Valorization of Soybean Meal: From Conventional Feed Ingredient to Multifunctional Protein Resource for Food, Biotechnology, and Sustainable Applications

Soybean meal (SM) is a by-product of soybean oil extraction and represents one of the most abundant and economically important plant-derived protein resources worldwide. Traditionally utilized as a primary protein ingredient in animal feeding systems, SM has gained increasing attention in recent years due to rising global protein demand, food system pressures, and the need to reduce the environmental footprint of animal-based protein production. In addition to serving as a protein source, SM possesses intrinsic structural and biochemical features that underpin a wide range of functional and bioactive properties. These properties vary with processing conditions, particularly between high-temperature SM (HM) and low-temperature SM (LM). This review provides an integrative analysis of SM by connecting its compositional characteristics, molecular properties, bioactive peptides generation, structure–function relationships, and diverse food and industrial applications. Particular emphasis is placed on the production and biological activities of SM-derived bioactive peptides, processing-driven modulation of structural, functional, and bioactive properties, and emerging applications in human food formulations, industrial biotechnology, and bio-based materials. Agricultural and environmental applications are also discussed, including soil amendment, environmental management, and circular bioeconomy strategies. Finally, life-cycle assessment studies are reviewed to assess the environmental performance of SM-based systems and identify opportunities for improving resource efficiency and reducing greenhouse gas (GHG) emissions. By integrating perspectives from protein chemistry, bioprocessing, food science, industrial biotechnology and sustainability assessment, this work highlights the valorization of SM from a conventional feed ingredient into a multifunctional protein source for the development of high-value food ingredients and industrial bio-based products.