Ultrasound-assisted extraction of proanthocyanidins from vine shoots ofVitis vinifera

Proanthocyanidins are high added value polyphenols which have received considerable attention for their health-protective activities. An alternative vine-shoots exploitation as a cheap source of proanthocyanidins obtained by ultrasound-assisted extraction was studied. Amplitude (50–100%), liquid-to-solid ratio (L/S) (50–100 mL/g) and extraction time (10–30 min) were the variables studied by Box–Behnken design to maximize extraction of oligomeric proanthocyanidins (OPCs) and polymeric proanthocyanidins (PPCs) extracted from vine shoots at 80°C. Under the optimal conditions found and validated the OPCs resulted 89.18 ± 0.08 mg catechin /100 g DM and the PPCs 95.46 ± 0.65 mg catechin /100 g DM. The total proanthocyanidins content found in vine shoots was 1.82 mg/g DM and resulted higher than those reported for barley, whole grain rice and stored vine shoots.