Kinetics investigation of antioxidant capacity and total phenols of low-temperature steeping Bi Luo Chun green tea

Traditionally, tea is steeped in boiled water in Taiwan. In this study, Bi Luo Chun (250 mu g mL-1) steeped at 4, 22, 30, 40 and 50 degrees C reached the saturation of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity at the time of 15, 8, 2, 0.17 (10 s) and 0.17 min (10 s), respectively. The result indicated that tea steeped in cold water (under 22 degrees C) still can reach a saturation of antioxidant capacity in 15 min. However, the initial scavenging rate (% min-1) was quick and decreased with time at all steeping temperatures (r: -0.98 to -1.00). Total phenols and the DPPH scavenging capacity of Bi Luo Chun showed excellent correlation with time. However, the plot of DPPH scavenging capacity vs. total phenols was not always correlated. The result indicated that polyphenol infusion at different times may have a different DPPH scavenging capacity.