Concentration of bioactive compounds from grape marc using pressurized liquid extraction followed by integrated membrane processes

The integration of pressurized liquid extraction (PLE) with membrane separation technology was used to recover and concentrate monomeric anthocyanins and total phenolics from grape marc. The extracts obtained by PLE were subjected to a preliminary study of stirred dead-end filtration using different commercial flat sheet membranes of nanofiltration (NF). In addition, to reduce membrane fouling and the content of solids in the feed, previous microfiltration (MF) and ultrafiltration (UF) processes were evaluated. The membranes that presented the best performances were selected for cross-flow filtration. The flux of permeate, the retention of bioactive compounds and antioxidant capacity, and the characterization of the membrane surfaces were used to evaluate the performance of the filtration processes. The results obtained in this study suggest that the sequential process based on the previous MF with the MV020 membrane of the grape extract obtained by PLE, followed by the NF step with the NP010 membrane, was the most effective in the concentration of bioactive compounds. The sequential process MV020-NP010 provided excellent results in terms of permeate flux, concentration factor (2.4), retention coefficients of monomeric anthocyanins (78.2%) and total phenolics (71%), and high antioxidant capacity (52%) compared to other tested NF membranes. Fifteen anthocyanins were concentrated in the extracts by UHPLC-UV-Vis. The NP010 membrane had the smallest change in membrane roughness and functional groups after NF. It is concluded that the integration of PLE with the projected sequential process (MV020-NP010) is efficient for the recovery and concentration of bioactive compounds from grape marc, being promising for obtaining functional products with high added value.