Effects of Milk-Clotting Enzymes on Physical Properties of Mozzarella Cheese

Direct acid Mozzarella cheese was made in 6-L vats using calf chymosin, bovine pepsin, porcine pepsin, or Mucor miehei protease. Four cheeses were made with each enzyme. Stretch, melt, cook color (reflectance colorimeter), moisture, and pH were measured at 1, 7, 14, and 28 d. Correlation coefficients among these parameters were calculated, and the effects of choice of enzyme and storage time at 4'C on these parameters were evaluated by analysis of variance. Cook color was not affected by enzyme type and changed only slightly during storage. Melt was affected by choice of enzyme and increased significantly with time. During the 2 8 d ripening period, the melt of cheese made with calf chymosin increased the most. The smallest increase in melt was in cheese made with porcine pepsin. Stretch was significantly affected by enzyme and by storage time. Stretch decreased rapidly in all cheeses between d 1 and 7 and stabilized during the next 21 d. Cheese made with porcine pepsin had the greatest stretch, and cheese made with calf chymosin had the least stretch, between d 7 and 28. Melt increased, and stretch decreased, during storage of all cheeses. The type of milk-clotting enzyme used played a signjficant role in