36E-55 |
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K. K. ADOM and R. H. Liu. Dept. of Food Science, Cornell Univ., Stocking Hall, Ithaca, NY 14853-7201 The techniques for total antioxidant activity measurement are valuable in studying the relationship between dietary factors and chronic disease prevention. However, most data in the literature has been on antioxidant activities of water-soluble compounds or food extracts. Total antioxidant activity of foods should include contributions from both hydrophilic and lipophilic antioxidants. The objective of this study was to develop a rapid and sensitive peroxylradical scavenging capacity (PSC) assay for assessing both hydrophilic and lipophilic antioxidants and food extracts. The assay was based on the oxidation of dichlorofluorescein (DCFH) by peroxylradicals generated from thermal degradation of 2,2'-azobis-amidinopropane. Fluorescence produced was monitored at 485nm excitation and 538nm emission. Antioxidant activities of antioxidant compounds and food extracts were calculated and expressed as median effective concentration (EC50). Hydrophilic and lipophilic antioxidant activities of food extracts were expressed as micromol vitamin C eq/g and micromol alpha-tocopherol eq/g, respectively. For hydrophilic antioxidant activity, EC50 values (nmol/mL) were gallic acid (2.25 ± 0.22), Trolox (4.48 ± 0.28), ascorbic acid (4.75 ± 0.83), and catechin (12.15 ± 1.37). Hydrophilic antioxidant activity (micromol vitamin C eq/g) of food samples ranged from 10.16 - 21.23 for fruits, 7.75 - 12.73 for grains, and 0.072 - 1.391 for wine samples. For lipophilic antioxidant activity, EC50 values (nmol/mL) were Trolox (6.00 ± 0.61), a-tocopherol (12.29 ± 1.01), astaxanthin (87.1 ± 4.9), and BHT (319 ± 160). Lipophilic antioxidant activity of grain samples (micromol alpha-tocopherol eq/g) ranged from 3.23 ± 0.54 in wheat to 5.31 ± 0.64 in barley. The assay produced reproducible results over time, and between analyses %RSD was <15%. The PSC assay is simple, rapid, robust, sensitive, and precise. The assay can be routinely used to analyze both hydrophilic and lipophilic antioxidants or food extracts, and will be a valuable alternate biomarker for future epidemiological studies of chronic diseases.
Session 36E, Fruit & Vegetable Products: General
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |