EVOLUTION OF FREE AMINO-ACIDS DURING IDIAZABAL CHEESE RIPENING

As a contribution to knowledge of ripening ewe's cheese, the evolution of free amino acids was studied over a year of the ripening period by reversed phase high performance liquid chromatography (RP-HPLC). Total free amino acid content during Idiazabal cheese ripening varied between 140 mg/100 g dry matter the first day and 1500 mg/100 g dry matter at one year. The major amino acids were: glutamic acid, leucine, valine, phenylalanine, lysine and alanine which approximately accounted for 50% of the total free amino acid content, probably indicating the preferential cleavage of peptide bonds by the proteolytic agents in the cheese. Non-protein amino acids such as ornithine, citrulline or gamma-aminobutyric acid were also found in proportions near to 9% of the total free amino acids. Amino acids such as arginine, which is responsible for unpleasant tastes, or gamma-aminobutyric acid, which is usually detected in low quality cheese, are present in very low concentrations in Idiazabal cheese.