Production of High-Quality Red Fruit Juices by Athermal Membrane Processes

Membrane-based processes are increasingly used to clarify and concentrate thermo-sensitive fruit juices and plant extracts as alternative to conventional processes. This work was aimed at evalu-ating the quality of red fruit juices clarified and concentrated by an integrated membrane process with special regard to the preservation of valuable compounds. A red fruit juice obtained from a blend of pomegranate, cactus pear and red orange juices of Sicilian origin was clarified by micro-filtration (MF) and then pre-concentrated up to 33 °Brix by nanofiltration (NF). The pre-concentrated juice was finally concentrated by osmotic distillation (OD) up to 50 and 60 °Brix. Samples of clarified, pre-concentrated and concentrated juice were analysed for their physi-co-chemical composition and in terms of antioxidant activity and inhibitory activity against alfa-amylase and lipase. Results clearly confirmed the assumption of a mild fruit juice processing method allowing to preserve the original nutritional and functional properties of the fresh juice. In particular, the OD retentate at 60 °Brix resulted the most active sample against pancreatic lipase and alfa-amylase inhibitory activity with IC50 values of 44.36 and 214.65 microg/mL, respectively.