Free amino acids as indices of Mahon cheese ripening

We studied the pattern of release of free amino acids during ripening of Mahon cheese made from pasteurized milk or from raw milk. Samples corresponded to fresh (30 d), medium-cured (120 d), and cured (210 d). Cheeses were obtained from commercial factories. Free amino acids were determined by HPLC. Amino acids can be grouped according to their pattern of release during ripening through cluster analysis. Linear regression analysis was made of selected amino acid concentrations versus ripening time. Amino acids with a high correlation coefficient were suitable as an index of ripening. Lysine, threonine, valine, methionine, glutamate, and phenylalanine were considered for cheese made from pasteurized milk, and alanine, valine, leucine, glutamate, isoleucine, and lysine were considered for cheese made from raw milk. Stepwise discriminant analysis of the data enabled us to configure a classification system for cheese samples. Discriminant functions were applied to the chromatogram of amino acids of an unknown sample to enable its classification as one of the cheese samples studied. Classification of all the cheeses according to type and age was achieved.