Physico-chemical stability of blood orange juice during frozen storage

ABSTRACTBlood orange juice from Citrus sinensis (L) Osbek cv Moro was compared to a concentrated blood orange juice and both juices were studied during frozen storage at −20 °C. Analyses were conducted on pH (3.33–3.81) and titratable acidity as citric acid (11.14–13.16 g/L). The formol number decreased in both blood orange juice and concentrated blood orange juice during frozen storage, while vitamin C showed a very slight decrease. Scavenging abilities of the juices for the DPPH∙ radical ranged from 53.39% to 42.55% in blood orange juice and from 39.16% to 33.75% in concentrated blood orange juice during frozen storage. Although anthocyanins showed a diminution during storage in both the concentrated and non-concentrated blood orange juice, they were always higher in the non-concentrated juice fruit. Four phenolic acids were detected: gallic, chlorogenic (the highest quantity, 13–27 mg/L), caffeic and ferulic, the latter showed the lowest content. Ten flavonoids were identified, 2 flavonols (rutin and q...