Prerpints.org logo
Preprint
Review

Potential of Deep Eutectic Solvents in the Extraction of Organic Compounds From Food Industry By-Products and Agro-Industrial Waste

Altmetrics

Downloads

345

Views

69

Comments

0

A peer-reviewed article of this preprint also exists.

Submitted:

29 December 2023

Posted:

03 January 2024

You are already at the latest version

Alerts
Abstract
Global food waste has a huge impact on the environment, as it is a source of greenhouse gas (GHG) emissions and wasted natural resources. Across the world, over 30% of food is lost or wasted each year. Aside from this, food industry, as well, is one of the biggest sources of agro-industrial waste and by-products, which can be valorized and used for different purposes. Such waste is a good source of bioactive organic compounds which can be extracted without al-tering their properties, where deep eutectic solvents (DESs) can serve as green solvents and excel-lent replacement for volatile organic solvents. Isolated compounds can be used in innovative food production, chemical production, cosmetics and other industries. DESs have attracted extraordi-nary attention due to their advantages such as environmental friendliness, availability and easy preparation, easy handling and utilization of non-toxic components for their formation. Due to those properties, they are a greener alternative to classic organic solvents for many processes, in-cluding extractions. In this paper, we review the utilization of deep eutectic solvents as potential green media for the extraction of organic compounds such as polyphenols, carbohydrates, pro-teins, alkaloids from by-products of the food industry and agro-industrial-waste.
Keywords: 
Subject: Chemistry and Materials Science  -   Applied Chemistry

1. Introduction

According to research conducted within the FUSIONS4 project [1] of the European Commission, about 88 million tons of food are thrown away in the EU member states annually. In EU member states, the amount of discarded food (edible and inedible) amounts to 173 kilograms per inhabitant. The total amount of food produced in the EU in 2011 was approx 865 kg/inhabitant, which would mean that 20% of the total produced food is wasted. Furthermore, food industry generates huge amounts of waste and by-products, which is usually discarded, making a huge load to the environment. Those by-products are usually rich in different benefitial compounds that can be isolated and used for different purposes [2,3].
Waste management is a complex and expensive process and has a harmful impact on the environment. Therefore, there is a need to develop a method to utilize the potential of by-products for conversion into bioactive organic compounds. Valorization can reduce or eliminate environmental pollution and achieve sustainable growth by creating value-added outcomes from new bioresources. The aim of this paper is to present new trends in solving the problem of food industry waste and agro-waste obtained from the processing of mostly plant raw materials. This is an area of research of exceptional importance since by-products such as bark, seeds and pulp are good sources of various bioactive organic compounds that can be used as functional ingredients or nutraceuticals in food production, cosmetics or in the pharmaceutical industry. Bioactive substances that are most often isolated from by-products are polyphenols, proteins, organic acids, alkaloids, carotenoids, sugars, lipids, etc. Many of these compounds possess multiple health benefits such as antitumor [4,5], antioxidant [6,7,8], antihypertensive [9,10], antimicrobial [11], hypoglycemic [12], antiviral [13,14] and others.
Conventional organic solvents such methanol, acetone, ethyl acetate, benzene, chloroform, dichloromethane, toluene, petroleum ether, and hexane are commonly used in extraction of the above-mentioned compounds from different byproducts. These solvents often show high vapour pressure and are usually harmful, flammable, as well as not environmentally friendly. Capello et al. [15] proposed a substitution of such solvents with green solvents, describing the characteristics, which green solvents should possess. The first is to replace hazardous organic solvents with less hazardous ones that have less impact on the environment, human health and safety, possess greater biodegradability or reduced ozone depletion potential. Another is to use biosolvents as ethanol, produced from renewable sources. The third is the use of supercritical fluids, which are harmless to the environment, and the fourth is use of ionic liquids with low vapour pressure, and thus less emission to air. Ionic liquids, solvents formed from organic cations and anions, do possess some advantages to conventional VOSs (volatile organic solvents), such as high thermal stability, non-volatility, but many of them showed toxic effects towards different organisms [16]. Very similar, but yet structurally different solvents have arisen in the last decade, showing some advantages over ILs, along with great potential for different processes, called deep eutectic solvents (DESs). DESs have attracted extraordinary attention due to their advantages such as environmental friendliness, good electrical conductivity, stability, low cost and easy preparation. They were first mentioned by Abbott et al. in 2003 [17], and numerous scientific reports have been published to date [18,19,20,21,22]. The extraction of various value-added bioactive compounds is of utmost importance using DESs because of their efficient analytic potential and low toxicity unlike the organic solvents [23].

2. Deep eutectic solvents

Since their first introduction in literature in 2003 by Abbot et al. [17], deep eutectic solvents have become a subject of many researchers. Abbot et al. (2003) [17] were investigating choline chloride and urea mixtures when they noticed a large melting point depression of the mixtures compared to the melting points of the pure components. Due to large melting point depression, such solvents were designated as „deep“ eutectic solvents. Later, some authors suggested that a different definition of deep eutectic solvents is needed, and that their melting point should not be compared to the pure components, but to one of their ideal liquid mixture [24]. Therefore, Martins et al. designated them as: „a mixture of two or more pure compounds for which the eutectic point temperature is below that of an ideal liquid mixture, presenting significant negative deviations from ideality“ [24]. Due to their interesting properties, DESs have found their application in many scientific areas. They have been extensively used in extraction of bioactive components from different materials [25,26,27,28,29,30,31], many synthetic procedures [32,33,34,35,36,37,38,39,40], stabilization od bioactive compounds [41,42,43,44,45], enhancement of drug delivery [46,47,48], pretreatment of food industry waste [49,50,51].
Hansen et al. [18] classified DESs into 5 types: type 1 is formed by the combination of quaternary ammonium salt (QAS) and metal chloride; type 2 of QAS and metal chloride hydrate; type III of QAS and HBD (organic acids, amides or polyoles); type IV of metal salt and HBDs and type 5 consists of a new class of nonionic HBAs and HBDs. Furthermore, some authors classify them according to the nature of their components as NADES, which are formed of purely natural components, THEDES, the ones formed of pharmaceutically active components, TDES, the ones formed from three components, etc. Either way, DESs can be prepared by heating the mixture of desired components until the formaton of clear liquid, evaporation of water from the solution of desired components, freeze-drying or simply by grinding the components [18]. Phisycal and chemical properties of DESs are tuneable and can be adjusted for specific use, since different components can be mixed and combined in different ratios [19]. Net of hydrogen bonding, van der Waals interactions or ionic bonding between components causes a charge delocalization thus lowering the lattice energy of the system, consequently decreasing the melting point [18,19,52]. Although DESs show many promising properties, their high viscosity and density are one of their major drawbacks, especially is one is to scale the process up. These are governed by the strenght of intermolecular bonding between DESs’ components [53,54] and can be reduced to some extent by the temperature rise or addition of water. On the other hand, the addition of high amounts of water can weaken the hydrogen bonding between HBAs and HBDs, causing the loss of eutectic properties [55]. Many authors designate them as desirable, compared to volatile organic solvents, as they show low vapour pressure, can be made of natural, non-toxic and biodegradable compounds and are easy to handle [41,52,56]. They have found their wide application since are considered to adhere the green chemistry principles and are thus designated as green solvents.

3. Extractions of organic compounds from fruits by-products

3.1. Bioactive Compounds in Fruit Waste

During the production process as well as after the consumption of food, a large amount of waste biomass is created. Great part of this can be attributed to fruit waste. Fruit wastes are one of the main sources of municipal waste. Rapid economic growth causes greater consumption of different varieties of fruit produced throughout the world. Due to the large-scale industrial processing of fruit, fruit waste such as peel, seeds and other inedible parts of fruit, accumulates. Fruit injuries during food transport and storage are the main contributors to the fruit waste productions. Fruits can be damaged at all stages of handling, during collection, transport, receiving, packaging, storage, as well as during preparation for consumption [57]. For that reason, it should be protected from external factors such as shocks, which cause mechanical damage, as well as internal ones, which can cause water loss. Two fruit waste disposal techniques include landfills and incineration. Inappropriate procedures with disposed waste can result in the emission of methane and CO2, while burning can cause the formation of carcinogenic and toxic organic compounds such as dioxins, furans and acid gases [58]. Many strategies have been developed in recent years for food waste management. For the most part, fruit waste is used as animal feed or fertilizers [59].
Fruit waste is a rich source of extremely valuable bioactive compounds. It provides a reliable source of secondary metabolites for the development of possible food additives, functional foods, preservatives, and nutraceuticals [60]. It contains bioactive phytonutrients that have potential pharmacological properties and show positive effects on human health. Among the pharmacological properties, antioxidant activity stands out. Antioxidants attenuate generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in human, animal and in vitro studies. Antioxidants prevent adversely alterations of lipids, proteins, and DNA. Hence, application of external source of antioxidants can assist in coping this oxidative stress [61,62,63,64].
Citrus fruits, the most produced crops in the world, yield up to 15 million tons of by-products per year through processing in the food industry. All of the citrus fruits belong to the Rutaceae family, which comprises oranges, mandarins, lemons, limes, grapefruit, pomelo, citrons, etc. [65]. By-products of fruit processing are usually seeds, peel, pulp and leaves. It has been proven that they are a rich source of a wide range of bioactive organic compounds such as polyphenols, enzymes, sugars (glucose, fructose, sucrose), polysaccharides (cellulose, starch, pectin, dietary fibers), organic acids (citric, malic, oxalic acids), essential oils (limonene), pigments (carotene, lutein), lipids (linolenic, oleic, palmitic, stearic acids) vitamins (Vitamin C, Vitamin B complexes) and others [66]. Therefore, one of the main goals of the food industry is to reuse and recycle fruit by-products [67].
Apple is the basis of fruit production. Because of the natural apple juice production, usually performed by pressing and squeezing the fruit, apple pomace is generated as the major by-product. Pomace makes up 25-30% of the apple, depending on the variety and the efficiency of processing. Apple pomace itself consists of seeds, seedpods and skin. It is a high-quality source of carbohydrates, pectin, fiber and minerals. It contains polyphenols: phlorizin, catechin, epicatechin, procyanidin B2, hyperin, quercetin, and others. The most important apple minerals are Ca, Na, K, P, and Mg, which play a key role in processes important for human health. It makes it even more important to develop new methods for bioactive compounds extraction from apple by-products and convert it into value-added products with different functionalities. It has been proven that apple pomace extracts possess anticancer, cardioprotective, and antimicrobial biological activities [68,69,70,71].
The grapevine (Vitis vinifera) is another of the most cultivated crops in the world. It is estimated that 80% of the annual production of grapes is processed into wine, with 20-30% of the mass of used grapes (pulp, skin, stems, seeds) remaining as solid bio-waste. The major by-product of the grape wine industry is grape pomace. Grape pomace is mainly used as fertilizer in vineyards, it is burned or dumped unplanned in the fields, which can represent a major ecological problem. It is a good source of flavanols, phenolic acids, and flavonols, and its extracts usually show enhanced antioxidant capacity [72]. Except antioxidant capacity, they possess various health benefits such anticarcinogenic, anti-inflammatory, antimicrobial, cardioprotective and neuroprotective [73].
Berries include chokeberry, raspberries, blackberries, blueberries, currants, cranberries and other berries. Some of them are used to manufacture juice, wine and their processing often results in a significant amount of by-product - pomace. This by-product often represents a valuable nutritional source of bioactive compounds and dietary fibers that could enhance either technological or nutritional properties of foods [74].

3.2. Phenolic compounds

Polyphenols are one of the largest groups of secondary metabolites with antioxidant properties [75,76,77]. They belong to the most important natural antioxidants that have numerous health benefits related to chronic diseases, such as cardiovascular disease, various cancers type [78,79,80]. The application of DESs for extraction of bioactive compounds from different food industry and agro-industrial waste in the past decade has been prominent. Newer techniques can improve the existing extraction mechanism and shorten the extraction time, reduce solvent consumption and reduce process costs. Therefore, techniques such as microwave [81], ultrasound [82,83], pulsed electric field (PEF) [84], and high-voltage electric discharge (HVED) [85] have already been combined with DESs to improve the extraction yield of polyphenols.
Mango peels, a by-product of mango processing, may be valorized as an efficient source of antioxidants. The extraction of polyphenols from ripe mango Mangifera indica (L.) peels was carried out using DES (lactic acid/sodium acetate/water, 3:1:4) using microwave-assisted extraction (MAE) technique. The extraction using MAE in combination with DESs showed a significant impact on the production proficiency of phenolic compounds (56.17 mg GAE/g dry weight (DW)) [86].
DESs and aqueous glycerol were used for solid-liquid extraction (SLE) of polyphenols from grapefruit peels. It was reported that DESs or aqueous glycerol is a good green alternative to replace the conventional solvents and enhance the yield of the flavonoid naringin from grapefruit peels [87].
Natural deep eutectic solvents (NADES) showed a satisfactory capacity to extract D-limonene, and excellent capacity to extract polyphenols and proteins from the orange peel [88]. The results of one study showed that DESs combined with ultrasound technology are excellent tools for extraction of anthocynanins and polyphenols from blueberry pomace. Better yields were obtained with DES ChCl:butane-1,4-diol (molar ratio 1:3) at a temperature of 63 °C compared to extraction with 70% ethanol [89].

