The amount of total phenolic content (TPC) was
determined using Folin–Ciocalteu method (Abu Bakar
et al., 2009). Briefly, 0.25 ml of gac juice were taken into
a test tube. To this solution, 1.25 ml of Folin–Ciocalteu
reagent (10x dilution) were added and the tube was
shaken thoroughly. After 5 min, 0.2 ml of sodium carbonate
solution (7.5% w/v) were added and the mixture was
incubated at 50ºC for 5 min with intermittent shaking.
Absorbance was measured at 760 nm using spectrophotometer.
The total phenolic content was expressed as
gallic acid equivalents (GAE) in μg per ml sample.