Proteolysis of α_s-Casein as a Marker of Grana Padano Cheese Ripening

摘要

Since casein proteolysis has a critical role in defining the typical characteristics of Grana Padano cheese, we evaluated the hydrolysis of αcr.-casein during the ripen- ing process. Thanks to the high specificity of the anti- α_s,(α_s1 + α_s2)-casein monoclonal antibody and amino acid sequence determination, it was possible to identify three main cr.-casein-derived polypeptides in cheese: α_a, α_b, and α_c. Their production by the three enzymes most involved in cheese proteolysis (pepsin, chymosin, and plasmin) was evaluated by performing in vitro di- gestions. Data showed that α_a was released in cheese mainly by the chymosin attack, while α_band α_c were due to the action of plasmin. A significant correlation between the abundance of some polypeptides and ripen- ing process was shown.