"Quesucos de Liebana" cheese from cow's milk: biochemical changes during ripening

The changes in chemical composition, main physico-chemical parameters. clas sical nitrogen fractions, caseins and their degradation products. and some fat characteristics were studied during the ripening process of 10 batches of Quesucos de Liebana cheese. a traditional variety made in the north of S pain. The values of the different compositional and physico-chemical parame ters at the end of the ripening did not differ significantly from those fou nd in other cow's milk cheeses elaborated with similar technology. The pres ence of residual lactose at the end of the ripening process is outstanding. The total soluble nitrogen increased by a factor of 2 at the end of the ri pening compared to the values shown at the beginning. However, non-protein nitrogen increased very little. The final values of the different nitrogen fractions show that this cheese undergoes a proteolysis moderate in extensi on but not very intense and that the rennet is the main agent of the proteo lysis produced during ripening. Using PAGE techniques, it was possible to s how that, throughout ripening, 56% of alpha(s)-casein and 11% of beta-casei n turned out to be degraded. The TEA number and acidity index of the fat va lues show that the processes of lipolysis and fat autooxidation during the ripening of this cheese are not very intense. (C) 2000 Elsevier Science Ltd . All rights reserved.