Effect of added enzymes on the free amino acids and sensory characteristics in Ossau-Iraty cheese

A proteolytic and a lipolytic enzyme preparation were added (before clottin g) to the milk used to manufacture Ossau-Iraty-type ewes'-milk cheese. The free amino acids were analysed by reversed phase-HPLC and the sulphosalicyl ic acid-soluble N fraction was quantified by the trinitrobenzenesulphonic a cid method for use as indices of proteolysis during ripening. Sensory analy sis of the cheeses began after two months of ripening. The lipolytic enzyme preparation did not increase free amino acid levels, with even a slight de crease being recorded at the beginning of ripening. On the other hand, the proteolytic enzyme preparation caused an appreciable increase in proteolysi s, 20% higher than in the control batch after four months of ripening. The high level of exoproteolytic activity and concomitantly higher release of f ree amino acids related to sweet flavour, such as asparagine, serine, and p roline, may have masked the bitter flavours previously reported in the lite rature when proteolytic enzymes have been added. (C) 2000 Elsevier Science Ltd. All rights reserved.