The total phenolic content (TPC) was determined using the Folin–
Ciocalteu reagent with gallic acid as a standard (Naczk & Shahidi,
1989). Basically, 0.5 ml test sample was mixed with 0.5 ml
Folin–Ciocalteu reagent and 1.5 ml 10% sodium carbonate solution.
After the mixture was reacted for 10 min at 75 C, the absorbance
was read at 760 nm, the absorbance at 760 nm was recorded. Results
were expressed in milligram gallic acid equivalents per gram
of dried sample.