Saperavi Wine By-Products as a Sustainable Source of Bioactive Polyphenols: Phenolic Composition and Antioxidant Potential

Grape-derived polyphenols have gained increasing attention due to their antioxidant, anti-inflammatory, and cardioprotective properties, which are relevant in the prevention of cardiovascular and neurodegenerative diseases. This study investigates the phenolic composition and antioxidant activity of Saperavi (Vitis vinifera L.) winemaking by-products obtained from the Kakheti region of Georgia. Unfermented and fermented grape skins and seeds were analyzed for total phenols, flavonoids, catechins, leucoanthocyanins, and DPPH radical-scavenging activity. The results demonstrate that unfermented materials retain significantly higher concentrations of bioactive compounds compared to fermented residues, indicating substantial transfer of phenolics into the wine matrix during fermentation. Unfermented grape seeds exhibited the highest phenolic content, while grape skins showed strong antioxidant activity. These findings highlight the potential of Saperavi by-products as sustainable raw materials for the development of natural antioxidant formulations. The study supports the valorization of winemaking residues within a circular bioeconomy framework and their potential application in nutraceutical and functional food industries.