From Vegetable Oil Production to Integrated Biorefineries: Global Trends, By-Product and Side-Stream Valorization, and Green Extraction Technology Deployment

This review provides a comprehensive assessment of the global production of common edible, specialty, and industrial vegetable oils, with particular emphasis on the generation and valorization of by-products and side-streams within integrated biorefinery frameworks. Attention is given to the main residues generated during oil processing, including oilseed cakes and meals, husks and shells, pomace, refining side-streams, and process wastewaters. The chemical composition of these residues is discussed, highlighting their richness in proteins, dietary fibers, residual lipids, polyphenols, fatty acids, and other bioactive compounds that determine their suitability for downstream valorization. Current management practices are critically assessed, ranging from conventional disposal methods, such as landfilling and incineration, to modern valorization pathways, including anaerobic digestion for biogas production, composting, production of bio-based chemicals, recovery of high-value nutraceuticals, and integration into circular biorefinery models. Special attention is given to green extraction technologies with emphasis on the need for pilot-scale validation, efficient solvent recycling strategies, and integration with existing oil-processing infrastructure. Overall, this review identifies vegetable oil industry by-products and side-streams as technically promising feedstocks for multi-product biorefineries, while emphasizing that industrial implementation will depend on feedstock standardization, solvent recovery and reuse, regulatory acceptance, and integrated techno-economic and life-cycle assessments.