EFFECTS OF PROTEOLYTIC ACTIVITY OF THERMOLACTIC CULTURES ON PHYSICAL-PROPERTIES OF MOZZARELLA CHEESE

The effect of proteolytic activity over time on physical parameters of Mozzarella cheese was examined. The proteolytic activity of a collection of commercial strains of Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus salivarius ssp. thermophilus was determined by the o-phthaldialdehyde test. Characteristics of trial vats (6 L) of Mozzarella cheese manufactured using single or paired strains either high or deficient in proteolytic activity were compared with Mozzarella cheese manufactured by direct acidification. Cheeses were analyzed for cook color by a reflectance colorimeter, melt by a tube test, and stretch by a helical viscometer at 1, 7, 14, and 28 d of storage at 4-degrees-C. Cheese made with single strains of proteinase-deficient L. delbrueckii ssp. bulgaricus exhibited less browing, greater melting, and less stretch than cheese made with single proteolytic strains. Cheese made with pairs of proteinase-deficient strains of L. delbrueckii ssp. bulgaricus and S. salivarius ssp. thermophilus showed less browning and melting, but no difference in stretch compared with cheese made with proteinase-positive pairs. All cultured cheese had greater stretch, melt, and more browning than direct acid cheese after 1 d of storage. Cheese made with single strains of L. delbrueckii ssp. bulgaricus had greater stretch and less melt than cheese made with paired strains.