Lebensm.-Wiss. u.-Technol. 37 (2004) 337–343 Comparison of the contents of the main antioxidant compounds and the antioxidant activity of white grapefruit and his new hybrid Shela Gorinstein a, * ,1 , Zofia Zachwieja b , Elena Katrich a , Elke Pawelzik c , Ratiporn Haruenkit d , Simon Trakhtenberg e , Olga Martin-Belloso f a Department of Medicinal Chemistry and Natural Products, School of Pharmacy, The Hebrew University-Hadassah Medical School, P.O. Box 12065, Jerusalem 91120, Israel b Department of Food Chemistry and Nutrition, School of Medicine, Jagiellonian University, Krakow 30084, Poland c Institute of Agricultural Chemistry, Georg-August University, G . ottingen D-37075, Germany d Department of Agricultural Industry, Faculty of Agricultural Technology, King Mondkut Institute of Technology, Lankrabang, Bangkok, Thailand e Kaplan Medical Center, Rehovot, Israel f Department of Food Technology, University of Lleida, Lleida, Spain Received 24 May 2002; accepted 7 October 2003 Abstract 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 ¼ 0:8068), TAA and flavonoids (R 2 ¼ 0:9320) and TAA and total phenols (R 2 ¼ 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. r 2003 Swiss Society of Food Science and Technology. Published by Elsevier Ltd. All rights reserved. Keywords: Citrus fruits; Total phenols; Phenolic acids; Antioxidant potential 1. Introduction It is widely accepted that fruits and vegetables have many healthful properties (Hertog et al., 1995). Con- sumption of fruits is beneficial to health and contributes to decrease of the mortality rate of cardiovascular and other diseases (Vinson, Dabbagh, Serry, & Jang, 1995; Wang, Cao, & Prior, 1996; Joshipura et al., 1999). A high intake of fruits also reduces blood pressure (Ascherio et al., 1992). In the Health Professionals Follow-up Study it was shown that citrus fruits play a special role in decreasing the risk of ischemic stroke (Joshipura et al., 1999). A prospective study of diet quality and mortality in women proved a significant inverse correlation of mortality with increasing con- sumption of healthy food (Miller, Appel, & Risby, 1998). This positive influence is attributed to some natural antioxidant phytonutrients (Rice-Evans & Dip- lock, 1993; Halliwell, 1994; Rice-Evans & Miller, 1994; Rice-Evans, Miller, & Paganga, 1996). It was shown that plant phenols such as flavonols, anthocyanins, and phenylpropanoids might act as antioxidants or as agents of other mechanisms contributing to cardioprotective action (Vinson et al., 1995; Wang, Cao, & Prior, 1997). ARTICLE IN PRESS Abbreviations: TAA, total antioxidant activity; TE, Trolox equivalent; NO, scavenging activity against nitric oxide; AE, antioxidant efficiency *Corresponding author. Tel.: +972-2-6758690; fax: +972-2- 6757076. E-mail address: gorin@cc.huji.ac.il (S. Gorinstein). 1 Author is affiliated with the David R. Bloom Center of Pharmacy. 0023-6438/$30.00 r 2003 Swiss Society of Food Science and Technology. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.lwt.2003.10.005