Grape pomace from Vitis vinifera (Cencibel variety)
was extracted following the method previously reported by Saura-
Calixto et al., 2007. Freeze-dried grape pomace was extracted by
constant shaking at room temperature with methanol–water
(50:50 v/v, 50 mL/g sample, 60 min) and acetone–water
(70:30 v/v, 50 mL/g sample, 60 min). After each extraction step,
samples were centrifuged (15 min, 25 °C, 3000g) and supernatants
were collected. At the end of extraction process,
methanol–water and acetone–water supernatants were combined,
concentrated under reduced pressure at 50 °C, freezedried
and ground to fine powder (sieve ring 0.5 mm). Grape
pomace extract was stored at −20 °C until use