Chemical characterisation, antioxidant and antimicrobial screening for the revaluation of wine supply chain by-products oriented to circular economy

Aim of the project was the bioassay guided optimisation of extraction methods applied to wine chain by-product to obtain extracts, fractions and biologically active biomolecules with a possible use in the nutraceutical and cosmeceutical industry. Exhausted red and white grape marc were extracted using water:ethanol 50:50 with ultrasound assisted extraction and Naviglio® technology; and also with supercritical fluid extraction (SFE) and steam-distillation obtaining different phytocomplexes. Each extract was characterised by different molecular category: exhausted red grape marc (VCR) by anthocyanins, exhausted white grape marc (VCB) by flavonoids, and grapeseed (VIN) by proanthocyanins. SFE and steam-distillation, instead, highlighted the presence of fatty acids and their ester in every matrix, but terpenoids were not revealed at level major or equal than 0.1%, except for manoyl oxide in VCR (2.89%). VIN was the most abundant matrix in polyphenols (506.24 ± 55.91 mg gallic acid/g dried extract), and it showed the highest antioxidant activity (IC50 of 4.30 μg/mL). Regarding the antimicrobial activity, the hydroalcoholic extracts from VCR, VCB and VIN were tested but no noteworthy activities have been recorded.