Pasta filata process during Mozzarella cheese manufacturing was studied. System variables (SME, specific mechanical energy; TE, exit temperature) were defined and their relationships to operating conditions were investigated. The compositional, rheological and functional properties of cheeses manufactured under different conditions were analyzed and relationships between system variables and cheese properties were established. The cheese moisture content decreased as SME increased. A quadratic relation was established between cheese moisture content and TE, FDM (fat-in-dry-matter) and SME and FDM and TE. These relationships suggested that optimization of the cheese yield is possible by adjusting the pasta filata process operating parameters. Evaluation of microstructural features of the cheese samples further supported these conclusions. © 2004 Elsevier Ltd. All rights reserved.