Genus Brassica By-Products Revalorization with Green Technologies to Fortify Innovative Foods: A Scoping Review

Food losses and waste reduction are a worldwide challenge involving governments, researchers, and food industries. Therefore, by-product revalorization and the use of key extracted biocompounds to fortify innovative foods seems an interesting challenge to afford. The aim of this review is to evaluate and elucidate the scientific evidence on the use of green technologies to extract bioactive compounds from Brassica by-products with potential application in developing new foods. Scopus was used to search for indexed studies in JCR-ISI journals, while books, reviews, and non-indexed JCR journals were excluded. Broccoli, kale, cauliflower, cabbage, mustard, and radish, among others, have been deeply reviewed. Ultrasound and microwave-assisted extraction have been mostly used, but there are relevant studies using enzymes, supercritical fluids, ultrafiltration, or pressurized liquids that report a great extraction effectiveness and efficiency. However, predictive models must be developed to optimize the extraction procedures. Extracted biocompounds can be used, free or encapsulated, to develop, reformulate, and/or fortify new foods as a good tool to enhance healthiness while preserving their quality (nutritional, functional, and sensory) and safety. In the age of recycling and energy saving, more studies must evaluate the efficiency of the processes, the cost, and the environmental impact leading to the production of new foods and the sustainable extraction of phytochemicals.


Background
Considering that the food supply chain can be divided into four main stages (primary production, processing, retail/distribution, and consumption), the Food and Agriculture Organization of the United Nations (FAO) defines 'food loss' as food discarded along the primary production and processing stages, while 'food waste' is obtained during retail/distribution and consumption [1]. During the last few decades, the European Commission has adopted a set of proposals to make the European Union's (EU) policies fit for reducing net greenhouse gas emissions by at least 55% by 2030, compared to levels in the 1990s [2]. Around 20% of food produced in the EU is lost or wasted, accounting for 8-10% of global [3] and about 6% of total EU greenhouse gas emissions [4], a huge environmental impact. Eighty-eight million tons of food losses and waste are generated each year in the EU, with estimated costs of EUR 143 billion [4]. According to a mass flow analysis, a total of 129 Mt of food losses and waste were generated in the EU in 2011 [5], of which 79% were plant-based products. Among plant-based by-products, 30% and 28% were fruit and vegetables (F and V), respectively [5].
In the primary production steps, the main food losses are due to: (i) non-harvested edible products, (ii) edible products left in the field, (iii) edible products harvested but not

Brassica By-Products and Their Added-Value Compounds
Harvesting broccoli generates a huge number of by-products, mainly leaves, and stalks. Broccoli leaves represent 50% of total plant biomass. Furthermore, compared to broccoli florets or stalks, broccoli leaves have higher total phenolic content (TPC), antioxidant activity (TAC), chlorophylls, and vitamins (E and K), while showing similar glucosinolate (GLS) content [11,12].
In a recent study about valorization pathways, techno-economic constraints, and environmental assessment, information was included about different Brassica processing wastes, such as broccoli (leaves and stalks), cabbage waste, and cauliflower (florets and leaves) [7]. It is shown that the bioactive compounds (GLS, phenolic acids, and flavonoids) can be jointly extracted with other nutrients (vitamins, minerals, and trace elements) using conventional or green technologies. Other phytonutrients and pigments, such as carotenoids, can be extracted from other brassicas, such as cabbage waste. In addition, pectin and dietary fiber can be extracted, whose main sources are the non-edible parts of these vegetables (roots, stalks, florets, or even the pulp obtained from the processing) [11,12].
The main bioactive compounds found in Brassica are the GLS, from which isothiocyanates are biosynthesized and reported to be potent anticarcinogens and antimutagens, as sulforaphane (SFN) or sulforaphene are [13][14][15]. In fact, all the Brassicas present a predominating GLS in their composition, whose accumulation depends on the genotype, variety, cultivar (cv.), growing conditions, developmental stage, type of plant tissue, and postharvest handling. The main GLS in broccoli (Brassica oleracea var. italica) and cauliflower (Brassica oleracea var. botrytis) are glucoraphanin and glucobrassicin [16], while in kale (Brassica oleracea var. sabellica) they are sinigrin, glucoiberin, and glucobrassicin [17], or in cabbage (Brassica oleracea var. capitata) are sinigrin and glucoiberin [18,19]. Other Brassicas, such as mustard (Sinapis alba, Brassica alba, or Brassica nigra), are rich in glucosinalbin [20], while in radish (Raphanus sativus) are glucoraphanin and glucoraphasatin [21,22]. Figure 1 shows the bioactive compound classification of broccoli by-products, which are the most produced worldwide and consumed Brassicas, and hence the main source of by-products. Nevertheless, there are other Brassica by-products with different compositions, i.e., those rich in anthocyanins and carotenoids, as in the case of red cabbage [19], or flavonoids and dietary fiber from cauliflower [23].  [24][25][26][27].

