Intensification of polyphenols extraction from grape seeds by high voltage electrical discharges and extract concentration by dead-end ultrafiltration

Grape seed is a rich source of polyphenols. In this study, the high voltage electrical discharges (HVED) were used as alternative method for polyphenols extraction from grape seeds. The extraction efficiency was evaluated by conductivity disintegration index Z and polyphenols concentration in extracts. It was shown that HVED treatment permits effective extraction of polyphenols from grape seeds. The maximal concentration of extracted polyphenols reached 8.3 g GAE/100 wdb after 300 discharges. The extraction of polyphenols was satisfactorily described by the Peleg’s model (R2 > 0.995).Extracts obtained with HVED were then concentrated using membranes with different molecular weight cut off (0.15 μm, 150 and 50 kDa). The dead-end filtration of obtained extracts followed the cake filtration mechanism with membranes UP150 (150 kDa) and UV050 (50 kDa), and the combined mechanism (standard pore blocking/cake filtration) with FSM0, 15PP membrane (0.15 μm). The polyphenols content and physico-chemical properties of the permeates and retentates were evaluated. The polyphenols rejection of 87% and 91% were achieved with UP150 and UV050 membranes, respectively.

► HVED treatment remarkably increases polyphenols extraction from grape seed.
► Filtration of obtained extract follows cake filtration mechanism by lower cutoff membranes (150 and 50 kDa).
► Combined mechanism dominates the filtration with larger pore size membrane (0.15 μm).
► Membranes with MWCO < 150 kDa are suitable for polyphenols concentration from grape seed extract.