Proteolysis of beta-casein as a marker of Grana Padano cheese ripening
2001
Gaiaschi, A. | Beretta, B. | Poiesi, C. | Conti, A. | Giuffrida, M.G. | Galli, C.L. | Restani, P.
Proteolysis has a critical role in defining the typical organoleptic characteristics of Grana Padano, a well-known Italian cheese. During the ripening process, hydrolysis of beta-casein produces different fragments, the most abundant and widely studied of which are gamma-caseins, three polypeptides containing the HOOC-terminal portion of beta-casein. By sodium dodecyl sulfate-PAGE and a specific anti-beta-casein monoclonal antibody, two beta-casein-derived bands were identified in Grana Padano cheese: beta(a) and beta(b). Thanks to the identification of the amino acid sequences, it was shown that: a) beta(a) contains gamma1-casein [beta-casein (29-209)] and the correlated peptide [beta-casein (30-209)]; b) beta(b) contains gamma2-casein [beta-casein (106-209)] and gamma3-casein [beta-casein (108-209)]. The production of beta(a) and beta(b) 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.
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