Proteolysis of alpha s-casein as a marker of Grana Padano cheese ripening

Since casein proteolysis has a critical role in defining the typical characteristics of Grana Padano cheese, we evaluated the hydrolysis of ?s-casein during the ripening process. Thanks to the high specificity of the anti-?s(?s1 + ?s2)-casein monoclonal antibody and amino acid sequence determination, it was possible to identify three main ?s-casein-derived polypeptides in cheese: ?a, ?b, and ?c. Their production by the three enzymes most involved in cheese proteolysis (pepsin, chymosin, and plasmin) was evaluated by performing in vitro digestions. Data showed that ?a was released in cheese mainly by the chymosin attack, while ?b and ?c were due to the action of plasmin. A significant correlation between the abundance of some polypeptides and ripening process was shown.