Mapping Food Industry Side-Streams in Italy: A Quantitative Estimation and Valorization Framework for Major Agri-Food By-Products

The agri-food sector generates significant quantities of by-products and waste biomass, representing both an environmental challenge and an opportunity for resource recovery within a circular bioeconomy. This study developed a decision-support framework for the sustainable valorization of major residues from the Italian agri-food sector. Following a Material Flow Analysis (MFA) of multiple Italian agri-food supply chains, tomato and grape supply chains were selected as representative case studies because they generated the largest quantities of valorizable by-products among the agri-food sectors evaluated, namely tomato pomace and grape marc. MFA based on FAOSTAT and PRODCOM data (2019–2023) was combined with a literature review to assess biomass availability and physicochemical characteristics. The analysis identified tomato pomace and grape marc as the predominant residues. Tomato pomace showed high moisture content (63.34%), balanced organic composition, and a favorable C/N ratio, supporting its suitability for anaerobic digestion with an average biomethane potential (BMP) of 0.143 m3 CH4/kg TVS. Conversely, grape marc exhibited a carbon-rich lignocellulosic structure, with a carbon content of 47.67%, C/N ratio of 24.73, and BMP of 0.195 m3 CH4/kg TVS, favoring thermochemical conversion pathways, particularly pyrolysis. The framework also highlights the importance of cascading strategies, prioritizing the recovery of high-value compounds, and pretreatment approaches to improve biomass conversion efficiency. Overall, this approach supports optimized resource recovery and sustainable agri-food waste management.