Characterization of antioxidant compounds i n Jaffa sweeties and white grapefruits

Abstract

Antioxidant compounds and the antioxidative activities of new Israeli citrus fruit sweetie [(Oroblanco, pummelo-grapefruit hybrid (Citrus grandisx C. paradisi)J were compared with the better-known white grapefruit. Total and free phenols were determined with the Folin-Cioca l teu reagent, phenolic acids (free, esters and glycosides) by HPLC analysis and anthocyanins spectro­ photometrically. The antioxidant activities were estimated with two scavenging radicals: 2, 2'-azinobis (3-ethylbenzothiazoline-6- stllfonate)- (A BTS) and nitric oxide (NO). Free radical scavenging properties of sweetie and grapefruit were evaluated by -carotene bl eaching W-carotene). The results of kinetic reactions showed that both fruits differed in their capacities to quench these radicals and sweetie showed more antioxidative <JCtivity than grapefruit. Trans-hydroxycinnamic acids (cafTeic, p-coumaric, ferulic, and sinapic) were more abundant in grapefruits than in sweeties. High correlat i on was observed between antioxidative activities and phenols (R 2 = 0.94). Both fruits have high concentrations of natural antioxidants with high antioxicla tive activities. Phenol con­ tent and the antioxidative potential are significantly higher in sweetie than in grapefruit. The higher antioxidant capacity of sweetie could make these new kinds of citrus fruits preferable for diets. In summary. the studied citrus fruit has high tot<il phenolics and high antioxidant activities in vitro. Consumption of this fruit may contribute to on adequ<1te intake of antioxidant phytochemicals.