MONITORING CHEDDAR CHEESE RIPENING BY CHEMICAL INDEXES OF PROTEOLYSIS.3. IDENTIFICATION OF SEVERAL HIGH-MOLECULAR-MASS PEPTIDES

Two Cheddar cheeses from two different production plants were ripened over 24 weeks at 10-degrees-C and then analysed for peptides soluble i n citrate buffer at pH 4.6 by reversed-phase (RP)-HPLC. Thirteen pepti des with a chain length of between 35 and 65 amino acid residues and m olecular masses between 3800 and 7400 were isolated and assigned to th e corresponding amino acid sequences of the casein fractions via Edman degradation and amino acid composition. All peptides were fragments o f the region K29-S96 of beta-caseine A1 and A2, and eleven of them had M93 as the C-terminal. The amounts and proportions of these peptides varied differently during ripening of the two cheeses, so they may be suitable markers for characterizing the stage of ripening.