3.3.2. Determination of TPC

The TPC was determined by the Folin–Ciocalteu method as follows: (1) Mix 1.9 mL of distilled water and 1.0 mL of Folin–Ciocalteu reagent in a tube, (2) prepare 0.1 mL of the sample solution (2 mg/mL, dissolved by 80% methanol) and add it to the tube, and (3) add 1.0 mL of 20% Na2CO3. The reaction mixture was incubated for 2 h at 25 ◦C. After incubation, the absorbance of the sample was recorded at 765 nm. The results were expressed as milligrams of gallic acid equivalents (GAE) per gram of dry weight (d.w.).
