Physical chemical properties and antioxidant capacities of grapefruit juice (Citrus paradisi) extracted from two different varieties

This study was undertaken to determine the physical and chemical properties and the antioxidant compounds of grapefruits (Marsh and Star Ruby varieties) grown in South Italy. Flavanones (narirutin, naringin, hesperidin, neohesperidin, and poncirin), flavones (rutin) and aglycones (quercetin, naringenin and hesperetin) have been identified in the grapefruit juices examined. The concentration of total flavonoids ranged between 310 and 390 mg L-1 juice. Naringin was found to be the major flavonoid followed by narirutin and poncirin. Their concentrations ranged from 198.10 to 287.97; from 37.07 to 38.87 and from 14.22 to 17.32 mg L-1 juice, respectively. Antioxidant activity (DPPH) ranged from 35.25 (Star Ruby) to 46.08% inhibition (Marsh).