3.3. Carbohydrates

NADESs were proved to be promising co-solvents and can be used for extracting a wide range of biomaterials, such as polysaccharides. Polysaccharides derived from agro- industrial waste include cellulose, hemicellulose, starch, pectin, fucoidan, carrageenan, chitosan and alginate. These polymers are linked by chemical bonds, such as β-1,4-glycosidic bond, α-1,6- glycosidic bond, α-1,4-glycosidic bond, and intermolecular forces, such as hydrogen bonds and van der Waals forces [90]. Pectins are water-soluble carbohydrates found in cell walls and are built from main monomer D-galacturonic acid and each unit is linked to the other by α-(1,4)-glycosidic bond. Pectin rich extracts are traditionally used in the food industry as an additive for gelling, thickening, swelling and hydration capacity [57]. The richest source of pectins are citrus fruits such as lemon peel [91,92,93], apple pomace [93], mango peel [94], pomegranate peel [95], kiwifruit pomace [96], papaya peel [97], passion fruit peel [98], jackfruit peel [99], sour orange peel [100], and in gape pomace [101]. Cellulose is a linear polysaccharide polymer consisting of D-glucose monosaccharide units linked by β-1,4-glycosidic bonds. Chemical reactions on the hydroxyl groups of cellulose are difficult, and the reason for this is intramolecular and intermolecular hydrogen bonds, which make it impossible to dissolve cellulose in water and most organic solvents [57]. Corn husk and grape stalk [102], pomegranate peel, marc of strawberry-tree fruit [103], chestnut shell [104], banana [105], and orange peel [106] are sources of cellulose. Cellulose as natural, biodegradable, and versatile polymer can be used for variety of food and non-food applications, as well as in pharmaceutical, paper, textile, wood, and industrial chemistry. It is also useful in production of micro and nanocellulose, which are important for polymer composite materials [107].
These carbohydrate polymers have demonstrated anti-tumor, antioxidant, and hypoglycemic functions, making them widely used in medicine, substance growth, and the preparation of chemicals [108,109,110,111].
In various studies, ChCl based eutectic solvents were used for the extraction of pectin from food industry by-products. In one study pectin was extracted from pomelo (Citrus grandis (L.) peels using natural deep eutectic solvents in combination with sonication. The results showed that the best solvents for extraction were choline chloride:malonic acid (ChCl:Mal) and choline chloride:glucose:water (ChCl:Glc:W) NADESs. Pectin was obtained in both NADEs in 94% yield after optimization at 80 °C, with 60 min of sonication, pH < 3.0, and a NADES-to-water ratio of 1:4.5 (v/v) [112]. Another study showed that treatment of apple pomace with eutectic solvents, such as ChCl:lactic acid and ChCl:urea improved the efficiency of pectin extraction. However, some solvents, like ChCl:oxalic acid, were not suitable for pectin extraction, since carbohydrate degradation occurred a lower yield was obtained [113].

3.4. Proteins

The data on the presence and extraction of proteins and amino acids from food industry by-products is limited. The protein content in pomegranate peel was reported to be approximately 3% [114]. However, a higher content was found in pomegranate seeds, reaching about 14% [115]. Regarding amino acid levels, some authors indicated that citrus peel had a high content of proline, asparagine, aspartate, alanine, serine, and arginine [116]. A sustainable methodology based on the use of high voltage electrical discharges (HVED) and DESs for the simultaneous extraction of proteins and polyphenols from pomegranate seeds was developed by Hernandez et al. (2022). Pomegranate seeds were firstly pretreated with HVED and, next, exposed to a solid-liquid extraction (SLE) using DESs. All DESs promoted the extraction of proteins and polyphenols, although the extraction of proteins was further improved, especially with ChCl:Glc, which increased the relative protein content in a 94% which indicate how DESs improved the diffusivity of both proteins and polyphenols [85].

3.5. Other compounds

Fruit peel from food industry by-products are an excellent sources of terpenes. Depending on the number of the isoprene units, they are classified as hemiterpenes (one isoprene unit), monoterpenes (2 unit), sesquiterpenes (3 unit), diterpenes (4 unit), sesterterpenes (5 unit)), triterpenes (6 unit), and tetraterpenes (8 unit). In orange peel were identified D-limonen, linalool, and myrcene, in tomato peel lycopene, in melon peel carotenoids such as β-carotene, zeaxantin, violaxantin and lutein.
Thymol, p-cymene, carvacrol are identified in by-products derived from essential oils distillation of aromatic plants. These compounds are active ingredients in flavoring, perfumery, and aromatherapy [57].
Due to their hydrophobic nature and harmless and renewable character, terpenes and terpenoids have been used in the design of eutectic solvents. Due to their eco-friendly properties, they are proposed as possible substitutes for conventional organic solvents in the separation of organic compounds from aqueous streams [117].
The extraction of vitamin E from red palm biodiesel has been also addressed using eutectic solvents. Manurung et al. (2018) used solvents formed by potassium carbonate and glycerol at salt:glycerol molar ratios of 1:5, 1:6 and 1:7. The highest extraction yields were achieved in the extraction of γ-tocotrienol, δ-tocotrienol and α-tocotrienol from biodiesel using the potassium carbonate + glycerol eutectic solvent with a molar ratio of 1:6 [118].
Deep eutectic solvents in combination with the ultrasonic method were used for delignification of watermelon rind, whereby a maximum lignin removal of 44% was achieved in a sonication time of 40 min at a temperature of 120 °C [119].
Table 1. Extraction of bioactive compounds from fruit waste using various DESs.
Table 1. Extraction of bioactive compounds from fruit waste using various DESs.
Fruits Waste Extraction technique/conditions DESs Bioactive compounds Reference
Polyphenols
Orange peel Solid-liquid extraction (SLE) LA:glucose (GLC) (5:1),
L-proline:malic acid (1:1)		 polyphenols and flavonoids [120]
SLE , 50 oC, 30 min ChCl:citric acid (CA) (1:1) hesperidin [121]
SLE, 45 ±5 oC, 20 min ChCl:malic acid
ChCl:glycerol
 flavonoids [120]
Lemon peel RP-LC–QTOF-MS/MS ChCl:glycerol (1:3) quercetin,
p-coumaric acid)		 [122]
Tangerine peel USE (20 W, 35 kHz) ChCl:levulinic acid:N-methyl urea (1:1.2:0.8) polymethoxylated flavonoids and their glycosides [123]
Grapefruit peel HVED
SLE, 50 °C, 60 min Solid/liquid ratio (1:10)		 LA:Glc (5:1)
 polyphenols
naringin		 [124]
Mango peel MAE Sodium acetate:LA (1:3) mangiferin [86]
Apple
 pomace
 USE, 83.2 W ChCl:glycerol (1:2) quercerin, chlorogenic acid, gallic acid, phloretin, phloridazin and rutin [125]
SLE, 60 °C, 6 h ChCl:ethylene glycol (1:4) procyanidin, chlorogenic acid, epicatehin hydrate, vanillin, phloridzin [126]
Grape
 pomace
 MWE 300W + USE 50 W ChCl:CA (1:2) anthocyanins, gallic acid, catehin and quercetin 3-O-glucoside [127]
anthocyanins (malvidin-3-O-monoglucosid [128]
SLE, rt, 24 h. betain:CA (1:1) malvidin [129]
USE, 100 W betain:Glc (1:1) flavan-3-ols [130]
SLE, HPLE
 ChCl:ethylene glycol:water, ChCl:glycerol:levulinic acid: water, Ethylene glycol:water, glycerol:water
phenolic acids, flavanols, flavonols [131]
skin USE, 59 kHz ChCl:CA (1:2) flavan-3-ols, catechin, epicatechin, protocatechuic acid [132]
Mangosteen peel USE ChCl:LA (1:2) anthocyanins [133]
Pomegranate
 peel
 SLE, 50 oC
USE, 50 oC, 50 W		 LA:ChCl 3:1, Malic acid Sucrose 1:1, Glycerol Glycine 3:1, ChCl:fructose 1.9:1, Glc:Tartaric acid 1:1, Glycerol Urea 1:1, Malic acid:Glc Glycerol 1:1:1, LA: Glycine 3:1
caffeic acid, kaempferol, luteolin, protocatechuic acid, ellagic acid, chlorogenic acid, hydroxybenzoic acid, gallic acid, quercetin [134]
SLE
 ChCl :glycerol (1:11) polyphenols and flavonoids [135]
USE TPC (water content, 29.30%; liquid-to-solid ratio, 53.50 mL/g; ultrasonic power, 238.20 W; extraction time, 29.50 min¸ PC (water content, 25.65%; liquid-to-solid ratio, 44.20 mL/g; ultrasonic power, 120 W; extraction time, 20 min), and EC (water content, 33.13%; liquid-to-solid ratio, 60 mL/g; ultrasonic power, 300 W; extraction time, 20 min) Total polyphenol content (TPC) punicalagin content (PC), an ellagic acid content (EC) [136]
pretreatment with HVED or US,
SLE
 ChCl:CA, ChCl:acetic acid, ChCl:LA, ChCl : glycerol, and ChCl :Glc polyphenols [85]
Jabuticaba pomace USE ChCl:Propyleneglycol 1:2, ChCl:CA 1:1, ChCl:Malic acid 1:1, CA:Glc:Water 1:1:3 CA:Propylene glycol 1:1 Betaine:CA 3:1
 anthocyanins [137]
Blueberry
 pomace
 USE ChCl: LA (1:1) anthocyanins [138]
USE ChCl:oxalic acid (1:1) anthocyanins [139]
USE ChCl:butane-1,4-diol cyanidin-3-O-rutinoside [140]
Cranberry pomace USE ChCl:betaine hydrochloride:levulinic acid (1:1:2) procyanidins and anthocyanins [141]
Strawberry and raspberry waste
 extrudate SLE
 ChCl:glycolic acid:Oxalic acid (1:1.7:0.3) anthocyanins [142]
Black chokeberry pulp (UMAE-EtOH)
solid–liquid ratio of 1:15, 230 W, 367 s, 52 °C		 ChCl: CA (1:1), ChCl: malic acid (1:1), ChCl:LA (1:1), ChCl: Glc (1:1), ChCl: sucrose (1:1), ChCl: glycerol (1:2), ChCl:CA:Glc (1:1:1), ChCl:CA:glycerol (1:1:1)
 cyanidin-3-O-galactoside, cyanidin-3-O-glucoside, cyanidin-3-O-arabinoside, cyanidin-3-O-xyloside, cyanidin-3,5-O-dihexoside, dimer of cyanidin-hexoside [143]
Sour cherry pomace USE, 40 ◦C, 30 min MWE, 90 W three successive cycles of 5 s (15 s of total time) ChCl:Mallic acid cyanidin-3-O-sophoroside cyanidin 3-O-glucosylrutinoside
cyanidin-3-O- rutinoside quercetin-3-O-glucoside quercetin-3-O-rutinoside quercetin-O-glycoside Isorhamnetin-3-O-rutinoside
 [144]
Carbohydrates
Pomelo peel USE, 80 °C, 60 min, liquid:solid ratio (40:1) ChCl:Mal acid ChCl:Glc:Water pectin [112]
Apple pomace ChCl: LA, ChCl: oxalic acid, ChCl: urea, 1:2 pectin [113]
Banana puree MWE, 25 ◦C, 30 min, water content: 30%, Malic Acid:β-alanine:water (1:1:3) soluble sugars [145]
Grape seed USE, 30°C, 10 min, Dodecanoic Acid: Octanoic Acid (1:1) Gsps [146]
Proteins
Pomegranate seed Pressurized liquid extraction (PLE)
and DES extraction		 ChCl:CA,
ChCl:AA,
ChCl:LA,
ChCl:glycerol,
ChCl:glc		 protein [85]
Orange peel 4 °C, 15 min ChCl -based NADES with ethylene glycol protein [88]
Other compounds
Watermelon rind USE ChCl:LA lignin [119]