Materials and Methods
Scopus was used for searching the documents included in the present review. The purpose of a scoping review is to provide an overview of the available evidence on a topic by compiling and evaluating the information. "Brassica", "extraction", and "by-product" were used as the search words, and the following items were also used: "broccoli" OR "ultraviolet light" OR "blanching" OR "cutting powdering" OR "enzymatic treatment" Figure 1. Classification of the main bioactive compounds in broccoli by-products. The content is based on published literature [24][25][26][27].

Materials and Methods
Scopus was used for searching the documents included in the present review. The purpose of a scoping review is to provide an overview of the available evidence on a topic by compiling and evaluating the information. "Brassica", "extraction", and "by-product" were used as the search words, and the following items were also used: "broccoli" OR "ultraviolet light" OR "blanching" OR "cutting powdering" OR "enzymatic treatment" OR "ultrasound" OR "microwave". The inclusion criteria were papers published in indexed JCR journals (Q1-Q4), while the exclusion criteria were books, reviews, and scientific articles published in non-indexed JCR journals. To include the most known Brassicaceae, all information related to Brassica extraction by-products was verified by including the terms "broccoli", "cauliflower", "kale", "mustard", "wasabi", "kohlrabi", "cabbage", and "radish". Additionally, Scopus was used to search for studies on healthy or functional foods elaborated with Brassica by-products. "Brassica" AND "by-products", "Broccoli" AND "by-products", "Cauliflower" AND "by-products", "Kale" AND "by-products", or "Mustard" AND "by-products" were used as the search words. For data curation, the title, and abstracts of the works found were analyzed and classified depending on their relevance with the help of Excel. First, the papers not focused on the studied field were excluded. Then the potential papers were subjected to an exhaustive analysis, in which all the papers were checked for inclusion criteria.

Abiotic Stresses to Enhance Bioactive Compounds in Brassica By-Products
It has been widely demonstrated that postharvest abiotic factors like ultraviolet radiation (UV), wounding/cutting, phytohormones, and altered gas composition can be applied to increase bioactive compound biosynthesis in fresh F and V [28]. However, there is less scientific evidence about the effect of such abiotic stresses on the bioactive compounds of their by-products. We have focused on two abiotic stresses as potential tools to increase the bioactive compound content of Brassicas prior to extraction since, in our opinion, they seem to be the most efficient.

Ultraviolet Radiation
The effect of UV on Brassica bioactive compounds (fresh-cut, sprouts, and florets) has been extensively studied [29][30][31][32][33][34][35]. But there is not much scientific evidence studying the effect of UV on Brassica by-product bioactive compounds [36,37]. Single or combined postharvest UV-B and UV-C treatments were previously proposed as an innovative and eco-friendly tool to revalorize broccoli leaves and stalk by-products through the enhancement of their main phytochemicals [36]. Particularly, a 15 kJ m −2 UV-B treatment induced glucobrassicin increases of 135% and 83% in leaves and stalks after 72 h at 15 • C, respectively. Additionally, broccoli leaves showed TAC increments of 120% after UV treatments, while broccoli stalks showed TPC increases of 170-420%, likely due to a higher extraction of some individual antioxidant compounds [36]. Other authors studied the effect of UV (250-400 nm, 59 and 99 kJ·m −2 ) on the leaf waste fraction from industrial trimming of cabbage, reporting an increase of TAC, flavanols, hydroxy-cinnamates, and anthocyanins, while no changes in GLS or isothiocyanates were observed [37]. When UV radiation was combined with photosynthetic active radiation (400-700 nm, 497 kJ·m −2 ) an increase in TAC (30%), the content of five phenolics (from 1.4 to 10-fold higher), and hydroxycinnamic acids were observed [37].

