CONTRIBUTION OF CELL WALL-ASSOCIATED PROTEINASES OF LACTOCOCCUS TO THE PRIMARY PROTEOLYSIS OF BETA-CASEIN IN CHEDDAR CHEESE

Beta-Casein was hydrolyzed in vitro by cell wall-associated proteinases from Lactococcus lactis ssp. cremoris HP and L. lactis ssp. lactis JL 521 and JL 3601. Electrophoretograms of the hydrolyzates were compared with those of whole and water soluble extracts of Cheddar cheese made using these strains as starters. The peptides produced by hydrolysis of beta-casein in vitro were not detected in the 6 month-old cheese or water extracts therefrom. Inter-strain differences were observed in the electrophoretograms of the cheeses, water extracts and beta-casein hydrolyzates.The results of this study suggest that the cell wall-associated proteinases of the Lactococcus starters studied had little, if any, activity on intact beta-casein in Cheddar cheese; it is postulated that this is due to hydrophobic interactions in cheese of the susceptible regions of beta-casein.