Valorization of Wastes from the Food Production Industry: A Review Towards an Integrated Agri-Food Processing Biorefinery

The agri-food sector creates a significant waste stream, mainly due to inefficiencies arising from damage and loss of product throughout the supply chain. Therefore, a thorough utilization of food waste via a bio-refinery approach could play a crucial role in sustainable and zero-waste global development. This article focuses on the current status of valorization routes of selected agri-food processing waste and byproducts within an integrated biorefinery concept. First, the state-of-art extraction technologies for food-waste valorization are described, focusing on apple, tomato, grape, and defatted olive oil pomace as representative substrates. Second, the article investigates a cascade of treatments suitable for the extraction of various useful chemicals. Viable options of integrated biorefineries applied to food waste streams are presented. Selected agri-food processing side streams were divided into two different categories that, in turn, can be valorized through two different integrated combinations. Highly wet residues can be firstly treated by subcritical water to release fermentable saccharides and then valorized by hydrothermal carbonization. Conversely, oily residues can be initially treated using supercritical fluids to extract oils and subsequently converted through anaerobic digestion.