Wounding/Cutting
Cutting or shredding horticultural commodities affects plant metabolism by increasing secondary metabolites with antioxidant potential to fight against the abiotic stress it induces [38,39], for which reason the same trend would happen in their by-products. Recently, the effect of cutting style on the biosynthesis of phenolics and cellular antioxidant capacity in wounded broccoli has been reported [39]. In this study, the TPC increased by 45.5, 58.9, 71.2, and 98.5% in intact heads, intact florets, half florets, and shredded florets, respectively. The authors concluded that wounding stress may be a convenient way to ob-tain, commercially or at home, more health-promoting antioxidant compounds [39]. Other authors indicated that wounding broccoli (florets cut into four pieces), applied alone or in combination with exogenous phytohormones, can be used as an effective emerging technology to allow the accumulation of specific GLS and phenolic compounds [40]. Wounding stress was successfully applied to design a phenolic-rich carrot juice by cutting unpeeled carrots into slices and storing them for 48 h at 15 • C before blanching [41]. However, no scientific studies on the effect of cutting on Brassica by-products have been discovered, indicating that more research in this area is required in the near future.

Extraction Techniques
In the last few decades, sustainable and non-thermal techniques have been optimized to reduce costs due to conventional technologies' high energy consumption and the degradation of thermolabile nutritional compounds and the thermal instability of several bioactive compounds during the process. Therefore, it is essential to focus on innovative non-thermal 'Green Technologies' such as USAE, MWAE, and EAE, among others.
Most studies are focused on fruit by-products [42], finding a lack of clear evidence related to horticultural commodities, including Brassica by-products. Due to the interest in the effect of green and non-thermal treatments on Brassica by-products for phytochemical extraction, a compilation of the scientific evidence is needed to establish the optimum treatments and conditions (extraction, addition, processing, storage, and shelf-life). Additionally, the effect of processing, including blanching, drying, homogenization, and/or grinding into powder, should be studied as pretreatments of extraction techniques.

