Ultrasound-assisted extraction applied to the valorization of agro-industrial residues: Fundamentals, variables, and sustainable perspectives

Ultrasound-assisted extraction (UAE) has emerged as a promising technology for recovering bioactive compounds from agro-industrial waste, streamlining the extraction process by reducing energy consumption, solvent use, and processing time. This review provides an overview of the technique's physicochemical variables and principles, discusses the process's consequences and phenomenological parameters, and examines their implications for yields and outcomes. Recent advances show that UAE, particularly when combined with green solvents such as NADES, has gained relevance because it selectively extracts specific bioactive compounds while minimizing environmental impact. UAE-NADES systems achieve higher yields while improving compatibility with food and pharmaceutical applications. This article also offers experimental recommendations, including integrating emerging technologies and customizing processes through solvent system design, ionic liquids, and supercritical fluids. The critical analysis highlights that the UAE, when properly adjusted and combined with other technologies, is a highly effective strategy for valorizing plant waste and biomass. In conclusion, these technologies can strongly contribute to cleaner, greener, and less environmentally damaging production chains, supporting the concept of a circular bioeconomy.