BIOTRANSFORMING EU WINE AND DISTILLERY BY-PRODUCTS: GRAPE MARC VALORIZATION VIA EDIBLE FILAMENTOUS FUNGI FOR SUSTAINABLE PROTEIN PRODUCTION

The growing demand for sustainable food systems and resource efficiency has intensified interest in the valorization of agri-food by-products. Grape marc, a major residue from the European wine and distillation industries, poses environmental challenges but offers significant potential for upcycling. This study presents a fungal-based biorefinery approach to convert grape marc into a protein-rich ingredient using edible filamentous fungi: Aspergillus oryzae, Rhizopus delemar, and Neurospora intermedia. Grape marc was hydrothermally pre-treated at 121 °C for 20 minutes to generate liquid cultivation media. Submerged fermentations were conducted under different GM liquor concentrations (2-8%, w/v), pH (3.88, 5.0 and 6.0), and cultivation time (48 and 72 hours). In addition, supplementation with 1 mL/L vitamins and 10 mL/L trace metal solution was tested. Optimal fungal biomass yield and crude protein content was achieved by using 4% GM liquor, at pH 5.0, over 72 hours, with Neurospora intermedia outperforming other strains in both fungal biomass yield and crude protein content. This study highlights the potential of grape marc biotransformation through fungal fermentation, offering benefits such as upcycling into high-value products, improving resource efficiency, supporting sustainable food systems, and opening new avenues for research in biorefineries.