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ISHS Acta Horticulturae 773: XXVII International Horticultural Congress - IHC2006: International Symposium on Citrus and Other Tropical and Subtropical Fruit Crops

ANTIOXIDANT ACTIVITY MEASUREMENT IN TROPICAL FRUITS: A CASE STUDY WITH ACEROLA

Authors:   R.E. Alves, E.S. de Brito, M.S.M. Rufino, C.G. Sampaio
Keywords:   radical scavenging activity, free radicals, phenolics, Malpighia emarginata DC
DOI:   10.17660/ActaHortic.2008.773.45
Abstract:
There has recently been a great deal of interest in the antioxidant properties of fruits. Many analyses are being done to evaluate the antioxidant activity of fruits; however, the methods used in these studies are often different. The radical source can affect the antioxidant activity due to the differential response of different types of antioxidant compounds to the specific radical source. Another important factor is sample preparation, since both lipophilic and hydrophilic compounds may have antioxidant activity. In this study we used different methods to assay antioxidant activity in acerola, which is known for its high vitamin C content but also contains carotenoids, anthocyanins, and phenolic acids. We observed dramatic differences among the DPPH (2,2-Diphenyl-1-picryl-hydrazil), ABTS (2,2-azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid)diammonium salt), FRAP (Ferric Reducing Ability of Plasma), and β-carotene bleaching methods. Diverse results were also observed depending on sample preparation (fresh or freeze-dried) and on the extraction fractions TEP (Total Extractable Polyphenols) - methanol/acetone and CT (Condensed Tannins) - HCl/butanol. Other differences were observed between fresh and freeze-dried samples. Our results indicated that we should be careful in interpreting data from different methods and also when comparing different fruits by only one method of sample preparation. We strongly recommend that antioxidant activity measurements must be done by different methods and samples should be prepared in such a way as to extract the diverse compound classes that can be found in fruits.

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