| FRAP, DPPH and ABTS methods were used to determine the antioxidant activities of eight kinds of commercial tea drinks, and Folin-Ciocalteu method was used to determine their total phenolic contents. Results indicated that eight kinds of tea drinks were significant sources of antioxidants in terms of their antioxidant activities and total phenolic contents. In FRAP and ABTS assays, green tea drinks exhibited the highest antioxidant activity with the mean values of TEAC 5 878.66 and 7 266.99 μmol/L respectively, black tea drinks had the lowest antioxidant activity with the mean values of TEAC 2 748.40 and 3 478.71 μmol/L respectively; in DPPH assay, black tea drinks exhibited the highest antioxidant activity with the mean value of VCEAC 20 406.10 μmol/L, and green tea drink had the lowest antioxidant activity with the mean value of VCEAC 17 481.76 μmol/L; total phenolic contents study showed: green tea drinks 450.76 μg GAE/mL >oolong tea drinks 357.91 μg GAE/mL >black tea drinks 247.83 μg GAE/mL. In addition, it was confirmed that total phenolic contents of tea drinks was not always proportional to their antioxidant activities. |
