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      Effect of Freeze-Drying on the Antioxidant Compounds and Antioxidant Activity of Selected Tropical Fruits

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          The effects of freeze-drying on antioxidant compounds and antioxidant activity of five tropical fruits, namely starfruit ( Averrhoa carambola L.), mango ( Mangifera indica L.), papaya ( Carica papaya L.), muskmelon ( Cucumis melo L.), and watermelon Citruluss lanatus (Thunb.) were investigated. Significant ( p < 0.05) differences, for the amounts of total phenolic compounds (TPC), were found between the fresh and freeze-dried fruit samples, except muskmelon. There was no significant ( p > 0.05) change, however, observed in the ascorbic acid content of the fresh and freeze-dried fruits. Similarly, freeze-drying did not exert any considerable effect on β-carotene concentration of fruits, except for mango and watermelon, where significantly ( p < 0.05) higher levels were detected in the fresh samples. The results of DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging and reducing power assays revealed that fresh samples of starfruit and mango had relatively higher antioxidant activity. In case of linoleic acid peroxidation inhibition measurement, a significant ( p < 0.05) but random variation was recorded between the fresh and freeze-dried fruits. Overall, in comparison to β-carotene and ascorbic acid, a good correlation was established between the result of TPC and antioxidant assays, indicating that phenolics might have been the dominant compounds contributing towards the antioxidant activity of the fruits tested.

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            Oxidants, antioxidants, and the degenerative diseases of aging.

            Metabolism, like other aspects of life, involves tradeoffs. Oxidant by-products of normal metabolism cause extensive damage to DNA, protein, and lipid. We argue that this damage (the same as that produced by radiation) is a major contributor to aging and to degenerative diseases of aging such as cancer, cardiovascular disease, immune-system decline, brain dysfunction, and cataracts. Antioxidant defenses against this damage include ascorbate, tocopherol, and carotenoids. Dietary fruits and vegetables are the principal source of ascorbate and carotenoids and are one source of tocopherol. Low dietary intake of fruits and vegetables doubles the risk of most types of cancer as compared to high intake and also markedly increases the risk of heart disease and cataracts. Since only 9% of Americans eat the recommended five servings of fruits and vegetables per day, the opportunity for improving health by improving diet is great.
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                Author and article information

                Int J Mol Sci
                International Journal of Molecular Sciences
                Molecular Diversity Preservation International (MDPI)
                20 July 2011
                : 12
                : 7
                : 4678-4692
                [1 ]Department of Food Science, Faculty of Food Science and Technology, Universiti Putra Malaysia, Serdang, Selangor 43400, Malaysia; E-Mails: norshahidams@ (N.M.S); azosman@ (A.O); nazamid@ (N.S); fqanwar@ (F.A.); s_sabrez@ (M.S.P.D); chasecult_me@ (M.R.H)
                [2 ]National Agrobiotechnology Institute, Ministry of Science, Technology and Innovation of Malaysia, Serdang, Selangor 43400, Malaysia
                [3 ]Department of Chemistry & Biochemistry, University of Agriculture, Faisalabad 38040, Pakistan
                Author notes
                [* ]Author to whom correspondence should be addressed; E-Mail: azizah@ or azizahhamid@ ; Tel.: +603-89468374 or +603-89431980; Fax: +603-89423552.
                © 2011 by the authors; licensee MDPI, Basel, Switzerland.

                This article is an open-access article distributed under the terms and conditions of the Creative Commons Attribution license (



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