Integrated Biorefineries for Food Waste and Food-Processing Side Streams Through Feedstock-Oriented Design and Sustainable Process Integration

Food waste represents a renewable carbon resource with considerable potential for the production of bioenergy, platform chemicals, biomaterials, and other high-value products within integrated biorefinery systems. However, the heterogeneous composition of food waste, together with the diversity of available conversion technologies, complicates the selection of efficient and economically viable valorization strategies. Successful food-waste valorization requires a systems-oriented approach that integrates individual technologies with feedstock characteristics, pretreatment, conversion pathways, and resource recovery into coherent biorefinery configurations. This structured critical review synthesizes literature identified through Scopus, Web of Science Core Collection, and ScienceDirect for the period January 2015–September 2026, and critically examines the evolution of food-waste biorefinery concepts from conventional processing to integrated, cascade, circular, and near-zero-waste systems, highlighting their engineering principles, advantages, and limitations. Current pretreatment technologies and biological, chemical and thermochemical conversion pathways are comparatively evaluated with respect to process performance, technology readiness and industrial applicability. Particular attention is given to integrated biorefinery design, emphasizing feedstock-oriented process selection, cascade valorization, process integration and resource recovery. The complementary roles of life-cycle assessment, techno-economic analysis, circularity metrics and technology readiness are discussed as key tools for supporting decision-making and industrial implementation. Future progress will depend on combining mature conversion technologies with digitalization, adaptive process management and integrated system design to maximize resource efficiency while advancing the transition toward a sustainable circular bioeconomy.