Conventional and Ultrasound-Assisted Extraction: Comparison for Techno-Functional Properties, Sustainability, and Challenges for Plant-Based Food Applications

The growing demand for sustainable protein ingredients has intensified interest in legumes as strategic raw materials for plant-based food applications. Legume proteins, mainly composed of globulins, albumins, vicilins, and legumins, exhibit relevant nutritional and techno-functional properties, including solubility, emulsification, foaming, gelation, and water- or oil-binding capacity. However, conventional extraction methods, particularly alkaline extraction followed by isoelectric precipitation, often involve extreme pH conditions, high water and chemical consumption, long processing times, and possible losses in protein functionality. Ultrasound-assisted extraction (UAE) has emerged as a promising process intensification strategy for improving protein recovery from legume matrices. Its mechanism is mainly associated with acoustic cavitation, which generates microjets, shear forces, shock waves, and microturbulence, promoting cellular disruption, solvent penetration, and mass-transfer enhancement. In addition to increasing extraction efficiency, UAE can induce controlled structural modifications in proteins, potentially improving solubility, emulsifying activity, foaming behavior, and gelation. Nevertheless, excessive sonication may cause aggregation, oxidation, and functional deterioration. This review discusses the principles, effects, advantages, and limitations of UAE for legume protein extraction, emphasizing its potential for the sustainable production of techno-functional plant-based protein ingredients.