Effect of ewe's-milk pasteurization on the free amino acids in Idiazabal cheese

This study compared the use of raw and pasteurized milk in the manufacture of Idiazabal ewe's-milk cheese. Two indigenous starters, A and B were teste d in an attempt to find a starter culture potentially capable of developing the typical characteristics of Idiazabal cheese traditionally made from ra w milk while using pasteurized milk. The nitrogen fractions and free amino acids were analysed over the ripening period. Pasteurization caused a consi derable decrease in amino acid release in the cheese during ripening as ref lected by the levels of non-protein-nitrogen and total free amino acids wit h starter A, but not when starter B was used. Multivariate analysis confirm ed increases in asparagine, serine, and taurine and decreases in aspartic a cid and glycine with pasteurization, irrespective of the starter used. The changes recorded in the levels of certain amino acids may be directly or in directly responsible for the atypical sensory characteristics of the cheese s. Pasteurization of the milk for the manufacture of Idiazabal cheese is no t recommended with either of the two starters tested. (C) 1999 Elsevier Sci ence Ltd. All rights reserved.