4. Extraction from vegetables byproduct

Polyphenols

Onion, as one of the most grown cultures around the world, is a source of huge amounts of by-products, especially in the form of onion peel. It can be used as a source of valuable polypehnols, like quercetin, kaempferol, myricetin, as well as other polyphenols [147]. In order to apply a green extraction of such compounds, Pal and Jadeja (2019) used DESs for polyphenol extraction and comapred it to conventional methods, such as Soxhlet (with methanol) and microwave extraction (with distilled water). They found that choline chloride:urea:water DES can be effectively applied for the above mentioned extraction as a green solvent [147]. Use of NADESs in combination with ultrasound technology also proved the efficacy of these green type of solvents in extraction of quercetin from onion peels [148]. The same research proved the efficacy of NADESs in extraction of bioactive polyphenols from broccoli [148], while Cao et al. (2023) also effectively combined the use of NADESs and ultrasound technology to extract neochlorogenic, ferulic, erucic, quinic, chlorogenic and caffeic acid by combiningfrom broccoli leaves. Their extracts also showed greater TPC, antioxidant and antimicrobial activity than the ones obtained by other extraction methods [149].
Curcumionoides, Curcuma longa yellow pigments, as biologically active compounds with various pharmacological proerties, have a high potential for pharmaceutical, food or cosmetic applications. They can be extracted from C. longa rhizomes using NADESs, in higher yields compared to conventional solvents [150]. Another group of colorants, betalains, were extracted from beetroot waste, using NADES both as extracting and stabilizing solvent as well. Results for NADES extraction were comparable to those of conventional water extraction, while stabilization of betalaines was much higher than in water extracts [151]. Carotenoides are an important group of pigments, with significant biological activity. Tomatoes most significant carotenoid is lycopene, while tomato waste generated during production of tomato sauce, juice or paste, is rich in this health-promoting compound. Menthol:hexanoic acid (2:1) DES was found to be very effective in lycopene extraction compared to conventional solvents [152].
Potato peel is another example of the usual waste containing high amounts of bioactive compounds, like quercetin, chlorogenic acid, caffeic acid, α-solanine and α-chaconine [153]. Polyphenol and bioctive components content varies depending on variety and location, but it can go up to 20 mg/g of the peel [154]. An excellent source of polyphenols is black carrot waste as well. This vegetable is very popular in Turkey, where large amounts of waste are generated due to the production of beverage called Shalgam juice. This waste, in form of fermented black carrot, is rich in polyphenols, which can be effectively extracted using NADESs. According to Toprak and Unlu, ChCl:glycerol was very efficient in TPC extraction, while ChCl:fructose:water and ChCl:sucrose:water were very efficient in total flavonoids and total monomeric antocyanins extraction [155].
Farajzadeh et al. (2018) found a new application of DESs, when they investigated the extraction of pesticides from different friut juice and vegetables, finding that this approach is effective for fast and green analysis of these analytes [156].
Many authors also investigated the removal of lignin from different agro-industrial wastes to facilitate cellulose hydrolysis using green methodologies. Ternary DES (TDES) were succesfully utilized in this manner, both for pretreatment of onion roots and garlic skin, which increased the cellulose content in both cases [157].
Table 2. Extraction of bioactive compounds from vegetable waste using various DESs.
Table 2. Extraction of bioactive compounds from vegetable waste using various DESs.
Vegetable Waste Extraction technique DESs bioactive compounds Reference
Polyphenols
onion peel 60 °C, 120 min, 20:1 (liquid:solid) ChCl:U:H2O (1:2:4) TPC, quercetin, kaempferol, myricetin [147]
Black carrot waste Ultrasonic bath, 50 °C, 30 min, 37 kHz, 140 W ChCl:glycerol (1:2) Polyphenols [155]
Onion 20 °C, 35 min, 400 µL of DES Methanol solution of betaine:d -mannitol Quercetin, isorhamnetin, kaempferol [148]
Curcuma longa rhizomes 50 °C, 0.1:10 g/mL (solid:liquid), 30 min 1:1 citric acid:glucose (1:1), 15 % water Pigments: curcuminoides [150]
Broccoli 20 °C, 35 min, 400 µL of DES Methanol solution of betaine:d -mannitol Quercetin, isorhamnetin, kaempferol [148]
Broccoli leaves Solvent:solid 36.35 mL/g, 49.5 °C, 31.4 min, ultrasonic power 383 W ChCl:1,2-propylene glycol (1:2) neochlorogenic acid, ferulic acid, erucic acid, quinic acid, chlorogenic acid, caffeic acid [149]
Tomato By-products Solvent:solid 25:1, 90 min, 50 °C Menthol:hexanoic acid (2:1) carotenoides [152]
Other
Beet, cucumber, potato, and tomato 70 °C, 5 min, 142 µL DES, 1610 xg 5min centrifugation ChCl:p-chlorophenol Pesticides: diazinon, metalaxyl, bromopropylate, oxadiazon,
fenazaquin		 [156]
Garlic skin ultrasound 20+28+40 kHz, 30 min, r.t., followed by microwave 20 min, 80 °C ChCl:Glycerin:AlCl3·6H2O (1:2:0.2) Removal of lignin [157]
Beetroot Peel and pulp 1:30 g/mL (solid:liquid), 25 °C, ultrasonic bath, 3h, agitation 900 s MgCl2x6H2O:urea (2:1) Betalains [151]
Onion root ultrasound 20+28+40 kHz, 30 min, r.t., followed by microwave 20 min, 80 °C ChCl:Glycerin:AlCl3·6H2O (1:2:0.2) Removal of lignin [157]

5. Extraction from oilseed agro waste

Oilseeds crops are one of the major high-value agricultural commodities. Oils are organic compounds with a major role in the construction of living beings. According to their chemical composition, they are esters of glycerol and higher fatty acids, so they are classified as triglycerides, and they also belong in a wider group of compounds called lipids. For their production, the oilseeds have to be cleaned before refining processes and there should be effective refining steps including cleaning of seeds, mechanical expression, solvent extraction, degumming, neutralization, bleaching, and deodorization. These processes give good quality oil, but a huge quantity of by-products. Disposal of these by-products leads to environmental pollution and causes many other problems. Therefore, it is necessary to develop methods that will enable reuse and exploitation the by-products like husk, hull, cake, pomace or meal, gum, soap stock, spent bleach earth/clay, and distillate [158]. By-products obtained from olive wood and olive oil extraction are known as "olive by-products". A large number of by-products and residues obtained from olive (Olea europaea) harvesting industries have been preserved over the years, and had no practical application for a long time. More recently, it has been confirmed that residual mass is a favorable source of energy and chemicals. Olive pomace is one of the two byproducts of olive oil production. It consists of pits, skins and pulp of olives and contains 35–40 % of the total weight of olives. The most important ingredients of olive pomace are oil, water, proteins and polyphenols. Composition of olive pomace, apart from the variety of olive, it also depends on the method of production of virgin olive oil. If oil is obtained by pressing on hydraulic presses, olive pomace has a low oil content and vegetable water. Recently, olives, virgin olive oil and pomace have attracted a great interest among scientists due to their valuable compounds with health promoting benefits [159,160]. Their benefits mainly arise from the positive bioactive properties of their phenolic compounds (phenolic acids and alcohols, secoiridoid derivatives, lignans and flavones) which have been proved antiviral, antimicrobial, antioxidant, anti-inflammatory and anti-carcinogenic activities [161,162]. As bioactive phenolic compounds are important due to their potential applications in the pharmaceutical, food and nutraceutical industries, they have attracted much attention. Conventional procedures that were used in the past, require a long extraction time and usually a large amount of solvent [163,164]. Today green solvents, with alternative innovative extraction assisted methods using homogenization (HAE), microwaves (MAE), ultrasounds (UAE) and high hydrostatic pressure (HHPAE) has proven to be an efficient media for the extraction of phenolic compounds from olive pomace. The organic acid-based NADESs, ChCl:citric acid and choline chloride:lactic acid, were selected as most promising solvents and proved to be more effective in the extraction of olive pomace phenolic compounds compared to conventional solvent. ChCl:citric acid possessed the highest total phenolic content and antioxidant activity of all the extracts obtained by HAE at 60 °C /12000 rpm and by UAE at 60 °C. Additionally, the choline chloride:lactic acid was found to be the best NADES for the MAE at 60 °C and for HHPAE at 600 MPa/10 min in terms of TPC and antioxidant activity of the obtained extracts. Moreover, HAE was the best method with a better extraction efficiency than that of the MAE, HHPAE and UAE. HPLC phenolic profiles of extracts revealed that NADESs were superior extraction solvents for a wide range of compounds compared to aqueous ethanol or water. If NADES is combined with novel extraction assisted methods (HAE, MAE, UAE, HHPAE), high extraction efficiencies can be achieved in significantly reduced time. The results confirmed that the proposed combined methods could provide an excellent alternative for sustainable and green extraction of phenolic compounds from plant sources leading to novel industrial applications [165].
The term "olive leaf" describes a mixture of leaves and twigs preserved during the pruning of the olive trees and the cleaning and picking of the olives and contains for up to 10% of the total weight of the olives at olive-oil mills. The olive leaf has been postulated as a good source of natural bioactive compounds such as polyphenols, secoiridoids, phenylethanoids and other with many positive effects as antihypertensive, anticarcinogenic, anti-inflammatory, hypoglycemic, antimicrobial, antiviral, anti-tumor, antithrombotic and hypocholesterolemic [166,167,168,169,170,171]. A new methodology was developed for the extraction of phenolic compounds from olive leaves, which includes microwave assisted extraction techniques MAE in DESs. Of the nine tested DESs for the extraction of phenolic compounds, choline chloride ethylene glycol (1:2) proved to be the most effective. The optimal extraction conditions were: temperature 79.6 °C, 43.3% water and 16.7 min of irradiation time. The results of this research indicate the possibility of recovering value compounds for olive leaves, which means that MAE is a green extraction technique in accordance with the principles of green chemistry due to minimal amount of reagents, lower waste generation and the eco-friendly properties of DESs, their low flammability and negligible vapor pressure [172].

