Influence of Screw Speeds of the Mixer at Low Temperature on Characteristics of Mozzarella Cheese

We determined the impact of screw speeds of the mixer on chemical composition, proteolysis, and functional properties of low moisture part-skim Mozzarella cheese during storage. Three vats of cheese were made in 1 d using three different mixer screw speeds (5, 12, and 19 rpm). The mean temperatures of the cheese during stretching at different screw speeds were 55.5, 52.5, and 51.5°C, respectively. Cheese making was replicated on each of 3 d using a randomized block design. The high screw speed caused tearing of the cheese curd in the screws before the curd temperature had increased sufficiently to soften the curd and permit deformation and stretching under the shear force of the screws. The highest mixer screw speed produced cheeses with a significantly lower moisture content, lower FDB, and higher protein content, yielding cheese with a firmer texture. Proteolysis was not significantly influenced by screw speed, but lower mixer screw speeds resulted in a greater release of free oil from the cheese initially and throughout refrigerated storage. Control of temperature and mechanical treatment of the cheese during stretching could allow cheese makers to improve control of the composition and functionality of Mozzarella cheese.