Ultrasound-Assisted Extraction from Brassica By-Products
USAE consists of the propagation of ultrasonic waves in a liquid medium, inducing a longitudinal displacement of particles that create cavities in the liquid, which is called acoustic cavitation [42]. This can occur with less solvent consumption, energy, and extraction time, making it an environmentally friendly and economical technique [43]. Table 1 shows the main conditions used for USAE of bioactive compounds from Brassica by-products. According to the articles found, broccoli is the main Brassica studied, followed by cabbage, radish, cauliflower, and kale. The revalorization of Brassica by-products is mainly concentrated on leaves and stems, although there are articles focused on seeds. The frequency of USAE equipment ranged from 20 to 50 kHz. Power units depended on the equipment used, reporting values from 100 to 500 W, 50 W/L, or 0.228 W/cm 2 . The best results were achieved with an aqueous solvent. Water was used as the extractant in ten of the studies found, and in seven of them it was combined with an organic solvent (ethanol, methanol, and acetonitrile), with ethanol being the main one [44][45][46][47]. In fact, Liu et al. [48] reported a better SFN extraction with a ratio of 1:10 for water compared to 1:50 for ethyl acetate. The solid:liquid ratio in most of the studies ranged between 1:2 and 1:50, and just one of the studies found that it worked with a more diluted extract (0.06:30) [49]. The extraction temperature used was determined by the target compound or the function to be achieved by the extraction. An extraction temperature below 30 • C was best for the GLS and SFN extractions [23,[46][47][48]50,51]. However, MWAE pretreatment for a short time favored SFN extraction due to the inactivation of the myrosinase enzyme and GLS-SFN conversion. Temperatures above 45 • C were used for the extraction of phenolic compounds [43,47], and in the case of protein extraction, USAE was carried out in some studies [45,52,53]. The extract was dried at 30 • C in a vacuum oven. The residue was mixed with water and recovered by centrifugation (6000 rpm × 10 min).
USAE extracted more bioactive compounds than supercritical fluids but not as many as pressurized liquid. The extract was dried at 30 • C in a vacuum oven.
The residue was mixed with water and recovered by centrifugation (6000 rpm × 10 min). USAE extracted more bioactive compounds than supercritical fluids but not as many as pressurized liquid. [53] Cauliflower by-products cv., drying, and particle size information NA Extracts were combined to metal-organic framework nanocubes. They were dispersed by an ultrasonic probe in 100 mL, then triethylamine as a capping agent was added, and the mixture was agitated and heated for 12 h at 130 • C.
Broccoli extract combined with MOF-5-NCs showed synergistic activity against P.
aeruginosa bacteria in standard and clinical strains. [43] Kale cv. information NA Convective dryer (39 • C) Particle size information NA 20 100 W 80% EtOH 2:40 60 60 USAE in two cycles of 30 min Extracts were filtered, combined, and evaporated. The residues were dissolved in methanol and filtered.
High isolation of phenolic acids and high yield of biocompounds in short time and reduced solvent volume with easy handling. [45] Broccoli seeds cv., drying, and particle size information NA

Microwave-Assisted Extraction from Brassica By-Products
The application of MWAE to enhance extraction consists of the ability to extract bioactive compounds from structural changes in cells due to the electric and magnetic fields generated by this technology. The conditions reported in previous studies to be considered in MWAE are summarized in Table 2. The main studied by-products came from broccoli, cabbage, and radish. Although the cv. is an important parameter to know since the phytochemical content may vary, it was not detailed in the reported manuscripts. The power intensity ranged from 130 to 400 W under atmospheric conditions, except in one study in which vacuum was applied together with MWAE to improve the extractability [18]. The solvents used for MWAE were different in each study, including water, water + ethanol, dichloromethane, nitric acid, or methanol. The most concentrated solid:liquid ratio used was 1:4 [57], and the most diluted was 0.5:31.5 [58]. Both obtained good results, because the extraction conditions (time, solvents, and temperature) were different. The temperature ranged from 20 to 90 • C, always below 100 • C to avoid bioactive compound degradation. The extraction time varied from 1 to 25 min, obtaining the best results with times of less than 20 min.

Enzymatic-Assisted Extraction from Brassica By-Products
EAE is based on the use of enzymes to break down the cell walls of plant material and improve the extraction yield of its bioactive compounds. The main conditions to be considered are shown in Table 3. Most of the Brassica by-products used in the studies come from broccoli, radish, cauliflower, and cabbage. Before EAE, by-products are usually pretreated by grounding and drying (oven at 45-60 • C or using a freeze-dryer), although particle size is rarely detailed. The enzymes used were determined by the compound to be extracted. The main enzymes found were cellulase, hemicellulase, protease, pectinase, and glucanase, among others. Papaioannou and Liakopoulou-Kyrikides [59] used a fungus to facilitate the β-carotene production from Brassica by-products. Other green technologies combined with EAE, such as MWAE [58] and USAE [60], have been used to increase the extraction yield prior to enzymatic rupture of the cell walls. Only half of the articles summarized in Table 3 detail the enzyme inactivation conditions; two of them used heating for a few minutes and one used refrigeration. The solid:liquid ratio ranged from 10:40 to 5:500, like other extraction methods using green technologies. Extraction time was highly variable, ranging from 8.4 to 1200 min, but the temperature was limited between 26 [59] and 68 • C [58].    Decreased the sugar content and increased the uronic acid content. Non-extractable phenolics were found higher in inflorescences and increased with EAE and TAC.

