Effect of Alternative Physical Treatments (Ultrasounds, Pulsed Electric Fields, and High-Voltage Electrical Discharges) on Selective Recovery of Bio-compounds from Fermented Grape Pomace

The aim of this study is to compare alternative treatments on solvent-free extraction of high added value components from fermented grape pomace. Ultrasounds (US), pulsed electric fields (PEF) and high voltage electric discharges (HVED), which are physical treatments able to induce cell damages, were applied on aqueous suspensions of grape pomace. The efficiency of these technologies for phenolic compounds extraction, and particularly for anthocyanins recovery, was evaluated throughout the treatments at equivalent cell disintegration indexes (Z). HVED proved to be the most interesting technique to achieve higher phenolic compounds recovery with lower energy requirement than PEF and US at the same values of Z. However, HVED was less selective than PEF and US regarding the amount of anthocyanins recovered. At equivalent cell disintegration of Z = 0.8, PEF remarkably increased the extraction yield of total anthocyanins up to 22 and 55 % in comparison with US and HVED-assisted extractions. At this Z value, the ratio of total anthocyanins to TPC extracted reaches the respective values of 41.7, 34.9 and 14.1 % for PEF, US and HVED, thus demonstrating interesting differences of selectivity of the treatments.