Determination of total phenols
Total phenol content was determined following the Folin-Ciocalteau
method (Atanassova, Georgieva & Ivancheva 2011). Briefly, 200 μL of
sample or standard solution of gallic acid was mixed with 1.4 mL
deionized water and 100 μL Folin-Ciocalteau´s phenol reagent (2 mol
L-1; Sigma Aldrich; Italy). Total phenol content was
determined using a spectrophotometer (Agilent Technologies, Cary Series
100 UV-VIS Spectrophotometer, Italy) to measure the absorbance at 765
nm, then expressing the results as µmol of gallic acid equivalent.