6. Extractions from animal byproducts

The largest part of animal waste originates from the meat industry during slaughtering like bones, tendons, skin, contents of the gastro-intestinal tract, blood, and internal organs. Most animal by-products are bioactive peptides that have been intensively researched recently [173]. Blood and collagen are an abundant source of protein and are present up to 4% of total animal weight [174]. Collagen is the main constituent of skin, hide, bones, and cartilage, and its nutritional value is very low, because it lacks essential amino acids. The cheapest way to generate bioactive peptides from collagen is through hydrolysis by microorganisms. Research has shown that peptides exhibit different biological properties such as AChE-inhibition [175], antimicrobial [176,177] or antioxidant [178].
NADES showed potential for application in industry, use in extraction, biocatalysis and electrochemistry [179]. NADES were used in a simple and green analytical method for the extraction of free selenium amino acids in lyophilized milk samples. The optimized extraction of free seleno-amino acids with NADES showed quantitative recoveries with good precision and sensitivity compatible with the SeCys, SeMet and Se-Met-SeCys concentrations in the samples. The method is applicable on real samples such as cow's milk powder samples, freeze-dried selenium-biofortified sheep's milk, and other. Extraction with eutectic solvents is a green method and at the same time a one-step alternative to the traditional solubilization of powdered milk samples [180]. Immunoglobulins (Ig) or antibodies are glycoproteins produced by plasma cells. High selective purification of Ig from quail egg was performed by ultrasound-assisted liquid-liquid microextraction (UA-LLME) in task-specific deep eutectic solvent (TDES). The ability of all glicerol-based eutectic solvents to form aqueous two-phase system (ATPS) with salts of various anionic (K2HPO4, Na2SO4 and Na2CO3) and cationic combinations were explored. Optimization of important parameters with response surface methodology was cultivated and highest yield was achieved for 85% (v/v) of NADES for feed of 18 μg/ml of egg yolk isolate with ultrasound temperature of 35 °C and 12 min contact time respectively [181].
Waste from the fish and seafood industry is a source of many bioactive substances such as omega-3 fatty acids, amino acids, peptides, enzymes, gelatine, collagen, chitin, vitamins, polyphenolic constituents, carotenoids etc. It can also serve as a favorable material for the production of biodiesel. Depending on the structural and functional characteristics, bioactive compounds from fish waste as well as from seafood waste have potential applications in the food industry, pharmaceutical industry, medicine and agriculture [182].
New studies have shown that NADESs based terpenes are an alternative extraction medium for the recovery of astaxanthin (AXT) from waste biomass from shrimp shells, mussels, Heamatococcus pluvialis shells and from other biomasses. The results show that the extraction in NADESs based terpenes at 60 °C in a time of 2 hours gives yields similar to the Soxhlet extraction of 6 hours with acetone as a solvent. With the application of NADES, AXT yields were increased up to 657 times. Research has shown that terpene-based NADES extracts have the potential to inhibit colon cancer cells and affect the negative growth of Gram-positive and Gram-negative bacteria. Of the tested NADES, menthol: myristic acid (8:1) proved to be the most effective solvent. The authors state that such extractscould be used as functional ingredients and natural preservatives in the pharmaceutical, food or cosmetic industries [183].
Fish scales (FS) are waste obtained in the fish processing industry. About 1 million tons of FS are produced every year [184]. FS are a rich source of biocompatible hydroxyapatite (HAp) and also contain proteins collagen and keratin, a small proportion of fat, and vitamins. HAp is increasingly used in the food industry for adsorption of heavy metals in food. Therefore, the use of waste from FS not only reduces the amount of produced waste but also uses it for the development of a new method for increasing the value of the waste. The research results showed that DES choline chloride:glycerol (1:2) is the optimal solvent for extraction. Under optimal conditions (extraction temperature 70 °C, solid:liquid ratio 1:15 g/g and extraction time 2.5 hours) a HAp yield of 47.67%±1.84% was obtained. The analysis of the chemical composition of HAp determined an irregular morphology and a high Ca/P ratio. However, research has shown that the authors have developed a new, environmentally friendly method of HAp recovery from FS [185].
In one study, a green and facile method based on NEDES choline chloride-malic acid, was developed for extracting chitin from shrimp shells. Chitin is linear polysaccharide composed of β-1,4-glycosidic linked N-acetyl-D-glucosamine units. The high extractability of chitin with the NADES can be attributed to the formation of the hydrogen bond interactions between the NADES and shrimp shell components. Competing hydrogen bond formation between the NADES and carbohydrates cause the breaking of the intramolecular hydrogen bond network, which causes weakening the hydrogen bond interactions in the shrimp shells. As a result, chitin is dissolved in the NADES and separated from the proteins. The research showed that this extraction method based on NADES is a suitable approach for the extraction of chitin from shrimp shells and reveals the potential of application in the extraction of biopolymers from natural sources [186].

7. Extractions from other Agri-Food byproducts

Eutectic solvents were used in protein extraction from bamboo shoots. Bamboo shoots or bamboo sprouts are the edible part of bamboo, of which the two most famous species are Bambusa vulgaris and Phyllostachys edulis. They are used in Asian cuisine in fresh, dried or canned form. Protein yield by extraction using the eutectic solvent choline chloride and levulinic acid under optimal conditions (80 °C, 50 min, HBD:HBA molar ratio of 6, solid:liquid ratio of 30 mg/mL, and water content of 40 % v/v) was 39 mg/g dry weight (DW) for the tender tip of the bamboo shoot (TBS), 15 mg/g dry weight (DW) for the basal bamboo shot (BBS), 9.54 mg/g DW for sheat. Compared to conventional extraction using sodium hydroxide, significantly higher protein yields were obtained with deep eutectic solvents [187].
Eucalyptus (Eucalyptus globulus) plantations provide a large amount of biomass residues such as leaves and branches. The leaves of E. globulus are rich in 1,8-cineole, sesquiterpene, phloroglucinol derivatives, flavonoids, tannins and related polyphenols [188]. Extracts and essential oils are used in pharmaceutical, health, agricultural, cosmetic and food industries and in medicine for the treatment of diseases such as tuberculosis, flu, fungal infections and diabetes. Results showed that intensification of extraction using ultrasounds and microwaves in DESs reduced the extraction time to 90 and 7 min, respectively, while maintaining the quality of the extract. The specific energy consumption is also reduced compared to that of the conventional extraction, and it was 2 and 13 times lower for ultrasound assisted extraction UAE and MAE, respectively. Eucalyptus leaves extracts are a rich source of biologically active polyphenolic compounds, such as sideroxylonal, quercetin 3-O-β-D-glucuronide, eucaglobulin or globulusin, ellagic acid and methylellagic acid pentoside and others [189].
The by-products of forestry, logging, and timber production (leaves, branches, cones, root, wood bark, etc.) are natural source of bioactive compounds. Ginkgo biloba is one of the oldest known trees on earth, whose fossil remains are around 200 million years old. It is a treasure of functional phytochemicals with multimedicinal applications. Several chemical compounds have been isolated from G. biloba with a wide range of therapeutic activities. About 38 different flavonoids have been isolated from Ginkgo biloba leaves [190]. Ginkgo flavonoids are strong antioxidants which act as free radical scavengers. They protect against capillary fragility, in reducing edema caused by tissue injury, have anti-inflammatory properties etc. In Ginko were identified and described new terpenoids, lignans, alkylphenols and alkylphenolic acids, carboxylic acids, proanthocyanidins, polyprenols, polysaccharides and others [191]. Plant extracts have exhibited a variety of pharmacological activities, including antibacterial, antioxidant, anti-inflammatory, antiallergic, and cytotoxic anticancer activities [192,193]. A new method of green extraction of flavonoids based on DESs was developed. Fifty DESs were prepared for the purpose in order to investigate the extraction of Ginkgo flavonoids. Compared to present most efficient extraction solvent (70% ethanol in water), in three DESs, choline chloride:1,3-butanediol (ChCl:B), choline chloride:levulinic acid (ChCl:LA1), and 1,2-propanediol:levulinic acid (P:LA1), higher extraction yields were obtained. The extraction process was optimized and the reaction conditions were: ChCl:LA1 containing 40 % (w/w) water was used as the solvent to extract Ginkgo flavonoids at a solvent:solid ratio of 10:1 (v/w), with stirring at 50 °C and 150 rpm for 15 min. under these optimal conditions, ginkgo flavonoids can be extracted from Ginkgo biloba leaf powder in a yield of 99.87%. Recovery of Ginkgo flavonoids in the DES extraction solution was achieved in 93.7% yield using macroporous resin [190].

5. Conclusions

Concern for the environment and the growing demand for various drugs and biologically active substances have led to an increase in finding new uses for food and agricultural by-products. Since waste is rich in bioactive compounds, it can be called "raw material" and not "waste". This review paper presents the overview of the DESs apllication for valorization of mainly food and agricultural industry waste, in order to obtain products with added value. The use of eutectic solvents as green solvents in the extraction of organic compounds from the by-products of the food industry and agro-waste is in accordance with green chemistry principles. The effectiveness of the eutectic solvent depends on the structure, polarity and other physical and chemical properties of the solvent and the extraction method used. Although the mechanisms underlying the extraction process are still understudied, DES have emerged as a promising green solvent due to their easy preparation, sustainability, low cost, and tunable properties. They are widely used in various extraction processes, especially in treatment of agricultural industrial waste, which is in line with the strategic goals of green sustainable development. Choosing the best solvent remains a challenge for further applications in the extraction of bioactive compounds. DES represent significant opportunities in various extraction processes and reaction systems. Valorization through biotechnological and green approaches helps in the development of bioproducts in a cost-effective and comprehensive way. Therefore, the continuation of such DES research and development could lead to breakthroughs in green sustainable technologies.

Author Contributions

Author Contributions: Conceptualization, M.M.; literature search, M.K. and M.J.K., M.M., D.G.S. and V.B. writing—original draft, preparation, M.M., D.G.S. and V.B.; writing—review and editing, and M.M. supervision. All authors have read and agreed to the published version of the manuscript.

Funding

The work was supported throuht the institutional project Faculty of Food Technology Osijek entitled“Synthesis and Characterization of Coumarin Semicarbazides”, led by Maja Molnar, full professor.

Conflicts of Interest

The authors declare no conflict of interest.

Abbreviation

DES – deep eutectic solvent
QAS - quaternary ammonium salt
HIFU - high intensity ultrasound extraction
HBD – hydrogen bond donor
HBA – hydrogen bond acceptor
NADES – natural deep eutectic solvents
THEDES – therapeutic deep eutectic solvents
TDES – ternary deep eutectic solvents
SLE - solid-liquid extraction
ROS - reactive oxygen species
RNS - reactive nitrogen species
DNA - deoxyribonucleic acid
PEF - pulsed electric field
GAE - gallic acid equivalent
DW - dry weight
ChCl – choline chloride
Glc – glucose
LA – lactic acid
CA – citric acid
Mal – malonic acid
AA – acetic acid
TPC -total polyphenol content
PC - punicalagin content
EC - an ellagic acid content
RP-LC–QTOF-MS/MS - reversed phase ultra-pressure electrospray liquid chromatographic time-of-flight massspectrometric method
USE – ulrasound extraction
HVED - high voltage electrical discharges pre-treatment
MAE – microvawe assisted extraction
HPLE - hot pressurized liquid extraction
UMAE-EtOH - ultrasonic-microwave-assisted ethanol extraction methods solid–liquid
PLE - pressurized liquid extraction
Gsps - grape seed polysaccharides

