Condensed tannin content in the extracts was determined by the
vanillin/HClmethod ofBroadhust and Jones (1978) with somemodifications. An aliquot of the extracts (1 mL) was added to the vanillin
reagent (2 mL), which had been prepared by dissolving vanillin in
methanol (0.5%, w/v). Sequentially, an aqueous HCl solution (2 mL,4%, v/v) was added to the mixture, and then the mixture was incubated in the dark. The absorbance was measured at 500 nm after
20 min of incubation. To calculate CTC, (+)-catechin standards at
different concentrations (500–3000 g/mL) were used.