*4.3. Evaluation of Total Polyphenols in POE*

Total polyphenol (TP) content in POE was evaluated using Folin–Ciocalteu's method, as previously described [8]. Briefly, for the determination of TP in POE, 100 μL of Folin– Ciocalteu (Folin–Ciocalteu phenol reagent diluted 1:10 in H2O) was added to scalar volumes of POE. After a 5 min incubation at room temperature, 80 μL of 7.5% sodium carbonate solution was added for another 2 h. Absorbance at 595 nm was recorded with a microplate reader. Gallic acid (0.5 mg/mL) was used as a reference to determine the TP values. TP is expressed as mg of gallic acid equivalents (GAE) per mL.
