The effects of a commercial pregastric lipase enzyme (calf lipase) on the free fatty acid profile of Iranian UF (ultrafiltered)-Feta cheese during ripening period were investigated. Sensory evaluation and physico-chemical analysis of cheese samples were also performed. Commercial pregastric lipase (at the levels of 0, 2, 4 and 6 g 100 kg-1 of retentate) together with rennet was added to retentate. The main components (fat, total solids, salt, total nitrogen and water soluble nitrogen), pH value and free fatty acids were analyzed in cheese samples after 3, 20, 40 and 60 days of ripening. With an increase in lipase level and ripening period, the main components of cheese did not changed significantly but water soluble nitrogen increased during ripening period (P<0.05). With an increase in the pregastric lipase level, the percentages of C4:0-C8:0 fatty acids decreased significantly while that of C12:0-C18:0 and C18:1 increased. The percentages of C10:0, C18:2 and C18:3 did not change. With an increase in ripening period, the percentages of C4:0-C14:0 decreased while the percentages of C16:0, C18:0, C18:1 and C18:2 increased (p<0.05) and C18:3 percentage did not show any changes. Overall, sensory scores (appearance, flavour, body and texture and piquant taste) indicated that combination of 20 days with 6 g 100kg-1, 40 days with 4 g 100kg-1 and 60 days with 2 g 100kg-1 retentate were the best ripening conditions. The addition of lipase to cheese milk could be recommended for the acceleration of flavour development in UF-Feta cheese over a short ripening period.
