Effect of Proteolytic Activity of Streptococcus cremoris on Cottage Cheese Yields

Using only a proteinase-negative variant of Streptococcus cremoris UC3t0 to manufacture cottage cheese increased theoretical yields by 2.26% compared wth the proteinase-positive parent.Yield differences between positive and negative variants were strain dependent and not detected with variants of UC73 and UC97.Growth of proteinase-negative variants in bulk culture required pH control and addition of sufficient nitrogenous stimulant to provide carry-over activity into the cheese milk.Cultures developed normally when the bulk medium contained 5% of a blend of yeast extract and casein hydrolyzate.Proteinase-negative culture successfully completed acidification of cottage cheese milk after direct acidification to pH 5.2 with phosphoric acid.Lactic culture strain selection is suggested for maximizing product yields with proteinasenegative cultures.