Other Extraction Methods from Brassica By-Products
Although the most commonly cited green technologies in the bibliography have already been described, a considerable number of works have studied other technologies to extract bioactive compounds from Brassica sources. Previous research has shown that extracting pectin from broccoli stalks with 0.1 M nitric acid under reflux for 30 minutes [65] is effective, and that by-products of broccoli florets are an excellent source of glucoraphanin and phenolics after extraction in a thermostatic bath mixed with ethanol (0, 40, and 80%) for 10, 40, or 70 minutes [66]. Nevertheless, despite the recent publication of these works, only the scientific studies that include novel and green technologies to enhance the extraction ability of Brassica by-products are shown in Table 4.
As shown, four works used supercritical fluids, one used ultrafiltration, and another used pressurized liquids. All these techniques showed higher yields for recovering bioactive compounds from Brassica by-products. Nevertheless, such techniques are even more expensive than those previously described and take longer to extract the phytochemicals, although they use lower temperatures (35-60 • C) to avoid their degradation and do not require high amounts of solvents to complete the extraction. The solid:liquid ratio is not a relevant parameter in supercritical fluid technology. However, the solvent flow rate is detailed in almost all the works found as being 2 L/min. Superficial fluid technology facilitated the extraction of bioactive compounds and antioxidants, except in the work of Marinelli et al. [53], where this technology showed the worst results compared to pressurized liquid technology. In acidic conditions, 77% of the phenolic compounds were recovered. Combination of diafiltration with nanofiltration was beneficial only when processing under acidic conditions.
[68] High-quality extract in terms of antimicrobial efficiency against Pseudomonas spp. and Candida krusei. [56] Broccoli stems and leaves cv. Parthenon and Naxos.
Supercritical fluids using CO 2 NA NA NA Two pumps: High yield of β-carotene, phenolic compounds, chlorophylls, and phytosterols. Great TAC.

Brassica By-Products Fortification in Food Matrices
Once the main bioactive compounds have been extracted from Brassica by-products, several possibilities to fortify different food matrices have been reported or could be possible.

