BETA-CASOMORPHINS - ANALYSIS IN CHEESE AND SUSCEPTIBILITY TO PROTEOLYTIC-ENZYMES FROM LACTOCOCCUS-LACTIS SSP CREMORIS

Commercial cheese products were surveyed for beta-casomorphin peptides . Two extraction methods were compared: 1) water and 2) chloroform and methanol. Peptide profiles were determined using reverse-phase HPLC a nd multiple wavelength detection. beta-Casomorphin standards were used for comparison with cheese peptide profiles. Results indicated that p eptides were present in cheeses with HPLC elution times that were simi lar to those for beta-casomorphins. However, comparison of absorbancie s of the peaks at multiple wavelengths did not indicate peptides simil ar to beta-casomorphins. Therefore, beta-casomorphins were absent, or concentrations were below the HPLC detection threshold for beta-casomo rphin of 2 mu g/ml of cheese extract. The susceptibility of beta-casom orphins to the proteolytic system of a commercial strain of Lactococcu s lactis ssp. cremoris was investigated. beta-Casomorphin standards we re incubated at 4 degrees C with bacterial cell lysate at pH 5.0, 5.2, 5.4, and 5.7. Salt concentrations varied among 0, 1.5, and 5%. The co ncentration of added beta-casomorphins and the degradation products we re monitored over 15 wk using HPLC. Enzymatic degradation of beta-caso morphins was influenced by the combination of pH and salt concentratio ns at cheese ripening temperatures. Therefore, if formed in cheese, be ta-casomorphins may be degraded under conditions common for Cheddar ch eese.