This study reports the effect of psychrotrophs in raw milk on the quality of Mozzarella cheese. Physical, chemical, sensorial and textural characteristics were evaluated, and the indices of lipolysis and proteolysis were assessed. The highest population (7 log cfu/mL vs. 3 log cfu/mL) was associated with a decrease in yield and in primary proteolysis index, higher acidity and free fatty acid index and concentration. Short-and medium-chain free fatty acids increased in all cheeses during storage, being higher in those produced with milk containing a high population of psychrotrophics. No sensory differences between the cheeses were observed.