## 3 DESs for the Extraction of Bioactive Compounds from Plants, Fruit and Vegetables
UAE is an energetic extraction procedure that can easily break down the structure of cell walls, releasing intracellular substances containing the bioactive compounds. This method is easy and inexpensive and has many advantages such as improved efficiency, reduced extraction time, low solvent consumption, low process temperature, and a high mechanization level compared to conventional extraction methods [25]. DESs have also been used in MAE for active compounds extraction [6], however, this technique is not satisfactory for the extraction of unstable substances because they may cause local overtemperature and require expensive equipment or high energy demand. Alternative extraction techniques based on integrative high-speed homogenization and cavitation-burst extraction (HSH-CBE) technique have been successfully applied to the pretreatments of mulberry to extract anthocyanins [14]. HSH-based procedures can smash fresh plant materials under continuous strong shear and thrust forces, leading to the release of intracellular constituents. Other sample preparation techniques such as homogenizer (HAE), and high hydrostatic pressure (HHPAE) assisted extractions were also applied to phenolic compounds recovery from olive pomace [26]. The last step in all these works is the analysis. In this sense, DESs are normally separated from the target compounds to avoid chromatographic interferences. After extraction with the convenient DES combination, samples are frequently centrifuged and filtered before analysis and bioactivity testing. However, the recovery of extracted bioactive compounds is challenging. Various methods such as supercritical carbon dioxide, antisolvents, and recrystallisation have been studied for the recovery of extracted compounds [20]. Other works reported the recovery of extracted flavonoids from DESs using ultra-pure water as an efficient antisolvent. After separation, water was evaporated by heating at 50 \({}^{\circ}\)C under high vacuum to obtain the DESs for subsequent uses [21]. Sometimes, centrifuged samples are evaporated to remove water and even the NADESs or DESs themselves [14]. However, very often DESs cannot be evaporated due to the high viscosity and extremely low volatility of their components. When necessary, target compounds can be recovered from DESs using macroporous resin column chromatography (e.g., LX-38, AB-8, HPD-450, HP-20) [15; 16; 22]. Thus, the obtained extracts are passed through a prehydrated column and after adsorption, the loaded column is first washed with sufficient deionized water until all the DESs are washed away, then the phenolic compounds can be eluted with a small volume of the most appropriate organic solvent (e.g., methanol). Alternatively, DES extracts are frequently diluted with deionized water to facilitate chromatographic analysis and subsequent spectroscopic or spectrometric measurement by reducing sample viscosity and ionic strength [27]. In fact, many studies do not report solvent removal, performing the analysis and the bioactive characterization of the extracted compounds together with the DESs. Thus, NADESs containing sugars are reported to showed negligible interference in the Folin-Ciocalteu and DPPH assays [26]. HPLC-based methods are the most widespread used in literature for the analysis of DES extracts from plants and vegetables. In particular, methods based on reverse-phase LC with C\({}_{18}\) reverse-phase columns are the most reported. Although UV detector is the most popular choice for quantitative analysis, MS detectors based on IT-MS/MS and QTOF (high resolution MS) are powerful alternatives for phytochemical profiling and characterization of bioactive compounds. For instance, [PERSON] et al. evaluated the presence of the main alkaloids and phenolic compounds present in _P. boldus_ leaf DES extracts by HPLC-DAD-IT-MS/MS and HPLC-(QTOF)-MS/MS [19]. In another work, [PERSON] et al.