.