Sustainable extraction of phytochemicals from agricultural and food by-products using eutectic solvents and their integration into functional materials

Abstract

Agricultural production plays a vital role in ensuring human nutrition, supplying approximately 80% of the food consumed globally. However, its intensive nature generates substantial amounts of by-products and waste, leading to significant environmental impacts, including soil, air, and water pollution. In this context, the repurposing and valorization of agricultural residues present both a challenge and an opportunity, particularly through the extraction of phytochemicals and nutraceuticals, which exhibit diverse and valuable biological activities. Over the past two decades, deep eutectic solvents (DESs) and their natural analogs (NaDESs) have emerged as promising, sustainable media for phytochemical extraction, offering simplicity, energy efficiency, and tunable properties. As a novel class of designer solvents, DESs are recognized for their green credentials and compositional flexibility, with their physicochemical characteristics largely determined by the nature and ratio of their components. This review summarizes key methodologies for extracting phytochemicals and nutraceuticals from agricultural and agro-industrial by-products and waste, emphasizing the structure-property-function relationships of the DESs employed. It further evaluates the integration of DES-derived extracts into the development of bio-based materials for applications in agriculture, food, and pharmaceuticals. Special attention is given to the physicochemical parameters of DESs that govern their extraction performance and influence the transformation of bioactive compounds into sustainable functional materials, such as eutectogels.Finally, the review outlines future perspectives and critical steps toward optimizing the use of DESs for the valorization of agricultural residues and their conversion into high-value, functional products.