Olive oil dregs (OOD), which are an underutilized by-product from oil mills, were used for the extraction of antioxidant compounds. The residues from three oil mills located in Campania (Southern Italy) were extracted with acidified methanol, and hydroxytyrosol (HT) was the main phenolic compound detected. Total phenolic content (TPC) and HT amount were measured. EVO Campania oil mill provided the residue with the highest TPC and HT quantities: 6.801 ± 0.159 mg Gallic Acid Equivalents (GAE)/g OOD and 519.865 ± 9.082 µg/g OOD, respectively. Eco-friendly extractions at different temperatures and times were performed on EVO Campania OOD, obtaining 9.122 ± 0.104 mg GAE/g OOD and 541.330 ± 64.087 µg/g OOD for TPC and HT, respectively, at 121C for 60 min. Radical Scavenging Activity (RSA), Superoxide Scavenging Activity (SSA), and Ferric Reducing Antioxidant Power (FRAP) were measured in OOD aqueous extracts. Extract prepared at 37C for 60 min showed the greatest RSA and SSA values (44.12 ± 1.82 and 75.72 ± 1.78, respectively), whereas extract prepared at 121C for 60 min exhibited the highest FRAP value (129.10 ± 10.49 µg Ascorbic Acid Equivalents (AAE)/mg). OOD extracts were able to protect sunflower oil from oxidation for 4 weeks at 65C. The overall results suggest that this novel residue can be usefully valorized by providing HT-rich extracts to use as antioxidant agents.

Winemaking generates huge quantities of waste streams represented by leaves, stems, pomaces (including grape skins and seeds) and lees. Conventional treatments of winery wastes are increasingly expensive, requiring significant amounts of effort, resources and energy for a safe discharge into the environment. Among wastes, grape pomaces and wine lees constitute a valuable source of phenolic compounds (flavonoids, tannins and benzoic acids derivatives) which are biomolecules of both technological and nutraceutical interest, acting as antioxidants in biological matrices through the inhibition of lipid peroxide radicals and reactive oxygen species [1]. In agreement with industrial ecology concepts, like cradle-to-cradle and circular economy, the need to recycle, reuse and recover valuable chemicals from waste and wastewaters has become a major topic in wine processing industry [2,3]. In this work, the combination of eco-friendly extraction techniques with membrane-based operations has been implemented in two different case studies in order to develop a sustainable process for the extraction and separation of phenolic compounds from wine by-products. In the first approach, a microwave/hydro-alcoholic extraction, followed by the clarification and fractionation of the hydro-alcoholic extract, was studied for the recovery of phenolic compounds from red wine lees. Specifically, commercial polymeric membranes with a molecular weight cut-off in the range 150-1,000 Da were tested to fractionate the hydro-alcoholic extract clarified by microfiltration. The second case study was focused on the recovery of phenolic compounds from red grape pomace through a combination of ultrasound-assisted enzymatic extraction and membrane fractionation with cellulose acetate laboratory-made nanofiltration membranes. In both cases the performance of selected membranes was evaluated in terms of productivity, fouling index and selectivity towards target compounds. Typical rejections of nanofiltration membranes to different compounds of the grape pomace extract are illustrated in Figure 1. The investigated processes represent an option of sustainability for the winery industries since the obtained fractions could be used as high value-added products due to their antiradical properties.

The underutilised forest and industrial biomass of Castanea sativa (Mill.) is generally discarded during post-harvest and food processing, with high impact on environmental quality. The searching on alternative sources of natural antioxidants from low-cost supplies, by methods involving environment-friendly techniques, has become a major goal of numerous researches in recent times. The aim of the present study was the set-up of a biomolecules extraction procedure from chestnut leaves, burs and shells and the assessing of their potential antioxidant activity. Boiling water was the best extraction solvent referring to polyphenols from chestnut shells and burs, whereas the most efficient for leaves resulted 60% ethanol at room temperature. Greatest polyphenol contents were 90.35, 60.01 and 17.68 mg gallic acid equivalents g-1 in leaves, burs and shells, respectively. Moreover, flavonoids, tannins and antioxidant activity were assessed on the best extract obtained from each chestnut by-product.