Comparison of peroxyl radical scavenging capacity of commonly consumed beverages.

The antioxidant potential of commercial beverages against peroxyl radical was determined using the Total Oxyradical Scavenging Capacity (TOSC) assay. Peroxyl radicals generated from thermal homolysis of 2,2'-azobis-amidinopropane oxidize alpha-keto-gamma-methiolbutyric acid to ethylene, which is monitored by gas chromatography. The TOSC of each beverage is quantified from its ability to inhibit ethylene generation relative to a control reaction. Nine different beverages (green tea, jasmine tea, black tea, instant coffee, brewed coffee, cocoa mix, oolong tea, prune juice, and grape juice) were selected for this study. Their antioxidant capacities per a cup-serving (125 mL) were measured and compared to peroxyl radical scavenging capacity provided by a recommended daily dose of ascorbic acid (90 mg) dissolved in the same volume of water. The greatest antioxidant capacity was found in brewed coffee, which was followed, in decreasing order, by prune juice, instant coffee, green tea, cocoa mix, grape juice, jasmine tea, black tea, oolong tea, and ascorbic acid. There was an almost 7-fold difference in the TOSC between brewed coffee and ascorbic acid. The data suggest a potential role for commonly consumed beverages in lowering the risk of pathophysiologies associated with peroxyl radical-mediated events.