References

  1. Stenmarck, A.; Jensen, C.; Quested, T.; Moates, G. Estimates of European Food Waste Levels | FAO; Fusion: European Union, 2016.
  2. Socas-Rodríguez, B.; Mendiola, J.A.; Rodríguez-Delgado, M.Á.; Ibáñez, E.; Cifuentes, A. Safety Assessment of Citrus and Olive By-Products Using a Sustainable Methodology Based on Natural Deep Eutectic Solvents. J Chromatogr A 2022, 1669, 462922. [CrossRef]
  3. Ojeda, G.; Vallejos, M.; Sgroppo, S.; Sánchez-Moreno, C.; De Ancos, B. Enhanced Extraction of Phenolic Compounds from Mango By-Products Using Deep Eutectic Solvents. Heliyon 2023, 9, e16912. [CrossRef]
  4. Niedzwiecki, A.; Roomi, M.W.; Kalinovsky, T.; Rath, M. Anticancer Efficacy of Polyphenols and Their Combinations. Nutrients 2016, 8, 552. [CrossRef]
  5. Bolhassani, A.; Khavari, A.; Bathaie, S.Z. Saffron and Natural Carotenoids: Biochemical Activities and Anti-Tumor Effects. Biochim Biophys Acta Rev Cancer 2014, 1845, 20–30. [CrossRef]
  6. Pandey, K.B.; Rizvi, S.I. Plant Polyphenols as Dietary Antioxidants in Human Health and Disease. Oxid Med Cell Longev 2009, 2, 270–278. [CrossRef]
  7. Macáková, K.; Afonso, R.; Saso, L.; Mladěnka, P. The Influence of Alkaloids on Oxidative Stress and Related Signaling Pathways. Free Radic Biol Med 2019, 134, 429–444. [CrossRef]
  8. Stahl, W.; Sies, H. Antioxidant Activity of Carotenoids. Mol Aspects Med 2003, 24, 345–351. [CrossRef]
  9. Hügel, H.M.; Jackson, N.; May, B.; Zhang, A.L.; Xue, C.C. Polyphenol Protection and Treatment of Hypertension. Phytomedicine 2016, 23, 220–231. [CrossRef]
  10. Zhou, Z.; Chen, J.; Cui, Y.; Zhao, R.; Wang, H.; Yu, R.; Jin, T.; Guo, J.; Cong, Y. Antihypertensive Activity of Different Components of Veratrum Alkaloids through Metabonomic Data Analysis. Phytomedicine 2023, 120, 155033. [CrossRef]
  11. Manso, T.; Lores, M.; de Miguel, T. Antimicrobial Activity of Polyphenols and Natural Polyphenolic Extracts on Clinical Isolates. Antibiotics (Basel) 2021, 11, 46. [CrossRef]
  12. Kim, Y.; Keogh, J.B.; Clifton, P.M. Polyphenols and Glycemic Control. Nutrients 2016, 8, 17. [CrossRef]
  13. Chojnacka, K.; Skrzypczak, D.; Izydorczyk, G.; Mikula, K.; Szopa, D.; Witek-Krowiak, A. Antiviral Properties of Polyphenols from Plants. Foods 2021, 10. [CrossRef]
  14. Abookleesh, F.L.; Al-Anzi, B.S.; Ullah, A. Potential Antiviral Action of Alkaloids. Molecules 2022, 27, 903. [CrossRef]
  15. Capello, C.; Fischer, U.; Hungerbuhler, K. What Is a Green Solvent? A Comprehensive Framework for the Environmental Assessment of Solvents. Green Chem 2007, 9, 927-934. [CrossRef]
  16. Flieger, J.; Flieger, M. Ionic Liquids Toxicity—Benefits and Threats. Int J Mol Sci 2020, 21, 6267. [CrossRef]
  17. Abbott, A.P.; Capper, G.; Davies, D.L.; Rasheed, R.K.; Tambyrajah, V. Novel Solvent Properties of Choline Chloride/Urea Mixtures. Chem Commun 2003, 2003, 70–71. [CrossRef]
  18. Hansen, B.B.; Spittle, S.; Chen, B.; Poe, D.; Zhang, Y.; Klein, J.M.; Horton, A.; Adhikari, L.; Zelovich, T.; Doherty, B.W.; et al. Deep Eutectic Solvents: A Review of Fundamentals and Applications. Chem Rev 2020, 121, 1232–1285, doi:doi.org/10.1021/acs.chemrev.0c00385.
  19. Smith, E.L.; Abbott, A.P.; Ryder, K.S. Deep Eutectic Solvents (DESs) and Their Applications. Chem Rev 2014, 114, 11060–11082. [CrossRef]
  20. El Achkar, T.; Fourmentin, S.; Greige-Gerges, H. Deep Eutectic Solvents: An Overview on Their Interactions with Water and Biochemical Compounds. J Mol Liq 2019, 288, 111028. [CrossRef]
  21. El Achkar, T.; Greige-Gerges, H.; Fourmentin, S. Basics and Properties of Deep Eutectic Solvents: A Review. Environ Chem Lett 2021, 19, 3397–3408. [CrossRef]
  22. Lomba, L.; Ribate, M.P.; Sangüesa, E.; Concha, J.; Garralaga, M.a P.; Errazquin, D.; García, C.B.; Giner, B. Deep Eutectic Solvents: Are They Safe? Appl Sci 2021, 11, 10061. [CrossRef]
  23. Pacheco-Fernández, I.; Pino, V. Green Solvents in Analytical Chemistry. Curr Opin Green Sustain Chem 2019, 18, 42–50. [CrossRef]
  24. Martins, M.A.R.; Pinho, S.; Coutinho, J.A.P. Insights into the Nature of Eutectic and Deep Eutectic Mixtures. J Solution Chem 2018, 48, 962-982. [CrossRef]
  25. Duan, L.; Dou, L.-L.; Guo, L.; Li, P.; Liu, E.-H. Comprehensive Evaluation of Deep Eutectic Solvents in Extraction of Bioactive Natural Products. ACS Sustainable Chem Eng 2016, 4, 2405–2411. [CrossRef]
  26. Bowen, H.; Durrani, R.; Delavault, A.; Durand, E.; Chenyu, J.; Yiyang, L.; Lili, S.; Jian, S.; Weiwei, H.; Fei, G. Application of Deep Eutectic Solvents in Protein Extraction and Purification. Front Chem 2022, 10, 912411. [CrossRef]
  27. Grozdanova, T.; Trusheva, B.; Alipieva, K.; Popova, M.; Dimitrova, L.; Najdenski, H.; Zaharieva, M.M.; Ilieva, Y.; Vasileva, B.; Miloshev, G.; et al. Extracts of Medicinal Plants with Natural Deep Eutectic Solvents: Enhanced Antimicrobial Activity and Low Genotoxicity. BMC Chemistry 2020, 14, 73. [CrossRef]
  28. Rodríguez-Martínez, B.; Ferreira-Santos, P.; Alfonso, I.M.; Martínez, S.; Genisheva, Z.; Gullón, B. Deep Eutectic Solvents as a Green Tool for the Extraction of Bioactive Phenolic Compounds from Avocado Peels. Molecules 2022, 27, 6646. [CrossRef]
  29. Karimi, S.; Shekaari, H. Application of Acidic Deep Eutectic Solvents in Green Extraction of 5-Hydroxymethylfurfural. Sci Rep 2022, 12, 13113. [CrossRef]
  30. Pal, C.B.T.; Jadeja, G.C. Deep Eutectic Solvent-Based Extraction of Polyphenolic Antioxidants from Onion (Allium Cepa L.) Peel. J Sci Food Agric 2019, 99, 1969–1979. [CrossRef]
  31. Ojeda, G.A.; Vallejos, M.M.; Sgroppo, S.C.; Sánchez-Moreno, C.; de Ancos, B. Enhanced Extraction of Phenolic Compounds from Mango By-Products Using Deep Eutectic Solvents. Heliyon 2023, 9, e16912. [CrossRef]
  32. Lobo, H.R.; Singh, B.S.; Shankarling, G.S. Bio-Compatible Eutectic Mixture for Multi-Component Synthesis: A Valuable Acidic Catalyst for Synthesis of Novel 2,3-Dihydroquinazolin-4(1H)-One Derivatives. Catal Commun 2012, 27, 179–183. [CrossRef]
  33. Perrone, S.; Capua, M.; Messa, F.; Salomone, A.; Troisi, L. Green Synthesis of 2-Pyrazinones in Deep Eutectic Solvents: From α-Chloro Oximes to Peptidomimetic Scaffolds. Tetrahedron 2017, 73, 6193–6198. [CrossRef]
  34. Perrone, S.; Messa, F.; Troisi, L.; Salomone, A. N-, O- and S-Heterocycles Synthesis in Deep Eutectic Solvents. Molecules 2023, 28, 3459. [CrossRef]
  35. Azizi, N.; Edrisi, M. Deep Eutectic Solvent Catalyzed Eco-Friendly Synthesis of Imines and Hydrobenzamides. Monatsh Chem 2015, 146, 1695–1698. [CrossRef]
  36. Ali, S.; Al-Rashida, M.; Younus, H.A.; Moin, S.T.; Hameed, A. Piperidinium-Based Deep Eutectic Solvents: Efficient and Sustainable Eco-Friendly Medium for One-Pot N-Heterocycles Synthesis. ChemistrySelect 2020, 5, 12697–12703. [CrossRef]
  37. Komar, M.; Molnar, M.; Konjarević, A. Screening of Natural Deep Eutectic Solvents for Green Synthesis of 2-Methyl-3-Substituted Quinazolinones and Microwave-Assisted Synthesis of 3-Aryl Quinazolinones in Ethanol. Craot Chem Acta 2019, 92, 511–517. [CrossRef]
  38. Molnar, M.; Komar, M.; Brahmbhatt, H.; Babić, J.; Jokić, S.; Rastija, V. Deep Eutectic Solvents as Convenient Media for Synthesis of Novel Coumarinyl Schiff Bases and Their QSAR Studies. Molecules 2017, 22, 1482. [CrossRef]
  39. Cicco, L.; Vitale, P.; Perna, F.M.; Capriati, V.; García-Álvarez, J. Cu-Catalysed Chan–Evans–Lam Reaction Meets Deep Eutectic Solvents: Efficient and Selective C–N Bond Formation under Aerobic Conditions at Room Temperature. RSC Sustain. 2023, 1, 847–852. [CrossRef]
  40. Balaji, R.; Ilangeswaran, D. Choline Chloride – Urea Deep Eutectic Solvent an Efficient Media for the Preparation of Metal Nanoparticles. J Indian Chem Soc 2022, 99, 100446. [CrossRef]
  41. Dai, Y.; Verpoorte, R.; Choi, Y.H. Natural Deep Eutectic Solvents Providing Enhanced Stability of Natural Colorants from Safflower (Carthamus Tinctorius). Food Chem 2014, 159, 116–121. [CrossRef]
  42. Kalyniukova, A.; Holuša, J.; Musiolek, D.; Sedlakova-Kadukova, J.; Płotka-Wasylka, J.; Andruch, V. Application of Deep Eutectic Solvents for Separation and Determination of Bioactive Compounds in Medicinal Plants. Ind. Crops Prod 2021, 172, 114047. [CrossRef]
  43. Yadav, N.; Venkatesu, P. Current Understanding and Insights towards Protein Stabilization and Activation in Deep Eutectic Solvents as Sustainable Solvent Media. Phys Chem Chem Phys 2022, 24, 13474–13509. [CrossRef]
  44. Elgharbawy, A.A. Shedding Light on Lipase Stability in Natural Deep Eutectic Solvents. Chem Biochem Eng Q  2018, 32, 359–370. [CrossRef]
  45. Xu, P.; Zheng, G.-W.; Zong, M.-H.; Li, N.; Lou, W.-Y. Recent Progress on Deep Eutectic Solvents in Biocatalysis. Bioresour Bioprocess 2017, 4, 34. [CrossRef]
  46. Zainal-Abidin, M.H.; Hayyan, M.; Ngoh, G.C.; Wong, W.F.; Looi, C.Y. Emerging Frontiers of Deep Eutectic Solvents in Drug Discovery and Drug Delivery Systems. J Control Release 2019, 316, 168–195. [CrossRef]
  47. Stott, P.W.; Williams, A.C.; Barry, B.W. Transdermal Delivery from Eutectic Systems: Enhanced Permeation of a Model Drug, Ibuprofen. J Control Release 1998, 50, 297–308. [CrossRef]
  48. Park, C.-W.; Kim, J.-U.; Rhee, Y.-S.; Oh, T.-O.; Ha, J.-M.; Choi, N.-Y.; Chi, S.-C.; Park, E.-S. Preparation and Valuation of a Topical Solution Containing Eutectic Mixture of Itraconazole and Phenol. Arch Pharm Res 2012, 35, 1935–1943. [CrossRef]
  49. Procentese, A.; Rehmann, L. Fermentable Sugar Production from a Coffee Processing By-Product after Deep Eutectic Solvent Pretreatment. Biores Technol Rep 2018, 4, 174–180. [CrossRef]
  50. Procentese, A.; Johnson, E.; Orr, V.; Garruto Campanile, A.; Wood, J.A.; Marzocchella, A.; Rehmann, L. Deep Eutectic Solvent Pretreatment and Subsequent Saccharification of Corncob. Bioresour Technol 2015, 192, 31–36. [CrossRef]
