Evolution of free amino acid content during ripening of Mahon cheese

Evolution of free amino acids (FAA) during ripening (10-300 days) of five batches of Mahon cheese was studied; three batches were made from raw milk and two from pasteurized milk. Major FAA were GLU, VAL, LEU, LYS and PHE (43-67% of total FAA). Relative THR, SER, GLU and GLY contents significantly increased during ripening whereas LEU, PHE and ORN decreased. GLU, ILE, SER, THR, GLY and PHE varied during ripening according to a zero order reaction (r(2) > 0.99). Principal component analysis showed that the first principal component could be considered representative of the ripening time. The most ripened cheeses showed high GLU, GLY, SER and THR contents and the less ripened cheeses presented high ORN, LEU, PHE and ALA contents. The second component distinguished between cheeses made with pasteurized milk (with high ASN and GLN contents) and raw milk. Indigenous microflora of raw milk showed a strong influence on the proteolytic activity in Mahon cheese. (C) 1997 Elsevier Science Ltd.