Fig. 2.

Effects of methods of burdock root tea (BRT) preparation on antioxidant activities. In order to elucidate the effects of BRT preparation conditions on antioxidant activity, roasting number and tea extraction time were varied. Burdock roots were roasted 0, 3, or 6 times, and BRT was produced by boiling these roasted burdock roots (1.00 mg/mL) for 30 or 60 min at 100°C. Total antioxidant capacities of BRT were determined based on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity (A), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity (B), ferric reducing capacity (C), copper chelating activity (D), total polyphenol contents (E), and flavonoid contents (F). Results are expressed as the mean±standard deviation (n=6). Mean sharing the same letter (a–e) are not significantly different at the 5% level. AA, ascorbic acid equivalent; TE, Trolox equivalents; GAE, gallic acid equivalents; CE, catechin equivalents.