Extraction of bound phenolics
To extract bound phenolics the residues obtained above were
re-washed using 20 mL of redistilled water. After water removing,
samples were blended twice with 20 mL of 4 M NaOH for 2 h in an
ultrasonic bath. The mixture was then adjusted to pH 4.55.5
using 6 M HCl. After centrifugation at 4321g for 25 min, supernatant
was used as bound phenolic extract .