Open Access

Jonas Bergrath, Marc B. Williams, Hans-Willi Kling, Margit Schulze

• Polyphenols, a diverse group of phytochemicals, are an indispensable component of the antioxidant defense system, given their capacity to neutralize free radicals and modulate redox reactions. This review examines the chemical diversity and antioxidant potential of polyphenols derived from viticultural byproducts, including grape skins, seeds, pomace, and stems. These biomass sources provide a sustainable reservoir of bioactive compounds with potential applications in the development of functional and biobased materials. This review also addresses the methodological challenges inherent to this field, such as the variability of extraction procedures and test conditions. This study critically examines the influence of the structural characteristics of polyphenols, including the number, nature, and distribution of hydroxyl groups as well as molecular size, on antioxidant activity. Additionally, innovative extraction techniques that enhance yield and bioactivity are presented and evaluated. Besides conventional monomeric and oligomeric polyphenolic compounds, lignins, a class of high-molecular-weight polyphenols of industrial importance and stability in oxidative environments, are addressed. The results underscore the necessity for standardized multiassay approaches to precisely assess antioxidant capacity and facilitate targeted polyphenol application in diverse fields. Future research should address the intricate interplay between biomass composition, extraction parameters, and polyphenol functionality to tailor their utilization.