  51. Procentese, A.; Raganati, F.; Olivieri, G.; Russo, M.E.; Rehmann, L.; Marzocchella, A. Deep Eutectic Solvents Pretreatment of Agro-Industrial Food Waste. Biotechnol Biofuels 2018, 11, 37. [CrossRef]
  52. Alonso, D.A.; Baeza, A.; Chinchilla, R.; Guillena, G.; Pastor, I.M.; Ramón, D.J. Deep Eutectic Solvents: The Organic Reaction Medium of the Century. Eur J Org Chem 2016, 2016, 612–632. [CrossRef]
  53. Khandelwal, S.; Tailor, Y.K.; Kumar, M. Deep Eutectic Solvents (DESs) as Eco-Friendly and Sustainable Solvent/Catalyst Systems in Organic Transformations. J Mol Liq 2016, 215, 345–386. [CrossRef]
  54. Zhang, Q.; Vigier, K.D.O.; Royer, S.; Jérôme, F. Deep Eutectic Solvents: Syntheses, Properties and Applications. Chem Soc Rev 2012, 41, 7108–7146. [CrossRef]
  55. Gabriele, F.; Chiarini, M.; Germani, R.; Tiecco, M.; Spreti, N. Effect of Water Addition on Choline Chloride/Glycol Deep Eutectic Solvents: Characterization of Their Structural and Physicochemical Properties. J Mol Liq 2019, 291, 111301. [CrossRef]
  56. Hayyan, M.; Hashim, M.A.; Hayyan, A.; Al-Saadi, M.A.; AlNashef, I.M.; Mirghani, M.E.S.; Saheed, O.K. Are Deep Eutectic Solvents Benign or Toxic? Chemosphere 2013, 90, 2193–2195. [CrossRef]
  57. Lucarini, M.; Durazzo, A.; Bernini, R.; Campo, M.; Vita, C.; Souto, E.B.; Lombardi-Boccia, G.; Ramadan, M.F.; Santini, A.; Romani, A. Fruit Wastes as a Valuable Source of Value-Added Compounds: A Collaborative Perspective. Molecules 2021, 26, 6338. [CrossRef]
  58. Deng, G.-F.; Shen, C.; Xu, X.-R.; Kuang, R.-D.; Guo, Y.-J.; Zeng, L.-S.; Gao, L.-L.; Lin, X.; Xie, J.-F.; Xia, E.-Q.; et al. Potential of Fruit Wastes as Natural Resources of Bioactive Compounds. Int J Mol Sci 2012, 13, 8308–8323. [CrossRef]
  59. Rudra, S.; Nishad, J.; Jakhar, N.; Kaur, C. Food industry waste: mine of nutraceuticals. Int J Environ Sci Technol 2015, 4, 205-229.
  60. Bhardwaj, K.; Najda, A.; Sharma, R.; Nurzyńska-Wierdak, R.; Dhanjal, D.S.; Sharma, R.; Manickam, S.; Kabra, A.; Kuča, K.; Bhardwaj, P. Fruit and Vegetable Peel-Enriched Functional Foods: Potential Avenues and Health Perspectives. Evid Based Complementary Altern Med 2022, 2022, e8543881. [CrossRef]
  61. Sha, S.P.; Modak, D.; Sarkar, S.; Roy, S.K.; Sah, S.P.; Ghatani, K.; Bhattacharjee, S. Fruit Waste: A Current Perspective for the Sustainable Production of Pharmacological, Nutraceutical, and Bioactive Resources. Front Microbiol 2023, 14, 1260071. [CrossRef]
  62. Ali, T.; Kim, T.; Rehman, S.U.; Khan, M.S.; Amin, F.U.; Khan, M.; Ikram, M.; Kim, M.O. Natural Dietary Supplementation of Anthocyanins via PI3K/Akt/Nrf2/HO-1 Pathways Mitigate Oxidative Stress, Neurodegeneration, and Memory Impairment in a Mouse Model of Alzheimer’s Disease. Mol Neurobiol 2018, 55, 6076–6093. [CrossRef]
  63. Ali, A.; Riaz, S.; Sameen, A.; Naumovski, N.; Iqbal, M.W.; Rehman, A.; Mehany, T.; Zeng, X.-A.; Manzoor, M.F. The Disposition of Bioactive Compounds from Fruit Waste, Their Extraction, and Analysis Using Novel Technologies: A Review. Processes 2022, 10, 2014. [CrossRef]
  64. Shimizu, S.; Matsushita, H.; Morii, Y.; Ohyama, Y.; Morita, N.; Tachibana, R.; Watanabe, K.; Wakatsuki, A. Effect of Anthocyanin-Rich Bilberry Extract on Bone Metabolism in Ovariectomized Rats. Biomed Rep 2018, 8, 198–204. [CrossRef]
  65. Richa, R.; Kohli, D.; Vishwakarma, D.; Mishra, A.; Kabdal, B.; Kothakota, A.; Richa, S.; Sirohi, R.; Kumar, R.; Naik, B. Citrus Fruit: Classification, Value Addition, Nutritional and Medicinal Values, and Relation with Pandemic and Hidden Hunger. J Agric Food Res 2023, 14, 100718. [CrossRef]
  66. Panwar, D.; Panesar, P.S.; Chopra, H.K. Recent Trends on the Valorization Strategies for the Management of Citrus By-Products. Food Rev Int 2021, 37, 91–120. [CrossRef]
  67. Andrade, M.A.; Barbosa, C.H.; Shah, M.A.; Ahmad, N.; Vilarinho, F.; Khwaldia, K.; Silva, A.S.; Ramos, F. Citrus By-Products: Valuable Source of Bioactive Compounds for Food Applications. Antioxidants 2023, 12, 38. [CrossRef]
  68. Moni Bottu, H.; Mero, A.; Husanu, E.; Tavernier, S.; Pomelli, C.S.; Dewaele, A.; Bernaert, N.; Guazzelli, L.; Brennan, L. The Ability of Deep Eutectic Solvent Systems to Extract Bioactive Compounds from Apple Pomace. Food Chem 2022, 386, 132717. [CrossRef]
  69. Rashid, R.; Mohd Wani, S.; Manzoor, S.; Masoodi, F.A.; Masarat Dar, M. Green Extraction of Bioactive Compounds from Apple Pomace by Ultrasound Assisted Natural Deep Eutectic Solvent Extraction: Optimisation, Comparison and Bioactivity. Food Chem 2023, 398, 133871. [CrossRef]
  70. Hu, T.; Wang, W.; Gu, J.; Xia, Z.; Zhang, J.; Wang, B. Research on Apple Object Detection and Localization Method Based on Improved YOLOX and RGB-D Images. Agronomy 2023, 13, 1816. [CrossRef]
  71. Ahmed, D.-N.; Kumar, K.; Kaur, J.; Rizvi, Q.U.E.H.; Rizvi, H.; Jan, S.; Chauhan, D.; Thakur, P.; Kumar, S. Apple Wastes and By-Products Chemistry, Processing, and Utilization. In Handbook of Fruit Wastes and By-Products 2022; pp. 73–86 ISBN 978-0-367-72474-0.
  72. Huamán-Castilla, N.L.; Gajardo-Parra, N.; Pérez-Correa, J.R.; Canales, R.I.; Martínez-Cifuentes, M.; Contreras-Contreras, G.; Mariotti-Celis, M.S. Enhanced Polyphenols Recovery from Grape Pomace: A Comparison of Pressurized and Atmospheric Extractions with Deep Eutectic Solvent Aqueous Mixtures. Antioxidants 2023, 12, 1446. [CrossRef]
  73. Panzella, L.; Moccia, F.; Nasti, R.; Marzorati, S.; Verotta, L.; Napolitano, A. Bioactive Phenolic Compounds From Agri-Food Wastes: An Update on Green and Sustainable Extraction Methodologies. Front Nutr 2020, 7. [CrossRef]
  74. Zhang, X.-J.; Liu, Z.-T.; Chen, X.-Q.; Zhang, T.-T.; Zhang, Y. Deep Eutectic Solvent Combined with Ultrasound Technology: A Promising Integrated Extraction Strategy for Anthocyanins and Polyphenols from Blueberry Pomace. Food Chem 2023, 422, 136224. [CrossRef]
  75. Manzoor, M.F.; Xu, B.; Khan, S.; Shukat, R.; Ahmad, N.; Imran, M.; Rehman, A.; Karrar, E.; Aadil, R.M.; Korma, S.A. Impact of High-Intensity Thermosonication Treatment on Spinach Juice: Bioactive Compounds, Rheological, Microbial, and Enzymatic Activities. Ultrason Sonochem 2021, 78, 105740. [CrossRef]
  76. de Lima Cherubim, D.J.; Buzanello Martins, C.V.; Oliveira Fariña, L.; da Silva de Lucca, R.A. Polyphenols as Natural Antioxidants in Cosmetics Applications. J Cosmet Dermatol 2020, 19, 33–37. [CrossRef]
  77. Manzoor, M.F.; Siddique, R.; Hussain, A.; Ahmad, N.; Rehman, A.; Siddeeg, A.; Alfarga, A.; Alshammari, G.M.; Yahya, M.A. Thermosonication Effect on Bioactive Compounds, Enzymes Activity, Particle Size, Microbial Load, and Sensory Properties of Almond (Prunus Dulcis) Milk. Ultrason Sonochem 2021, 78, 105705. [CrossRef]
  78. Kumar, N.; Daniloski, D.; Pratibha; Neeraj; D’Cunha, N.M.; Naumovski, N.; Petkoska, A.T. Pomegranate Peel Extract – A Natural Bioactive Addition to Novel Active Edible Packaging. Food Res Int 2022, 156, 111378. [CrossRef]
  79. Manzoor, M.F.; Hussain, A.; Tazeddinova, D.; Abylgazinova, A.; Xu, B. Assessing the Nutritional-Value-Based Therapeutic Potentials and Non-Destructive Approaches for Mulberry Fruit Assessment: An Overview. Comput Intell Neurosci 2022, 2022, e6531483. [CrossRef]
  80. Speer, H.; D’Cunha, N.M.; Alexopoulos, N.I.; McKune, A.J.; Naumovski, N. Anthocyanins and Human Health-A Focus on Oxidative Stress, Inflammation and Disease. Antioxidants 2020, 9, 366. [CrossRef]
  81. Tapia-Quirós, P.; Granados, M.; Sentellas, S.; Saurina, J. Microwave-Assisted Extraction with Natural Deep Eutectic Solvents for Polyphenol Recovery from Agrifood Waste: Mature for Scaling-Up? Sci Total Environ 2024, 912, 168716. [CrossRef]
  82. Liu, X.-Y.; Ou, H.; Gregersen, H.; Zuo, J. Deep Eutectic Solvent-Based Ultrasound-Assisted Extraction of Polyphenols from Cosmos Sulphureus. J Appl Res Med Arom Plants 2023, 32, 100444. [CrossRef]
  83. Hong, S.M.; Kamaruddin, A.H.; Nadzir, M.M. Sustainable Ultrasound-Assisted Extraction of Polyphenols from Cinnamomum Cassia Bark Using Hydrophilic Natural Deep Eutectic Solvents. Process Biochem 2023, 132, 323–336. [CrossRef]
  84. Li, J.; Chen, W.; Niu, D.; Wang, R.; Xu, F.-Y.; Chen, B.-R.; Lin, J.-W.; Tang, Z.-S.; Zeng, X.-A. Efficient and Green Strategy Based on Pulsed Electric Field Coupled with Deep Eutectic Solvents for Recovering Flavonoids and Preparing Flavonoid Aglycones from Noni-Processing Wastes. J Cleaner Prod 2022, 368, 133019. [CrossRef]
  85. Hernández-Corroto, E.; Boussetta, N.; Marina, M.; García, M.; Vorobiev, E. High Voltage Electrical Discharges Followed by Deep Eutectic Solvents Extraction for the Valorization of Pomegranate Seeds (Punica Granatum L.). Innov Food Sci Emerg Technol 2022, 79, 103055. [CrossRef]
  86. Pal, C.B.T.; Jadeja, G.C. Microwave-Assisted Extraction for Recovery of Polyphenolic Antioxidants from Ripe Mango (Mangifera Indica L.) Peel Using Lactic Acid/Sodium Acetate Deep Eutectic Mixtures. Food Sci Technol Int 2020, 26, 78–92. [CrossRef]
  87. El Kantar, S.; Rajha, H.N.; Boussetta, N.; Vorobiev, E.; Maroun, R.G.; Louka, N. Green Extraction of Polyphenols from Grapefruit Peels Using High Voltage Electrical Discharges, Deep Eutectic Solvents and Aqueous Glycerol. Food Chem 2019, 295, 165–171. [CrossRef]
  88. Panić, M.; Andlar, M.; Tišma, M.; Rezić, T.; Šibalić, D.; Cvjetko Bubalo, M.; Radojčić Redovniković, I. Natural Deep Eutectic Solvent as a Unique Solvent for Valorisation of Orange Peel Waste by the Integrated Biorefinery Approach. Waste Manag 2021, 120, 340–350. [CrossRef]
