Chemical characterization of the cultivar ‘Vinhão’ (vitis vinifera L.) grape pomace towards its circular valorisation and its health benefits

Among the most significant and productive agroindustries worldwide is the wine business. This agroindustry generates millions of tons of biological residues, carrying huge negative impacts related to the disposal of these materials into the environment. Nevertheless, these byproducts present a high potential for developing new products, contributing to the circularity of this economic sector. In this study, the chemical composition of the grape pomace (GP) obtained from the vinification process (2018 campaign).) of red grapes of the Portuguese cultivar ‘Vinhão’ was determined. The analyses of the pH, proximate composition (moisture content, proteins, lipids, ashes, fibers, and carbohydrates), the total phenolic compounds (Folin Ciocalteau method), and the mineral and fatty acid composition were carried out in triplicate, and the results expressed on a dry matter basis. After dehydration of ‘Vinhão’ GP, this very acidic by-product showed the following proximate composition (%): moisture, 3.43 ± 0.86; ash, 8.20 ± 0.017; lipids, 3.38 ± 0.11; proteins, 9.85 ± 0.51 and 3.28 ± 0.04; dietary fiber, 49.37 ± 1.75; carbohydrates, 35.47 ± 2.35. The content of total phenolic compounds was 35.35 ± 3.61 mg GAE/g. GP also revealed to be an excellent source of K, Ca, Fe, Mn, as well as of arachidic acid. The results obtained in this study suggest that GP from the Portuguese cultivar ‘Vinhão’ is feasible to enrich the nutritional value of food and feed. Moreover, the integration of pomace flour in food and feed is a viable option for reducing the environmental impact and adding value to the by-product, responding to the circular economy challenges.