The total phenolics were measured by Folin–Ciocalteu
method as described by Vatai et al. [16] with minormodifications. Half milliliter of appropriately diluted sample
was mixed with 2.5 mL of 0.2 mol/L Folin–Ciocalteu reagent,
and 2.0 mL of sodium carbonate (7.5 g/100 mL) was added
5 min later. The mixture was fully shaken then kept at room
temperature for 2 h. The absorbance of the mixture was measured
at 754 nm against a reagent blank (0.5 mL distilled
water instead of the sample) with a UV–visible spectrophotometer
(Shimadzu UV-1800, Kyoto, Japan). The results were
calculated on the basis of the calibration curve of gallic acid
(GA) and expressed as gallic acid equivalents (mg GAE/g).