Phenolic Content and Antioxidant Potential of Wine Extracts

Background/Objective: Phenolic compounds are considered to be the most important parameters of wine quality, contributing not only to its organoleptic characteristics, but to various health benefits associated with wine consumption. Although these are successfully extracted from grapes and winemaking by-products, there is no data on extraction from wine itself. This is particularly interesting in light of the fact that the variability of wine polyphenols is not only attributed to the stage of grape ripening and genetic or environmental factors; it is affected by both the vinification process and wine maturing, resulting in indeterminable reactions and transformations that lead to a unique complex composition. Materials and Methods: A liquid-liquid extraction was conducted in accordance with the Kutscher-Steudel procedure. Five Montenegrin wines were used, including the autochthonous varieties Krstač, Vranac and Kratošija. The contents of total phenolics (TPC), flavonoids (TFC), tannins (TTC), and anthocyanins (TAC) were analyzed. To assess the antioxidant potential, the 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity (DPPH) assay and the ferric-reducing antioxidant power (FRAP) assay were employed. Results: TPC was found to be similar in all extracts with the concentration of gallic acid equivalents ranging from 40.38 to 63.11 mg/g. TFC, TTC and TAC exhibited considerable variation, with values 4.27-38.73 mg/g quercetin equivalents, 7.03-20.53 mg/g tannic acid equivalents, and 0.08-10.91 mg/g malvidin-3-glucoside equivalents, respectively. The results indicate that red wine extracts exhibited strong to moderate antioxidant activity (DPPH IC 50 31.15-105.1 µg/mL; FRAP 17.29-43.52 mmol Fe 2+ /g), while white wine extracts demonstrated moderate to weak efficacy (DPPH IC 50 93.76-424.91 µg/mL; FRAP 8.77-30.82 mmol Fe 2+ /g). Conclusion: This study presents an alternative method for the extraction of phenolic compounds from wine. The results obtained are the first contribution to this aspect of the use of wine, forming a possible basis for further research aimed at exploitation in the fields of pharmacy, cosmeceuticals and agriculture.