Health-promoting properties of red fruit juice concentrated by non-thermal membrane process

The consumption of red fruits is growing worldwide not only for their nutritive value, flavor, attractive taste, but also due to their well-known health-promoting properties (as dietary sources of bioactive compounds) showing a protective effect against many chronic diseases (cancer, heart disease, and type 2 diabetes). At the same time, among consumers, there is a growing demand, for safe and natural red fruit juices, produced with sustainable or ecological technologies capable to preserve the bioactive compounds (especially anthocyanins) susceptible to degradation at high temperature, exposure to oxygen and operations such as concentration. In light of these trends, this work aims at investigating, for the first time, the non-thermal concentration of a blend of pomegranate, prickly pear and blood orange juices of Sicily origin for the production of a concentrated red juice with enhanced antioxidant capacity and potentially able to counteract obesity and type 2 diabetes. The juice blend (65% blood orange, 25% pomegranate, 10% prickly pear) was clarified by microfiltration (MF), then pre-concentrated by nanofiltration (NF) up to 33 °Brix and finally concentrated up to 60 °Brix by osmotic distillation (OD). Experimental results showed that the content of bioactive compounds as well as the antioxidant activity of the original juice was very well-preserved in the concentrated juice independently of the concentration factor. The OD retentate at 60 °Brix showed an antioxidant activity of 11.5 mM of Trolox and a concentration of polyphenols, anthocyanins and flavonoids of 1363.92 mg GAE/L, 312.61 ppm and 400 ppm, respectively. It resulted also the most active sample against pancreatic lipase and ?-amylase inhibitory activity with IC50 values of 44.36 ± 0.85 and 214.65 ± 2.03 ?g/mL, respectively. The concentrated blend, with enhanced health-promoting properties, offers interesting perspectives for developing phytochemical functional products (anti-cholesterol, antidiabetic, antiviral, antimicrobial, antiinflammatory, antihypertensive products) and dietary supplements.