Microfiltration for the recovery of polyphenols from winery effluents

• Second racking effluents of red winemaking presents high content of polyphenols.
• Wine lees can be used as raw material for the recovery of polyphenols.
• MSP emerges as a new technology for the polyphenols recovery from winery effluents.
• Polyphenols recovery can be achieved by aqueous extraction and microfiltration.
• Higher dilutions have enabled higher recovery rates of polyphenols.

Winery effluents are attractive sources for the recovery of antioxidant compounds, particularly polyphenols. In this study, the aqueous extraction associated with microfiltration for the recovery of polyphenols present in the effluent (wine lees) from the second racking of red winemaking was investigated. To decrease the charge of the suspended solids and then use the effluent as feed for the microfiltration, dilutions combined with vacuum filtration were tested. In total recirculation mode, two flat-sheet microfiltration membranes (V0.2 and MFP5 membranes) were studied, while in concentration mode a hollow fiber membrane (PAM-Membranas Seletivas) was used. Higher dilution factors of the effluent resulted in higher permeate fluxes, and the membrane with a larger pore size showed higher propensity to fouling. At the optimal conditions, a solution diluted 10 v/v followed by microfiltration led to the achievement of a limpid permeate, rich in polyphenols. This represents a recovery rate of 21% of the total content of polyphenols.