Quality Evaluation of Winery By-Products from Ionian Islands Grape Varieties in the Concept of Circular Bioeconomy

The aim of this work was the study and evaluation of winery by-products in the framework of the circular bioeconomy. Grape seeds and grape skins from Greek Ionian Islands varieties were analyzed in an attempt to provide the appropriate basis for model development of their sustainable exploitation at a local or regional level. The by-products were collected directly from the wineries immediately after the vinification process and were analyzed by chromatographic and spectroscopic techniques. In addition, annual production and yields were estimated. Grape seed oil quality was evaluated based on fatty acid methyl ester (FAME) composition. The grape skins’ phenolic fraction was extracted by an eco-friendly, nontoxic water-glycerol solvent system and was detected qualitatively. In addition, total phenolic content (TPC) and antioxidant activity (ABTS, DPPH) were measured. Based on estimated yields, our results demonstrate that winery by-products have the potential to promote the cyclical bioeconomy in a modern economic growth model that will reduce by-products and environmental costs as they can be reused as whole material in foods, dietary supplements, cosmetic ingredients, food colorants, and preservatives.