Brassica By-Products Processing Pretreatments
Blanching, drying (i.e., convective or freeze drying), and/or grinding into powder are typically used as pretreatments of extraction techniques to increase yield and stability [70]. Apart from the inhibition the enzymatic activity and retaining color and nutrients, several authors indicated that blanching could be a good strategy to enhance the recovery of phenolics and other bioactive compounds during the extraction. The phytochemical content depends on the blanching pretreatment and dehydration process applied, although dehydrated broccoli by-products are a source of pigments, including terpenoids, sulfur compounds, and phenolic compounds [71]. Recommended blanching conditions were three cycles of 2 min at 800 W, with 1 min intercalated, using a domestic microwave oven [71]. Other authors indicated that slicing cauliflower leaves prior to blanching led to higher losses of TAC during either hot water or steam blanching [72]. Water blanching led to lower retention of water-soluble antioxidants as such phenolic compounds and vitamin C [72].
On the other hand, MW hydrodiffusion and gravity (MHG) is a novel technique consisting of a combination of blanching at 100 • C and drying at 100 • C [73]. Ferreira et al. [73] reported that MHG allowed obtaining a rich dry extract from broccoli by-products cv. Parthenon, preserving polysaccharides and proteins with low moisture (12%). Furthermore, Ferreira et al. [71] previously reported the effect of MHG technique on phenolics in broccoli leaves and stalks, showing an increase of 26% TPC, preservation of GLS content, and reduction of pigments (25%). Blanching has also been used to produce chemical-free nano-fibrillated cellulose from cabbage for potential use in food formulations [74]. The authors also indicated that steam blanching of the outer leaves of cabbage was used and then dried in a hot air oven (60 • C, 8 h), and nano-fibrillated cellulose was extracted by heating (130 • C, 2 h), followed by USAE (37 • C, 1 h), or high pressures (40 MPa, 5 times) [74].
After drying, F and V by-product as a powder/flour is commonly acquired by grinding until obtaining the desired particle size [42,70]. This powder could be applied as a solid ingredient for the fortification of different products, or the key bioactive compounds can be extracted from this powder to obtain liquid extracts, which can be freeze-dried or spraydried to obtain powders. Because of differences in diffusivity, particle size is one of the most important parameters influencing the extraction and incorporation of bioactive compounds into other food matrices. Not only must the extraction method be optimized, as stated in Section 5, but so must the drying method. The technique, the time, and the temperature should be selected to avoid the degradation of the biocompounds and to have a stable material (dry by-product) for storage until the extraction. Therefore, this process is of great importance for obtaining the best-quality extracts. Depending on the drying process, the moisture content of the sample varies and influences the extraction step [70]. Apart from the information on blanching processing, there is a lack of specific details related to drying in several pieces of scientific evidence, as previously shown in Tables 1-4. As to Brassica by-products, other authors concluded that powdered Brassica napobrassica leaves sieved at three particle sizes influenced the physicochemical and functional properties of the powder. The addition of this powder to a starch suspension influenced the pasting of the suspension [75]. Other authors obtained a flour (20% leaves, 35% inflorescence, and 45% stems) by freeze-drying broccoli by-products (Naxos cv.) and grinding them (no particle size was specified). They concluded that the daily intake of a high dose of broccoli by-product flour for three weeks was safe because of the high bioavailability of GLS and had no negative impacts on the mouse's health [76].
The use of water-blanching and grinding to obtain encapsulated stalk and floret juice powders by spray-drying using maltodextrin as a carrier was reported. The optimal processing conditions were 5% maltodextrin and a drying temperature of 220 • C. Floret juice powders showed high TPC, while stalk juice powders presented high TAC [77]. Other authors studied broccoli stems and leaves powders, from blanched and freeze-dried juice and pomace fractions, as carriers to encapsulate epigallocatechin gallate aqueous solution (EGCG). They concluded that broccoli by-product puree and pomace had higher adsorption capacities for EGCG than juice at 25 • C, making them promising carriers for delivering and stabilizing EGCG through gastrointestinal digestion [67]. The comparison between conventional and supercritical fluid extraction techniques of different leaf-stem mixes (1:1, 3:1, and 1:3) from Parthenon and Naxos broccoli by-products dried at 55 • C for 24 h and ground into uniform powder was previously studied. The results indicated that supercritical fluid extracts from broccoli by-products could potentially serve as an ingredient for cosmetic purposes [69].
Fermentation can be used for by-product revalorization to promote a circular economy and improve efficiency and profitability in the food sector [70,78]. The aim of one of these studies was to revalue broccoli stalk by designing a novel fermented food product with probiotic potential enriched in glucoerucin, indolic GLS, phenolic acids, and flavonoids [78]. Dried Brassica by-products in powder can be incorporated into whey to evaluate the effect of its supplementation on β-galactosidase enzyme production. Different concentrations (5-25% w/v) of dried cauliflower waste were cut (0.5 cm), oven-dried (50 • C), and ground (1.168 mm). A 15% increase in β-galactosidase production was observed when the cauliflower waste level was increased to 20% compared with whey alone [79].

Brassica By-Product Fortification in Animal Feed to Increase Functionality
The use of Brassica by-products for animal feeding (small ruminants and chicken, among others) allows their transformation into high-quality meat and milk products while promoting the development of the circular economy. Depending on the animal, Brassica by-products could be incorporated into the diet through feed and/or silage to ensure nutritional quality. The effect on milk production, composition, functional properties, and technological characteristics of goat and fermented milk has already been reported [80]. The use of silage from horticultural by-products in the diet of dairy goats has been reported to reduce feeding costs. Long-term inclusion of 40% silage from broccoli by-products, among other commodities, in the balanced diets of dairy goats yields milk suitable for yogurt and cheese fermentation. Broccoli inclusion enhanced the antioxidant properties of milk and, consequently, of fermented milks [81].
Similarly, broccoli by-products have also been incorporated into the feeding of broilers to enhance the meat quality. The incorporation of broccoli extracts with 0.075 g/kg SFN into the broiler diet increased the expression of xenobiotic and antioxidant enzymes in the jejunum of chickens, which represents a novel mechanism to improve the health of farm animals [82]. Hu et al. [83] tested different concentrations (0, 4, 8, and 12%) of broccoli stems and leaves in the corn-soybean meal of broilers during their 42 days of life. The carotenoids content and TAC of the meat improved with 4% broccoli by-products, which also increased the activities of superoxide dismutase and catalase in breast muscle by 8 and 12%, respectively.

