Antioxidant activity of white, green and black tea obtained from the same tea cultivar

Abstract

The present study explored what effect manufacturing has on the antioxidant properties of teas coming from a single cultivar but processed differently to give a white, two black (Orthodox and CTC) and two green (low-caffeine and non-decaffeinated) teas. Total phenol (TPC), flavonoids (TFC), theaflavins, individual catechins content, and chelating activity were also investigated. Using the ABTS, ORAC and LDL assays the following ‘antioxidant profile’ was obtained: green≥low-caffeine green>white≥black Orthodox>black CTC, with statistically significant correlation between ORAC and LDL assays (r2=0.444, p=0.0067), whereas TPC and TFC significantly correlate with the ABTS one (r2=0.871, p=0.000 and r2=0.438, p=0.007, respectively). Metal chelating activity, which was lowest in the green teas, does not correlate with antioxidant activity but appears to be influenced by theaflavins content. The results contribute to better understand how the manufacturing process influences the antioxidant activity of tea when variables (geographical region, environmental conditions, cultivar type, plucking techniques) are kept to a minimum. Secondly, we show that novel African green, white and black Orthodox teas, made from tea varieties typically used in black CTC tea production, may have potential health benefits comparable with commonly consumed teas.