Fast Isoelectric Focusing and Antipeptide Antibodies for Detecting Bovine Casein in Adulterated Water Buffalo Milk and Derived Mozzarella Cheese

Plasmin hydrolysis of water buffalo casein (CN) can liberate a peptide comigrating with bovine gamma2-CN. Occurrence of this peptide may lead to false-positive detection of cows’ milk for a genuine water buffalo cheese, when it is analysed applying a fast version of the European official method for detecting bovine casein in water buffalo cheese. After isoelectric focusing of CN plasminolysates, performed according to the official method, immunoblot analysis with anti-peptide antibodies was assayed to distinguish between gamma2-CN and the interfering bovine gamma2-CN-like peptide. Small, synthetic peptides containing partial sequences of bovinegamma2-CN were used as immunogens for anti-peptide antibodies raised in rabbits. The antibody preparation directed toward the synthetic peptide containing the first five amino acid residues of gamma2-CN cross-reacted with native and in vitro generated gamma2-CN from bovine and water buffalo CN, but it did not recognize bovine gamma2-CN-like band in the electrophoretic profile of pure water buffalo CN.