The Effects of Various Extraction Conditions on Unfermented and Fermented Rooibos Tea Polyphenol Contents and Their Antioxidant Activity

In this study, we determined how unfermented and fermented rooibos tea (RT and GRT) amounts, tea leaf weight, extraction time, and temperature influence 1, 1-Dipheny1-2-Picrylhydrazyl (DPPH) radical-scavenging activity, and total polyphenol and aspalathin contents. When RT and GRT were obtained through steeping 1.5, 2.5, 5, or 10 g of tea leaves in 500 mL of boiling water for 10 min, the total polyphenol and aspalathin contents and the DPPH radical scavenging activity increased with the increase in the amount of tea leaves used. When 10 g of tea leaves were extracted using 500 mL of boiling water for 10 min, the total polyphenol and aspalathin contents and the DPPH scavenging activity of GRT (about 940 mu g/mL, and 5.9 mM ascorbic acid equivalent, respectively) were higher than those of RT (about 760 g/mL, and 3.6 mM ascorbic acid equivalent, respectively). When 5 g of tea leaves were extracted using 500 mL of boiling water for 15-20 min, the total polyphenol and aspalathin contents and the DPPH scavenging activity of RT and GRT were higher than those extracted in 5-10 min. Notably, we observed almost no difference in the total polyphenol and aspalathin contents of RT and GRT when extracted at 80 degrees C compared to decocted for 10 min.