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Author: search.filters.author.Katrich, ElenaSubject: search.filters.subject.Citrus fruits

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    Characterization of blond and Star Ruby (red) Jaffa grapefruits using antioxidant and electrophoretic methods
    (2006-03-01)
    Gorinstein, Shela
    ;
    Drzewiecki, Jerzy
    ;
    Park, Yong Seo
    ;
    Jung, Soon Teck
    ;
    Kang, Seong Gook
    Antioxidant and electrophoretic methods were used to characterize the quality differences between blond and Star Ruby (red) grapefruits. Dietary fibre, minerals and trace elements, total polyphenols, anthocyanins, flavonoids, phenolic and ascorbic acids were also determined. The antioxidant potential of red grapefruit was significantly higher than that of the blond fruit (P < 0.05) and correlated well with the total polyphenols (R<sup>2</sup> from 0.8456 to 0.9711). In both the cultivars studied, thirty-two electrophoretic bands were detected [sodium dodecyl-polyacrylamide gel eletrophoresis (SDS-PAGE)]. The main electrophoretic bands occurred between 20 and 43 kDa in both grapefruits with few minor differences between the varieties. Our findings indicate the following (i) red grapefruit is preferable: it has a higher concentration of bioactive compounds and antioxidant potential than the blond; (ii) 1, 1-diphenyl-2-picrylhydrazyl (DPPH) test is a more sensitive method for the determination of antioxidant potential; (iii) there are some minor differences in electrophoretic patterns; (iv) antioxidant and electrophoretic methods are a good combination for characterization of differences of the same citrus fruits. © 2005 Institute of Food Science and Technology Trust Fund.
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    Characterization of antioxidant compounds in Jaffa sweeties and white grapefruits
    (2004-01-01)
    Gorinstein, Shela
    ;
    Cvikrová, Milena
    ;
    Machackova, Ivana
    ;
    Haruenkit, Ratiporn
    ;
    Park, Yong Seo
    Antioxidant compounds and the antioxidative activities of new Israeli citrus fruit sweetie [(Oroblanco, pummelo-grapefruit hybrid (Citrus grandisxC. paradisi)] were compared with the better-known white grapefruit. Total and free phenols were determined with the Folin-Ciocalteu reagent, phenolic acids (free, esters and glycosides) by HPLC analysis and anthocyanins spectrophotometrically. The antioxidant activities were estimated with two scavenging radicals: 2, 2′-azinobis (3-ethylbenzothiazoline-6-sulfonate)- (ABTS) and nitric oxide (NO). Free radical scavenging properties of sweetie and grapefruit were evaluated by β-carotene bleaching (β-carotene). The results of kinetic reactions showed that both fruits differed in their capacities to quench these radicals and sweetie showed more antioxidative activity than grapefruit. Trans-hydroxycinnamic acids (caffeic, p-coumaric, ferulic, and sinapic) were more abundant in grapefruits than in sweeties. High correlation was observed between antioxidative activities and phenols (R<sup>2</sup>=0.94). Both fruits have high concentrations of natural antioxidants with high antioxidative activities. Phenol content 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 total phenolics and high antioxidant activities in vitro. Consumption of this fruit may contribute to an adequate intake of antioxidant phytochemicals. © 2003 Elsevier Ltd. All rights reserved.
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    Comparison of the contents of the main antioxidant compounds and the antioxidant activity of white grapefruit and his new hybrid
    (2004-01-01)
    Gorinstein, Shela
    ;
    Zachwieja, Zofia
    ;
    Katrich, Elena
    ;
    Pawelzik, Elke
    ;
    Haruenkit, Ratiporn
    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<sup>2</sup> = 0.8068), TAA and flavonoids (R<sup>2</sup> = 0.9320) and TAA and total phenols (R <sup>2</sup> = 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. © 2003 Swiss Society of Food Science and Technology. Published by Elsevier Ltd. All rights reserved.