Proteolysis of β-casein as a marker of Grana Padano cheese ripening

Abstract

Proteolysis has a critical role in defining the typical organoleptic characteristics of Grana Padano, a wellknown Italian cheese. During the ripening process, hydrolysis of β-casein produces different fragments, the most abundant and widely studied of which are γ-caseins, three polypeptides containing the HOOC-terminal portion of β-casein. By sodium dodecyl sulfate-PAGE and a specific anti-β-casein monoclonal antibody, two β-casein-derived bands were identified in Grana Padano cheese: βa and βb. Thanks to the identification of the amino acid sequences, it was shown that: a) βa contains γ1-casein [β-casein (29-209)] and the correlated peptide [β-casein (30-209)]; b) βb contains γ2-casein [β-casein (106-209)] and γ3-casein [β-casein (108-209)]. The production of βa and βb by the three enzymes most involved in cheese proteolysis (pepsin, chymosin, and plasmin) was evaluated by performing in vitro digestions. A significant correlation between abundance of some polypeptides and ripening process was shown. © 2001 Elsevier Science Ltd. All rights reserved.