Toward a green integrated approach for the extraction and separation of biophenols from red wine lees

In the last years, industrial ecology concepts like cradle-to-cradle and circular economy are considered as principles for eco-innovation, aiming at zero waste society and economy where wastes are used as raw material for new products and applications. The winemaking process generates a significant amount of wastes such as grape stalks, grape marc, and wine lees characterized by high contents of biodegradable compounds and suspended solids [1]. Conventional treatments of winery wastes are increasingly expensive, requiring significant amounts of effort, resources, and energy for safe discharge into the environment. On the other hand, wine lees contain high concentration of biophenols well recognized for their potential beneficial effects on human health due to their antioxidant, antimicrobial, antiviral and anti-inflammatory activity. The growing interest in the biological activity of biophenols has intensified research efforts to develop novel and sustainable procedures for their extraction, separation, and purification in an efficient and environmentally friendly manner without affecting their stability. In this contest, membrane processes represent a very powerful alternative to conventional methodologies due to their low operating and maintenance costs, mild operating conditions of temperature and pressure, no use of chemical additives, easy control and scale-up, and high selective separations, ensuring high quality of the produced extracts. Their intrinsic properties well fit the requirements of green and intensified processes. In agreement with a biorefinery approach applied to winemaking, sustainable extractive technologies followed by membrane separation methods have been investigated for the recovery and purification of biophenols from red wine lees before using biomass for energy purposes. Specifically, hydro-alcoholic and aqueous extracts were firstly clarified by using commercial and home-made microfiltration (MF) membranes, in order to reduce their turbidity and to recover phenolic compounds in the permeate stream. Then, the clarified extracts were fractionated with different commercial ultrafiltration (UF) and nanofiltration (NF) membranes in flat-sheet configuration having molecular weight cut-off (MWCO) in the range 150-1000 Da. The performance of selected membranes was evaluated in terms of productivity, fouling index and selectivity towards sugars and bioactive compounds. The obtained results showed that the innovative integrated processes allowed to obtain individual fractions enriched in bioactive compounds of interest for specific applications in pharmaceutical, cosmetic, food, and functional food industries. Overall, they turn up as clean and low-cost methods to valorize red wine lees through the recovery of natural ingredients within the logic of both process intensification and zero discharge strategies [2-3].