## 1 Introduction  
In recent decades, the industry of minimally processed vegetables has grown exponentially worldwide. By-products of horticultural commodities significantly contribute to the waste produced by the fruit and vegetable processing industry, which in turn has been demonstrated to be the largest waste emitter into the environment, followed by the household waste generation [1]. Fruits and vegetables generate on average around 25-30% of waste (with peaks of over 50%) that is not further used despite its high contents in several classes of bioactive compounds that can be higher in by-products than in the final products. To better understand the scale of the waste problem, it is appropriate to provide some numerical data concerning specific products. Fruit and vegetable processing generates the following percentages of final products and by-products, respectively: sliced apples (89 and 10%); peeled mandars (84 and 16%); diced papaya (53 and 47%); pineapples (48 and 52%); mango (58 and 42%); artchoke (34 and 66%); asparagus (50 and 50%); onion (83 and 17%); tomato (80 and 20%) [2; 3]. Hence, giving rise to the idea of recovering the bioactive compounds they trap, for example, through the modification of existing microwave drying system in order to both dry vegetables, such as ginger and onions, and, at the same time, collect the vapours containing bioactive components [4], or, in the case of wastewater from edible oil industry, their use to produce biomass, biofertilizers, biopesticides, biofuel, and bioplastics [5]. Chicory and fennel are among the most important vegetables marketed both as fresh and minimally processed products alone (this is the case with chicory) or as an ingredient in salads (fennel). Common chicory (_Cichorium intribus_ L.) is an herbaceous plant of the Asteraceae family, typical of the Mediterranean region but now widely spread in other temperate and semi-arid areas (mid-Asia, northern Africa, eastern USA, Australia), both as a cultivated and wild plant. Chicory has been largely used in animal feed (the bagasse obtained after inulin extraction from roots), in the food industry (as ingredient for salad, for tea blends, as alternative to the more expensive coffee) but nowadays, there is an increasing interest for the extraction of functional compounds present in chicory, such as inulin, oligofructose and sesquiterpene lactones [6]. The interest towards chicory is not exclusively linked to its use as food and food supplement but also to it being a promising source of biologically active substances, such as hydroxycinnamic acids, coumarins and flavonoids, mainly distributed in the aboveground part of the plant, which act as effective immune-correcting agents [7]. Green chicory leaf extract is known to exert in vitro anti-inflammatory effects [8] and preparations obtained from chicory leaves, flowers, and roots have been employed for centuries to treat a great number of diseases in the traditional medicine of several Mediterranean and Asian countries [9]. Metabolic extracts of the spontaneous Romanian chicory species have demonstrated cardio-protective effects on myocardial ischemia and nephroprotection on renal failure in rats [10]. Ethanolic and methanolic extracts of chicory plant have demonstrated cytotoxic activities against cell line MCF-7 and AML, and such activity was related to the antioxidant activity and phenolic content of extracts [11]. According to the authors of that study, extracts can be used to protect or treat cancer cells. Enzyme-treated chicory roots also supplied extracts able to inhibit skin pathogen development in cosmetic formulas submitted to a challenge test [12]. Furthermore, chicory extracts are generally regarded as safe (GRAS) by the FDA and are included in the Everything Added to Food (EAFUS) list [13]. Fennel (_Foeniculum vulgare_) belongs to the Apiaceae/Umbelliferae family and is native to the Mediterranean and Asia Minor areas although the main producing countries are currently India, China, Indonesia, Egypt, and Pakistan.