Grape stalks: From wastes to source of antioxidants and nutraceuticals

Abstract

Wine production is one of the most significant agricultural activities worldwide. The winemaking process generates large amounts of by-products: grape marc, stalks, and exhausted grape marc. Until now, many studies have been focused on marc valorization, very few on stalks. The aim of this research was to deeply explore the potential of residual stalks in the wine industry from a circular economy perspective. Polyphenols were extracted from stalks with new sustainable technologies in the frame of “green chemistry” without the use of hazardous solvents. Extracts were analyzed for total phenolic compound content (TPC) and their antioxidant activity was determined. As polyphenols can have antimicrobial activity, the effect of the extracted polyphenols against wine-spoiling yeast Brettanomyces bruxellensis was determined. The percent reduction of the culture optical density, in the presence or absence of polyphenols, was compared to assess the antimicrobial activity of the samples. The results obtained underline the importance of winemaking by-products (stalks) and their eco-friendly valorization to obtain molecules for food, nutraceutical and cosmetic industries.