Sustainable valorization of grape pomace as source of nutraceuticals

As a consequence of the constant population growing, agro-industrial wastes are gradually becoming one of major causes of the global environmental pollution. Therefore, it is important to find a strategy focused on reusing these by-products, valorizing their potential as a sustainable source of bioactive molecules with health benefits, in order to provide innovative feed and food supplements. In this context, two cultivars of grape pomaces (Cabernet Sauvignon and Petit Verdot) have been selected as starting secondary raw materials to perform preliminary extractions using, as liquid green extracting phases, the so-called Deep Eutectic Solvents (DESs) and hydroalcoholic solutions as reference. The extracts obtained from both fresh and dried matrices were, then, chemically characterized for their phenolic compounds profile through HPLC-DAD. All thirty-six samples analysed contained eight out to thirteen phenolic compounds taken as standards (gallic acid, coumaric acid, syringic acid, caffeic acid, catechin, rutin, quercetin and kaempferol galactoside) with a maximum concentration detected in a single sample of 0.492 μg/g (quercetin). Preliminary DPPH radical photometric assays showed a significant antioxidant activity of the extracts, up to 14935 μM Gallic Acid Equivalents for the sample obtained from dried Petit Verdot pomace using the DES Choline Chloride/Urea (1:2) +40% water as solvent. Molecular biology studies will follow to find a possible correlation between the already proven nutraceutical value of the extracts and variation on selected gene expression.