The level of proteolysis during refrigerated storage of Mozzarella cheese can have an effect on functionality including stretching and melting characteristics. Proteolysis in Mozzarella cheese could be influenced by several manufacturing parameters including: salting pH (SP), salting rate (SR), and stretching temperature (ST). The objective of this study was to evaluate the effects of SP, SR and ST on Mozzarella cheese proteolysis during storage. Thirty-two batches of Mozzarella cheese were manufactured using a partial split plot design that included a range of protein-to-fat ratios (1 to 4.5) in the main plot. In the sub plot, 2 salting pH (5.2 and 5.6), 2 salting rates (1.5% and 2.2%), and 2 stretching temperatures (65°C and 85°C) were used. After manufacture Mozzarella cheese was vacuum packed and stored at 4°C for 28 d. After storage, proteolysis was determined by measuring the soluble protein at pH 4.6 as a percentage of total protein content. Proteolysis and composition data were analyzed using simple linear regression analysis to establish potential relationships among the cheese compositions (moisture, fat, and protein), SP, SR, ST and proteolysis. Linear regression analysis indicated that proteolysis was primarily influenced by ST and cheese manufactured with the high ST always resulting in less proteolysis as compared with the low ST. Subsequently the GLM procedure of SAS was utilized to conduct an ANOVA. The results determined that milk fat and protein content, and ST had a significant effect (P < 0.05) on cheese proteolysis, whereas no significant effects were observed for SP and SR. These results demonstrate that in this study milk composition and stretching temperature were the primary factors influencing proteolysis of mozzarella cheese. This information can be used by cheese manufacturers to control the level of proteolysis in Mozzarella cheese.