  89. Zhang, X.-J.; Liu, Z.-T.; Chen, X.-Q.; Zhang, T.-T.; Zhang, Y. Deep Eutectic Solvent Combined with Ultrasound Technology: A Promising Integrated Extraction Strategy for Anthocyanins and Polyphenols from Blueberry Pomace. Food Chem 2023, 422, 136224. [CrossRef]
  90. Liu, Y.; Gao, L.; Chen, L.; Zhou, W.; Wang, C.; Ma, L. Exploring Carbohydrate Extraction from Biomass Using Deep Eutectic Solvents: Factors and Mechanisms. iScience 2023, 26, 107671. [CrossRef]
  91. Antony, A.; Thottiam, V.; thottiam Vasudevan, R. Comprehensive Review on Ultrasound and Microwave Extraction of Pectin from Agro-Industrial Wastes. Drug Invent Today 2018, 10, 2773–2782.
  92. Martins, L.C.; Monteiro, Ca.C.; Semedo, P.M.; Sá-Correia, I. Valorisation of Pectin-Rich Agro-Industrial Residues by Yeasts: Potential and Challenges. Appl Microbiol Biotechnol 2020, 104, 6527–6547.
  93. Waldbauer, K.; McKinnon, R.; Kopp, B. Apple Pomace as Potential Source of Natural Active Compounds. Planta Med 2017, 83, 994–1010. [CrossRef]
  94. Nagel, A.; Winkler, C.; Carle, Re.; Endress, H.-U. Processes Involving Selective Precipitation for the Recovery of Purified Pectins from Mango Peel. Carbohydr Polym 2017, 174, 1144–1155. [CrossRef]
  95. Moorthy, I.G.; Maran, J.P.; Surya, S.M.@; Naganyashree, S.; Shivamathi, C.S. Response Surface Optimization of Ultrasound Assisted Extraction of Pectin from Pomegranate Peel. Int J Biol Macromol 2015, 72, 1323–1328. [CrossRef]
  96. Yuliarti, O.; Goh, K.K.T.; Matia-Merino, L.; Mawson, J.; Brennan, C. Extraction and Characterisation of Pomace Pectin from Gold Kiwifruit (Actinidia Chinensis). Food Chem 2015, 187, 290–296. [CrossRef]
  97. Zhang, W.; Zeng, G.; Pan, Y.; Chen, W.; Huang, W.; Chen, H.; Li, Y. Properties of Soluble Dietary Fiber-Polysaccharide from Papaya Peel Obtained through Alkaline or Ultrasound-Assisted Alkaline Extraction. Carbohydr Polym 2017, 172, 102–112. [CrossRef]
  98. Viganó, J.; Zabot, G.; Martínez, J. Supercritical Fluid and Pressurized Liquid Extractions of Phytonutrients from Passion Fruit By-Products: Economic Evaluation of Sequential Multi-Stage and Single-Stage Processes. J Supercrit Fluids 2016, 122. [CrossRef]
  99. Xu, S.-Y.; Liu, J.-P.; Huang, X.; Du, L.-P.; Shi, F.-L.; Dong, R.; Huang, X.-T.; Zheng, K.; Liu, Y.; Cheong, K.-L. Ultrasonic-Microwave Assisted Extraction, Characterization and Biological Activity of Pectin from Jackfruit Peel. LWT 2018, 90, 577–582. [CrossRef]
  100. Hosseini, S.S.; Khodaiyan, F.; Kazemi, M.; Najari, Z. Optimization and Characterization of Pectin Extracted from Sour Orange Peel by Ultrasound Assisted Method. Int J Biol Macromol 2019, 125, 621–629. [CrossRef]
  101. Spinei, M.; Oroian, M. Microwave-Assisted Extraction of Pectin from Grape Pomace. Sci Rep 2022, 12, 12722.
  102. Ping, L.; Brosse, N.; Sannigrahi, P.; Ragauskas, A. Evaluation of Grape Stalks as a Bioresource. Ind Crops Prod 2011, 33, 200–204. [CrossRef]
  103. Vallejo, M.; Cordeiro, R.; Dias, P.; Monteiro de Moura, C.S.; Henriques, M.; Seabra, I.; Malça, C.; Morouço, P. Recovery and Evaluation of Cellulose from Agroindustrial Residues of Corn, Grape, Pomegranate, Strawberry-Tree Fruit and Fava. Biores Bioproc 2021, 8. [CrossRef]
  104. Husanu, E.; Mero, A.; Gonzalez, J.; Mezzetta, A. Exploiting Deep Eutectic Solvents and Ionic Liquids for the Valorization of Chestnut Shell Waste. ACS Sust Chem Eng 2020, 8, 18386–18399. [CrossRef]
  105. Lapo, B.; Bou, J.J.; Hoyo, J.; Carrillo, M.; Peña, K.; Tzanov, T.; Sastre, A.M. A Potential Lignocellulosic Biomass Based on Banana Waste for Critical Rare Earths Recovery from Aqueous Solutions. Environ Pollut 2020, 264, 114409. [CrossRef]
  106. Bicu, I.; Mustata, F. Cellulose Extraction from Orange Peel Using Sulfite Digestion Reagents. Biores Technol 2011, 102, 10013–10019. [CrossRef]
  107. Omran, A.A.B.; Mohammed, A.A.B.A.; Sapuan, S.M.; Ilyas, R.A.; Asyraf, M.R.M.; Rahimian Koloor, S.S.; Petrů, M. Micro- and Nanocellulose in Polymer Composite Materials: A Review. Polymers 2021, 13, 231. [CrossRef]
  108. Andreeva, A.P.; Budenkova, E.; Babich, O.; Sukhikh, S.; Dolganyuk, V.; Michaud, P.; Ivanova, S. Influence of Carbohydrate Additives on the Growth Rate of Microalgae Biomass with an Increased Carbohydrate Content. Marine Drugs 2021, 19, 381. [CrossRef]
  109. Lovegrove, A.; Edwards, C.H.; De Noni, I.; Patel, H.; El, S.N.; Grassby, T.; Zielke, C.; Ulmius, M.; Nilsson, L.; Butterworth, P.J.; et al. Role of Polysaccharides in Food, Digestion, and Health. Crit Rev Food Sci Nutr 2017, 57, 237–253. [CrossRef]
  110. Świątek, K.; Gaag, S.; Klier, A.; Kruse, A.; Sauer, J.; Steinbach, D. Acid Hydrolysis of Lignocellulosic Biomass: Sugars and Furfurals Formation. Catalysts 2020, 10, 437. [CrossRef]
  111. Münster, L.; Fojtů, M.; Capáková, Z.; Muchová, M.; Musilová, L.; Vaculovič, T.; Balvan, J.; Kuřitka, I.; Masařík, M.; Vícha, J. Oxidized Polysaccharides for Anticancer-Drug Delivery: What Is the Role of Structure? Carbohydrate Polymers 2021, 257, 117562. [CrossRef]
  112. Elgharbawy, A.; Hayyan, A.; Hayyan, M.; Mirghani, M.; Salleh, H.; Rashid, S.; Ngoh, G.; Shan Qin, L.; Mohd Nor, M.R.; Nor, M.; et al. Natural Deep Eutectic Solvent-Assisted Pectin Extraction from Pomelo Peel Using Sonoreactor: Experimental Optimization Approach. Processes 2019, 7. [CrossRef]
  113. Chen, M.; Lahaye, M. Natural Deep Eutectic Solvents Pretreatment as an Aid for Pectin Extraction from Apple Pomace. Food Hydrocoll 2021, 115, 106601. [CrossRef]
  114. Jalal, H.; Pal, M.A.; Ahmad, S.R.; RAther, M.; Andrabi, M.; Hamdani, S. Physico-Chemical and Functional Properties of Pomegranate Peel and Seed Powder. Pharma Innov J 2018, 7, 1127–1131.
  115. Rowayshed, G.; Emad, A.; Mohamed; Aboulfadl, M. Nutritional and Chemical Evaluation for Pomegranate (Punica Granatum L.) Fruit Peel and Seeds Powders By Products. Middle East J Appl Sci 2013, 3(4), 169-179.
  116. Koochi, Z.H.; Jahromi, K.G.; Kavoosi, G.; Ramezanian, A. Fortification of Chlorella Vulgaris with Citrus Peel Amino Acid for Improvement Biomass and Protein Quality. Biotech Rep 2023, 39, e00806. [CrossRef]
  117. Rodríguez-Llorente, D.; Cañada-Barcala, A.; Álvarez-Torrellas, S.; Águeda, V.I.; García, J.; Larriba, Ma. A Review of the Use of Eutectic Solvents, Terpenes and Terpenoids in Liquid–Liquid Extraction Processes. Processes 2020, 8, 1220. [CrossRef]
  118. Manurung, R.; Hutauruk, G.; Arief, A. Vitamin E Extraction from Red Palm Biodiesel by Using K2CO3 Based Deep Eutectic Solvent with Glycerol as Hydrogen Bond Donor. In Human-Dedicated Sustainable Product and Process Design: Materials, Resources, and Energy AIP Conf. Proc 2018, 1977, p. 020011.
  119. Fakayode, O.A.; Aboagarib, E.A.A.; Yan, D.; Li, M.; Wahia, H.; Mustapha, A.T.; Zhou, C.; Ma, H. Novel Two-Pot Approach Ultrasonication and Deep Eutectic Solvent Pretreatments for Watermelon Rind Delignification: Parametric Screening and Optimization via Response Surface Methodology. Energy 2020, 203, 117872. [CrossRef]
  120. Gómez-Urios, C.; Viñas-Ospino, A.; Puchades-Colera, P.; López-Malo, D.; Frígola, A.; Esteve, M.J.; Blesa, J. Sustainable Development and Storage Stability of Orange By-Products Extract Using Natural Deep Eutectic Solvents. Foods 2022, 11, 2457. [CrossRef]
  121. Jokic, S.; Šafranko, S.; Jakovljević Kovač, M.; Cikoš, A.-M.; Kajić, N.; Kolarević, F.; Babic, J.; Molnar, M. Sustainable Green Procedure for Extraction of Hesperidin from Selected Croatian Mandarin Peels. Processes 2019, 7, 469. [CrossRef]
  122. Kalogiouri, N.; Palaiologou, E.; Papadakis, E.-N.; Makris, D.; Biliaderis, C.; Mourtzinos, I. Insights on the Impact of Deep Eutectic Solvents on the Composition of the Extracts from Lemon (Citrus Limon L.) Peels Analyzed by a Novel RP-LC–QTOF-MS/MS Method. Eur Food Res Technol 2022, 248. [CrossRef]
  123. Xu, M.; Ran, L.; Chen, N.; Fan, X.; Ren, D.; Yi, L. Polarity-Dependent Extraction of Flavonoids from Citrus Peel Waste Using a Tailor-Made Deep Eutectic Solvent. Food Chem 2019, 297, 124970. [CrossRef]
  124. El Kantar, S.; Rajha, H.N.; Boussetta, N.; Vorobiev, E.; Maroun, R.G.; Louka, N. Green Extraction of Polyphenols from Grapefruit Peels Using High Voltage Electrical Discharges, Deep Eutectic Solvents and Aqueous Glycerol. Food Chem 2019, 295, 165–171. [CrossRef]
  125. Rashid, R.; Mohd Wani, S.; Manzoor, S.; Masoodi, F.A.; Masarat Dar, M. Green Extraction of Bioactive Compounds from Apple Pomace by Ultrasound Assisted Natural Deep Eutectic Solvent Extraction: Optimisation, Comparison and Bioactivity. Food Chem 2023, 398, 133871. [CrossRef]
  126. Moni Bottu, H.; Mero, A.; Husanu, E.; Tavernier, S.; Pomelli, C.S.; Dewaele, A.; Bernaert, N.; Guazzelli, L.; Brennan, L. The Ability of Deep Eutectic Solvent Systems to Extract Bioactive Compounds from Apple Pomace. Food Chem 2022, 386, 132717. [CrossRef]
  127. Panić, M.; Radić Stojković, M.; Kraljić, K.; Škevin, D.; Radojcic Redovnikovic, I.; Srček, V.; Radošević, K. Ready-to-Use Green Polyphenolic Extracts from Food by-Products. Food Chem 2019, 283. [CrossRef]
  128. Panić, M.; Gunjević, V.; Cravotto, G.; Radojcic Redovnikovic, I. Enabling Technologies for the Extraction of Grape-Pomace Anthocyanins Using Natural Deep Eutectic Solvents in up-to-Half-Litre Batches Extraction of Grape-Pomace Anthocyanins Using NADES. Food Chem 2019, 300, 125185. [CrossRef]
  129. Punzo, A.; Porru, E.; Silla, A.; Simoni, P.; Galletti, P.; Roda, A.; Tagliavini, E.; Samorì, C.; Caliceti, C. Grape Pomace for Topical Application: Green NaDES Sustainable Extraction, Skin Permeation Studies, Antioxidant and Anti-Inflammatory Activities Characterization in 3D Human Keratinocytes. Biomolecules 2021, 11, 1181. [CrossRef]
