Which is the best food emerging solvent: IL, DES or NADES?

Bioactive compounds have been intensely studied because of their biological properties that provide health benefits. However, for chemical or biological applications, these compounds are obtained mostly by using organic solvents. Emergent technologies consider the combination of methods and process optimization to improve the utilization of raw material, decreasing process costs, time and energy consumption. Additionally, due to the arising interest for green processes, alternative solvents have been developed. Ionic liquids (IL), deep eutectic solvents (DES) and, recently, natural deep eutectic solvents (NADES) can show high ability to extract organic, inorganic and polymeric bio-compounds. Overall, these promising solvents are environmentally friendly and less toxic than conventional extraction solvents. This review summarizes the use of IL, DES, and NADES for the extraction of bioactive compounds from natural products, presenting their evolution, process variables, target compounds, extraction techniques employed and future perspectives. The use of these emerging solvents for extraction process has shown to be promising. Besides its high solvation ability and versatility, these solvents may present low or none toxicity. Particularly, it is allowed the use of NADES in food and pharmaceutical formulations, however, some DES and IL are in need of further investigation. IL, DES, and NADES are recyclables and can be related to sustainable processes. Therefore, to expand the applications of these emerging solvents for the recovery of bioactive compounds, the extraction mechanisms involved need to be proper elucidated.