Detection of plasmin-mediated beta-casein hydrolysis in milk and cheese through immunochemical techniques

In this article recent advances in development of selective immunochemical reagents to monitor plasmin-mediated beta-casein hydrolysis are reported and briefly discussed. The attention was mainly focused on antipeptide antibodies specifically recognizing significant peptides derived from beta-casein plasmin hydrolysis in milk and cheese. Analytical potentialities of the polyclonal antibodies raised against native or synthetic peptides were evaluated and possible applications of the antipeptide antibodies preparations to the quality control of dairy products were suggested. Progression of plasmin-mediated hydrolysis of beta-casein occurring in Parmigiano Reggiano cheese during ripening was easily followed by immunoblotting using antipeptide antibodies raised against the five amino acid residue peptide reproducing the N terminus of gamma2- casein. The release of the 1-28 phosphopeptide from beta-casein was monitored in maturing cheese by competitive ELISA using antipeptide antibodies raised against RP-HPLC purified 1-28 phosphopeptide from bovine beta-casein. Finally, a preparation of antipeptide antibodies, raised against a synthetic peptide carrying a properly chosen bovine beta-casein sequence, was able to reveal selectively bovine and water buffalo beta-casein and their derived gamma2-and gamma3-caseins but not the ovine and caprine counterparts, so that it is a suitable reagent for ELISA detection of bovine casein in adultered ovine and caprine cheese samples.