Brassica By-Products Fortification in Several Food Matrices
This section has been focused on the scientific evidence related to the use of Brassica by-products for fortification and incorporation into human food matrices. Table 5 includes information about the characteristics of Brassica by-products (drying technique, particle size, and cv.), extraction technique (US, maceration), formulation, incorporation method (liquid extracts, powders), and benefits tested after incorporation (shelf-life, bioactive compound fortification). Table 5 was divided into categories related to Brassica species by-products: broccoli, kale, cabbage, and cauliflower, broccoli and cauliflower being the most common. Broccoli by-product incorporation has been reported in several food matrices in powders, liquid extract, and/or encapsulated, among others: dressing [84], bakery products [85][86][87][88][89][90], dairy products [91,92], snacks [87], fish products [53], and beverages [93], with bakery products being the most common. Broccoli by-product extracts, mostly in solid form, can be considered a promising source for designing new foods with interesting techno functional and functional properties. A pesto sauce was enriched with kale by-products, obtaining several benefits (Table 5) [12]. This research concluded that more studies should be conducted with non-thermal blanching to minimize myrosinase inactivation [12]. A cabbage leaves by-products powder was added into the sponge cake flour to substitute 10% and 20% of wheat flour, enhancing some bakery properties (Table 5) [94]. Some scientific evidence related to the incorporation of cauliflower by-product focused on replacing several ingredients such as wheat flour in snacks [95], carrageenate of vegan paté [96], dried whole egg and starch in a quiche [96], and xanthan in tomato sauce [96]. The aim of the remaining evidence was the enrichment of several food matrices with cauliflower by-products: chicken soup [97], pork patties [98], and apple juice [52]. Higher content of proteins and minerals. Improved specific volume and bake loss. Improved TAC and anti-aging activity.
Products underwent discoloration (more yellowish) and a decrease in firmness and adherence, which could limit their potential as fiber supplements. Hardness and adherence decreased in floret and stem formulations.   Viscosity increased when cauliflower fiber was added before cooking (in the case of the floret and mainly the stem).
It was designed to test whether cauliflower could partially substitute for xanthan as a thickening agent. The samples presented a granular texture, which limited their use except for their incorporation in 'bolognese' type sauces. [96] Pork patties Leaves Dried in a vacuum oven (45 • C, 8 h) Consists of 50 g of califlower leaves ground + 500 mL (80% EtOH). Incorporation: 2.5-10 g/kg by-product extracts, or 0.2 g/kg BHA.

Conclusions and Future Perspectives
Green technologies used to extract the main biocompounds from Brassica by-products and their possible application to fortify new foods have been thoroughly reviewed. The extraction yield depends on the raw material (cv., moisture, part of the plant, etc.), the applied pretreatment (drying technology, particle size, abiotic elicitors such as UV or wounding, etc.), and the key compound to be extracted (fiber, phenolics, isothiocyanates, GLS, etc.). Specific conditions and parameters must be monitored during the extraction process, and their optimization must be studied. Although most of the evidence found is related to USAE and MWAE as the best extraction methods, there are studies suggesting others like, EAE, and novel technologies such as supercritical fluids, ultrafiltration, or pressurized liquids, which may involve a higher cost. Thus, in future studies, energy efficiency/consumption, environmental impact, and predictive models must be included to optimize the phytochemical extraction. As the main conclusion, through the addition of Brassica by-products and their incorporation into new fortified products, it will be possible to revalorize the Brassica losses generated during the first steps of the food production chain, developing new products with potential health benefits while reducing their environmental impact within a circular economy framework.