Effects of extraction solvents on concentration and antioxidant activity of black and black mate tea polyphenols determined by ferrous tartrate and Folin-Ciocalteu methods

Effect of the use of water and different organic solvents such as acetone, N,N-dimethylformamide (DMF), ethanol or methanol at various concentrations on the total polyphenol content and antioxidant activity was studied for the black tea and mate tea. Polyphenol contents of extracts were determined using ferrous tartrate (method # 1) and Folin-Ciocalteu (method # 2) assays. For black tea, 50% DMF extract showed the highest polyphenol content of 131.9 mg/g and 99.8 mg GAE/g by method # 1 and method # 2, respectively. For mate tea, 50% acetone showed the highest polyphenol content of 132.5 mg/g and 120.4 mg GAE/g by method # 1 and method # 2, respectively. Fifty percent ethanol extract from mate tea and 50% acetone from black tea had the greatest antioxidant activity. The results showed that solvent with different polarity had significant effect on polyphenol content and antioxidant activity. A high correlation between polyphenol content and antioxidant activity of tea extracts was observed. (c) 2005 Elsevier Ltd. All rights reserved.