2.8. Total phenolics content (TPC)
The amount of TPC in extracts was determined according to the
Folin–Ciocalteu’s spectrophotometric (2501 PC Shimadzu, Kyoto,
Japan) procedure (Singleton and Rossi, 1965) using gallic acid (GA)
as a standard for the calibration curve. The linear reading of the
curve was from 0 to 350 mg of GA mL1. Samples were mixed with
0.25 N Folin–Ciocalteu reagent and after 3 min 0.2 M sodium
carbonate solution was added and incubating for 60 min. Results
were read at 724 nm and expressed as mg of GA equivalents per g
of fresh weight (mg eq GA g1 FW).