Conversion of Problematic Winery Waste into Valuable Substrate for Baker's Yeast Production and Solid Biofuel: A Circular Economy Approach

Research background: Wine production, which is considered a major sector in food industry, often involves the use of a large amount of resources. Moreover, wine making generates a large amount of grape pomace, which is generally used for low-value applications such as fertiliser and animal feed. The aim of the present research is to explore the possibility of improving the overall sustainability of traditional winemaking. Experimental approach: A zero-waste process was developed. It includes the production of white wine and the substantial valorisation of grape pomace, which is converted into solid biofuel, tartaric acid and concentrated grape extract as feedstock for industrial baker's yeast production. Results and conclusions: We estimate that a significant surplus of renewable energy of approx. 3 MJ/kg processed grapes can be obtained during this conversion. The suitability of grape extract as a potential substrate for industrial baker's yeast production was evaluated and the feasibility of a partial replacement of molasses (up to 30 %) was demonstrated. Novelty and scientific contribution: We present a circular economy approach for the conversion of winery biowaste into high-value resources such as feedstock and solid biofuel.