Osmotic evaporation of red fruit juice and impact on quality and biological properties

Nowadays, the global market for non-alcoholic drinks, such as fruit juices, is continuously growing as consumers' preference is addressed towards healthier beverages. In particular, juices made from red fruit blends are highly requested products on the market due to their attractive taste, pleasing appearance and bioactive composition. Red fruits are known for accumulating a high amount of anthocyanins, water soluble pigments which are responsible for the color of these fruits. Their ingestion is helpful in fighting different pathologies, such as cancer, heart disease, and type 2 diabetes. Given the wide spectrum of healthy activities of these fruits, the interest of researchers has been addressed, in recent years, towards new methods capable of producing juices enriched in bioactive compounds with a high organoleptic profile. In this contest, this work was aimed at investigating, for the first time, a non-thermal concentration of a blend of cactus pear, pomegranate and blood orange juices for the production of a functional juice with improved antioxidant capacity and potentially able to counteract metabolic syndrome. The raw juice, with an initial total soluble solids content of about 13.8 °Brix, was previously clarified by ultrafiltration and then pre-concentrated by nanofiltration up to 33 °Brix. A concentration step up to 60 °Brix was carried out with a laboratory osmotic distillation (OD) unit using saturated calcium chloride brine as the extracting phase. The OD retentate preserved all the antioxidant compounds of the clarified juice and was the most active in all in vitro tests. Interesting, this fraction showed an antioxidant activity of 11.5 mM Trolox and inhibited ?-amylase and lipase with IC50 values of 214.6 and 44.4 microg/mL, respectively. The overall process allowed to produce a red fruit juice blend, rich in health-beneficial compounds with biological properties of interest for the production of functional foods and beverages.