The growing emphasis on sustainable development, resource efficiency, and circularity calls for innovative strategies to minimize waste and maximize the value of industrial processes. One promising approach is to utilize agri-food industrial byproducts, which are often underutilized or discarded, as non-conventional feedstocks for the recovery and production of valuable resources, chemicals, and materials.

Byproducts from a wide range of agri-food industries possess diverse and valuable compositions that offer significant potential for downstream processing and bioeconomy applications. These include pectin from fruit-processing residues, chitin from seafood and mushroom-processing wastes, microbial biomass and sludge from fermentation industries, lignin from pulp and paper processing, and residues from cereal, oilseed, sugar, starch, and dairy industries. However, their potential as sustainable feedstocks for the production of renewable chemicals and advanced materials remains underexplored, particularly in terms of innovative technologies, efficient conversion processes, and integrated resource recovery.

Agri-food industrial byproducts can serve as non-conventional feedstocks for recovering a broad range of valuable resources, including proteins, carbohydrates, lipids, fibers, phenolics, pigments, enzymes, organic acids, platform chemicals, minerals, nutrients, biopolymers, biofuels, bioenergy, adsorbents, catalysts, and advanced carbon-based materials.

By bringing together high-quality research on the valorization and utilization of agri-food industrial byproducts, this Special Issue aims to advance knowledge and innovation in sustainable resource recovery, materials, and chemicals. It will highlight emerging technologies and integrated approaches that transform underutilized byproducts into valuable products, supporting the transition toward a circular economy and zero-waste future. The Special Issue will provide a platform for researchers to explore new pathways for resource efficiency, waste reduction, and sustainable manufacturing.