### Lettuce and Chicory Byproducts  
Lettuce (_Lactuca sativa_) and chicory (_Cichorium_ spp.) are commercialized as both whole lettuce heads and as fresh-cut products. Nowadays, there has been a great development of the fresh-cut vegetable industry, with fresh-cut lettuce being one of the most important products. The packing houses dealing with these vegetables produce large amounts of byproducts, mainly outer leaves, stems, and roots. Sometimes these byproducts can reach 50% of the harvested material as in lettuce production. Different approaches have been taken for the valorization of the byproducts, including animal feedstuff and fiber production [98; 99]. In addition, studies have demonstrated that vegetable byproducts are an interesting and cheap source of health-promoting antioxidant polyphenols [100]. Lettuce and chicory byproducts are rich sources of hydroxycinnamic acids and flavonoids, such as caffeoylquinic and caffeoyltartaric acid derivatives, and luteolin, quercetin, and kampferol derivatives, respectively [100]. Sesquiterpene lactones are characteristic constituents of leaves, and they are responsible for the bitterness of chicory. [PERSON] et al. evaluated the content in sesquiterpene lactones of several chicory species, reporting 11(S),13-dihydrolactucin, lactucin, 8-deoxylactucin, 11(S),13-dihydro-8-deoxylactucin, 11(S),13-dihydrolactucopicrin, and lactucopicrin as main components [101]. On the other hand, roots are characterized by high amounts of inulin (starch-like polysaccharide), coumarins, flavonoids, sesquiterpene lactones (lactucin and lactucopicrin), tannins, alkaloids, vitamins, minerals, and volatile oils [102]. Red chicory leaves (_C. intybus_ var. _foliosum_) have been extensively characterized for their phenolic profile, characterized by several hydroxylated benzoic acid and p-coumaric acid derivatives, chlorogenic acids, and flavonoids, among which are quercetin, kaempfer, and apigenin derivatives (e.g., trutin, quercetin-3,4-O-diglucoside, quercetin-3-O-glucose and quercetin-3-O-(6\({}^{\prime\prime}\)-malonyl-glucose), apigenin-7-O-glucose, kaempfer-7-O-glucose). Important constituents of red chicory leaves are the anthocyanins, which are responsible for their dark-red color. Among these, several cyanidin (e.g., cyanidin-3-O-glucose, cyanidin-3-O-(6\({}^{\prime\prime}\)-malonyl-glucose) and cyanidin-3,5-di-O-(6\({}^{\prime\prime}\)-O-malonyl-glucose)), delphinidin (delphinidin 3-O-(6\({}^{\prime\prime}\) malonyl)-glucose), and pelargonidin (pelargonidin-3-O-monoglucuronide) derivatives have been reported [103; 104], and they have been associated with the antioxidant and antiproliferative activities of red chicory [105; 106; 107]. Red chicory whole leaves and polyphenol-rich extracts have already been evaluated for their nutraceuticaltial potential, showing significant antioxidant, cytoprotective, and antiproliferative effects in vitro [105; 106]. Chicory fermented with _L. plantarum_ and _L. hilgardii_ shows an increase in antioxidant and antimicrobial activities due to the release of phenolic compounds, such as gallic acid protocatech acid, chicoric acid, chlorogenic acid, and several degradation products of these phenolics [25]. Red chicory extract has also been evaluated as a natural antioxidant for the food and feed industries, showing an effective reduction in lipid peroxidation of different oils [59]. Green Extraction of Bioactive Compounds from Chicory Byproducts  
In a work published by [PERSON] et al., the authors compared the extraction efficacy of MAE in water with conventional solvent extraction performed under heating, focusing on total polyphenols [108]. The MAE was performed with a domestic microwave oven at 750 W for 2 or 4 min, assaying different solid-to-liquid ratios. Although, in any case, the extraction efficacy of MAE was lower than conventional solvent extraction, the MAE performed at 750 W for 4 min achieved a total phenolic yield of almost 400 mg/kg of fresh material.