Comparison of the contents of the main antioxidant compounds and the antioxidant activity of white grapefruit and his new hybrid

The aim of this study was to compare the main antioxidant compounds content and the antioxidant activity of white grapefruit and his new hybrid (Jaffa Sweeties). Total phenols were measured colorimetrically using the Folin-Ciocalteu reagent, phenolic acids-by HPLC, anthocyanins and flavonoids-spectrophotometrically. The antioxidant activity of these fruits was determined by total antioxidant activity (TAA) and nitric oxide (NO) methods. Trans-hydroxycinnamic acids (caffeic, p-coumaric, ferulic, and sinapic) were more abundant in white grapefruit than in his hybrid. However, on a fresh weight basis, grapefruit's hybrid has a higher total phenol content as well as a higher antioxidant capacity in comparison with white grapefruit. A linear relationship existed between TAA and anthocyanins (R-2 = 0.8068), TAA and flavonoids (R-2 = 0.9320) and TAA and total phenols (R-2 = 0.9446). Our findings indicate the following: (1) Both studied fruits contain a high concentration of natural antioxidants that have not only a high antioxidant activity, but also a good antioxidant quality. (2) The total phenol content and the antioxidant potential are significantly higher in the grapefruit hybrids than in white grapefruits. (C) 2003 Swiss Society of Food Science and Technology. Published by Elsevier Ltd. All rights reserved.