12.5 ll of Folin-Ciocalteu phenol reagent (50%) was added and allowed
to stand for 30 min at room temperature before the absorbance
of the reaction mixture was read at 650 nm using a plate
reader. Calibration was achieved with an aqueous gallic acid solution
(100–1000 lg/ml). The TPC of the extract was expressed as mg
gallic acid equivalent (GAE) per gram of tea leaves on a dry basis