Study of the biochemical changes during ripening of Ahumado de Aliva cheese: a Spanish traditional variety

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 of ten batches of Ahum ado de Aliva cheese, a traditional variety made in the north of Spain. The values of the different compositional and physico-chemical parameters at th e end of the ripening did not differ significantly from those found in othe r cows' milk cheeses elaborated by similar technology. The low pH values ar e outstanding. The presence of residual lactose at the end of ripening is a lso relevant. Total soluble nitrogen and nonprotein nitrogen increased very little during ripening. The evolution of the values of the different nitro gen fractions show that this cheese undergoes very little proteolysis and t hat the rennet is the main proteolytic agent. Using PAGE, it was possible t o show that, throughout ripening, only 22% of alpha (s)-casein and 9% of be ta -casein were degraded. The TBA value indicated that the fat of Ahumado d e Aliva cheese does not undergo noticeable autooxidation during ripening. T he acidity index of the fat also indicated that this cheese underwent littl e lipolysis during ripening. (C) 2001 Elsevier Science Ltd. All rights rese rved.