  130. Panić, M.; Gunjević, V.; Radošević, K.; Cvjetko Bubalo, M.; Ganić, K.K.; Redovniković, I.R. COSMOtherm as an Effective Tool for Selection of Deep Eutectic Solvents Based Ready-To-Use Extracts from Graševina Grape Pomace. Molecules 2021, 26, 4722. [CrossRef]
  131. Huamán-Castilla, N.L.; Gajardo-Parra, N.; Pérez-Correa, J.R.; Canales, R.I.; Martínez-Cifuentes, M.; Contreras-Contreras, G.; Mariotti-Celis, M.S. Enhanced Polyphenols Recovery from Grape Pomace: A Comparison of Pressurized and Atmospheric Extractions with Deep Eutectic Solvent Aqueous Mixtures. Antioxidants 2023, 12, 1446. [CrossRef]
  132. Dabetić, N.; Todorović, V.; Panić, M.; Radojčić Redovniković, I.; Šobajić, S. Impact of Deep Eutectic Solvents on Extraction of Polyphenols from Grape Seeds and Skin. Appl Sci 2020, 10. [CrossRef]
  133. Plaza, M.; Domínguez-Rodríguez, G.; Sahelices, C.; Marina, M. A Sustainable Approach for Extracting Non-Extractable Phenolic Compounds from Mangosteen Peel Using Ultrasound-Assisted Extraction and Natural Deep Eutectic Solvents. Appl Sci 2021, 11, 5625. [CrossRef]
  134. Rajha, H.; Mhanna, T.; El Kantar, S.; el Khoury, A.; Louka, N.; G, R.; Maroun, R. Innovative Process of Polyphenol Recovery from Pomegranate Peels by Combining Green Deep Eutectic Solvents and a New Infrared Technology. LWT 2019, 111. [CrossRef]
  135. Kyriakidou, A.; Makris, D.P.; Lazaridou, A.; Biliaderis, C.G.; Mourtzinos, I. Physical Properties of Chitosan Films Containing Pomegranate Peel Extracts Obtained by Deep Eutectic Solvents. Foods 2021, 10, 1262. [CrossRef]
  136. Kim, H.J.; Yoon, K.Y. Optimization of Ultrasound-Assisted Deep Eutectic Solvent Extraction of Bioactive Compounds from Pomegranate Peel Using Response Surface Methodology. Food Sci Biotechnol 2023, 32, 1851–1860. [CrossRef]
  137. Benvenutti, L.; Sanchez-Camargo, A. del P.; Zielinski, A.A.F.; Ferreira, S.R.S. NADES as Potential Solvents for Anthocyanin and Pectin Extraction from Myrciaria Cauliflora Fruit By-Product: In Silico and Experimental Approaches for Solvent Selection. J Mol Liq 2020, 315, 113761. [CrossRef]
  138. Grillo, G.; Gunjević, V.; Radošević, K.; Redovniković, I.R.; Cravotto, G. Deep Eutectic Solvents and Nonconventional Technologies for Blueberry-Peel Extraction: Kinetics, Anthocyanin Stability, and Antiproliferative Activity. Antioxidants 2020, 9, 1069. [CrossRef]
  139. Fu, X.; Wang, D.; Belwal, T.; Xie, J.; Xu, Y.; Li, L.; Zou, L.; Zhang, L.; Luo, Z. Natural Deep Eutectic Solvent Enhanced Pulse-Ultrasonication Assisted Extraction as a Multi-Stability Protective and Efficient Green Strategy to Extract Anthocyanin from Blueberry Pomace. LWT 2021, 144, 111220. [CrossRef]
  140. Xue, H.; Tan, J.; Li, Q.; Tang, J.; Cai, X. Ultrasound-Assisted Deep Eutectic Solvent Extraction of Anthocyanins from Blueberry Wine Residues: Optimization, Identification, and HepG2 Antitumor Activity. Molecules 2020, 25, 5456. [CrossRef]
  141. Alrugaibah, M.; Yagiz, Y.; Gu, L. Use Natural Deep Eutectic Solvents as Efficient Green Reagents to Extract Procyanidins and Anthocyanins from Cranberry Pomace and Predictive Modeling by RSM and Artificial Neural Networking. Sep Purif Technol 2021, 255, 117720. [CrossRef]
  142. Vázquez-González, M.; Fernández-Prior, Á.; Bermúdez Oria, A.; Rodríguez-Juan, E.M.; Pérez-Rubio, A.G.; Fernández-Bolaños, J.; Rodríguez-Gutiérrez, G. Utilization of Strawberry and Raspberry Waste for the Extraction of Bioactive Compounds by Deep Eutectic Solvents. LWT 2020, 130, 109645. [CrossRef]
  143. Lin, S.; Meng, X.; Tan, C.; Tong, Y.; Wan, M.; Wang, M.; Zhao, Y.; Deng, H.; Kong, Y.; Ma, Y. Composition and Antioxidant Activity of Anthocyanins from Aronia Melanocarpa Extracted Using an Ultrasonic-Microwave-Assisted Natural Deep Eutectic Solvent Extraction Method. Ultrason Sonochem 2022, 89, 106102. [CrossRef]
  144. Popovic, B.M.; Micic, N.; Potkonjak, A.; Blagojevic, B.; Pavlovic, K.; Milanov, D.; Juric, T. Novel Extraction of Polyphenols from Sour Cherry Pomace Using Natural Deep Eutectic Solvents - Ultrafast Microwave-Assisted NADES Preparation and Extraction. Food Chem 2022, 366, 130562. [CrossRef]
  145. Gómez, A.V.; Tadini, C.C.; Biswas, A.; Buttrum, M.; Kim, S.; Boddu, V.M.; Cheng, H.N. Microwave-Assisted Extraction of Soluble Sugars from Banana Puree with Natural Deep Eutectic Solvents (NADES). LWT 2019, 107, 79–88. [CrossRef]
  146. Chen, X.; Zhang, Q.; Yu, Q.; Chen, L.; Sun, Y.; Wang, Z.; Yuan, Z. Depolymerization of Holocellulose from Chinese Herb Residues by the Mixture of Lignin-Derived Deep Eutectic Solvent with Water. Carbohydrate Polym 2020, 248, 116793. [CrossRef]
  147. Pal, C.B.T.; Jadeja, G.C. Deep Eutectic Solvent-Based Extraction of Polyphenolic Antioxidants from Onion (Allium Cepa L.) Peel. J Sci Food Agric 2019, 99, 1969–1979. [CrossRef]
  148. Dai, Y.; Row, K. Application of Natural Deep Eutectic Solvents in the Extraction of Quercetin from Vegetables. Molecules 2019, 24, 2300. [CrossRef]
  149. Cao, Y.; Song, Z.; Dong, C.; Ni, W.; Xin, K.; Yu, Q.; Han, L. Green Ultrasound-Assisted Natural Deep Eutectic Solvent Extraction of Phenolic Compounds from Waste Broccoli Leaves: Optimization, Identification, Biological Activity, and Structural Characterization. LWT 2023, 190, 115407. [CrossRef]
  150. Liu, Y.; Li, J.; Fu, R.; Zhang, L.; Wang, D.; Wang, S. Enhanced Extraction of Natural Pigments from Curcuma Longa L. Using Natural Deep Eutectic Solvents. Ind Crops Prod 2019, 140, 111620. [CrossRef]
  151. Hernández-Aguirre, O.A.; Muro, C.; Hernández-Acosta, E.; Alvarado, Y.; Díaz-Nava, M. del C. Extraction and Stabilization of Betalains from Beetroot (Beta Vulgaris) Wastes Using Deep Eutectic Solvents. Molecules 2021, 26, 6342. [CrossRef]
  152. Vlachoudi, D.; Chatzimitakos, T.; Athanasiadis, V.; Bozinou, E. Enhanced Extraction of Carotenoids from Tomato Industry Waste Using Menthol/Fatty Acid Deep Eutectic Solvent. Waste 2023, 1, 977–992. [CrossRef]
  153. Friedman, M.; Huang, V.; Quiambao, Q.; Noritake, S.; Liu, J.; Kwon, O.; Chintalapati, S.; Young, J.; Levin, C.E.; Tam, C.; et al. Potato Peels and Their Bioactive Glycoalkaloids and Phenolic Compounds Inhibit the Growth of Pathogenic Trichomonads. J Agric Food Chem 2018, 66, 7942–7947. [CrossRef]
  154. Palos-Hernández, A.; Gutiérrez Fernández, M. Y.; Escuadra Burrieza, J.; Pérez-Iglesias, J.L.; González-Paramás, A.M. Obtaining green extracts rich in phenolic compounds from underexploited food by-products using natural deep eutectic solvents. Opportunities and challenges. Sust Chem Pharm 2022, 29, 100773. [CrossRef]
  155. Toprak, P.; Ünlü, A.E. Screening of Natural Deep Eutectic Solvents for the Recovery of Valuable Phenolics From Waste of Shalgam Juice Process. Turkish J Agric Food Sci Technol 2023, 11, 1784–1790. [CrossRef]
  156. Farajzadeh, M.A.; Shahedi Hojghan, A.; Afshar Mogaddam, M.R. Development of a New Temperature-Controlled Liquid Phase Microextraction Using Deep Eutectic Solvent for Extraction and Preconcentration of Diazinon, Metalaxyl, Bromopropylate, Oxadiazon, and Fenazaquin Pesticides from Fruit Juice and Vegetable Samples Followed by Gas Chromatography-Flame Ionization Detection. J Food Comp Anal 2018, 66, 90–97. [CrossRef]
  157. Ji, Q.; Yu, X.; Yagoub, A.E.-G.A.; Chen, L.; Zhou, C. Efficient Removal of Lignin from Vegetable Wastes by Ultrasonic and Microwave-Assisted Treatment with Ternary Deep Eutectic Solvent. Ind Crops Prod 2020, 149, 112357. [CrossRef]
  158. Thangaraju, S.; Pulivarthi, M.; Venkatachalapathy, N. Waste from Oil-Seed Industry: A Sustainable Approach. In; 2020; pp. 177–190 ISBN 9789811589669.
  159. García, A.; Rodríguez-Juan, E.; Rodríguez-Gutiérrez, G.; Rios, J.J.; Fernández-Bolaños, J. Extraction of Phenolic Compounds from Virgin Olive Oil by Deep Eutectic Solvents (DESs). Food Chem 2016, 197, 554–561. [CrossRef]
  160. Chanioti, S.; Tzia, C. Extraction of Phenolic Compounds from Olive Pomace by Using Natural Deep Eutectic Solvents and Innovative Extraction Techniques. Innov Food Sci Emerg Technol 2018, 48, 228–239. [CrossRef]
  161. Chanioti, S.; Siamandoura, P.; Tzia, C. Evaluation of Extracts Prepared from Olive Oil By-Products Using Microwave-Assisted Enzymatic Extraction: Effect of Encapsulation on the Stability of Final Products. Waste Biomass Valor 2016, 7. [CrossRef]
  162. Fernandez-Bolanos, J.; Rodriguez, G.; Rodríguez Arcos, R.; Guillen, R.; Jiménez, A. Extraction of Interesting Organic Compounds from Olive Oil Waste. Grasas Aceites 2006, 57. [CrossRef]
  163. Yao, X.-H.; Zhang, D.-Y.; Duan, M.-H.; Cui, Q.; Xu, W.-J.; Luo, M.; Li, C.-Y.; Zu, Y.-G.; Fu, Y.-J. Preparation and Determination of Phenolic Compounds from Pyrola Incarnata Fisch. with a Green Polyols Based-Deep Eutectic Solvent. Sep Pur Technol 2015, 149, 116–123. [CrossRef]
  164. Cvjetko Bubalo, M.; Ćurko, N.; Tomašević, M.; Kovačević Ganić, K.; Radojčić Redovniković, I. Green Extraction of Grape Skin Phenolics by Using Deep Eutectic Solvents. Food Chem 2016, 200, 159–166. [CrossRef]
  165. Chanioti, S.; Tzia, C. Optimization of Ultrasound-Assisted Extraction of Oil from Olive Pomace Using Response Surface Technology: Oil Recovery, Unsaponifiable Matter, Total Phenol Content and Antioxidant Activity. LWT - Food Sci Technol 2017, 79, 178–189. [CrossRef]
  166. Barrajón-Catalán, E.; Taamalli, A.; Quirantes-Piné, R.; Roldan-Segura, C.; Arráez-Román, D.; Segura-Carretero, A.; Micol, V.; Zarrouk, M. Differential Metabolomic Analysis of the Potential Antiproliferative Mechanism of Olive Leaf Extract on the JIMT-1 Breast Cancer Cell Line. J Pharm Biomed Anal 2015, 105, 156–162. [CrossRef]
  167. Fu, S.; Arráez-Roman, D.; Segura-Carretero, A.; Menéndez, J.A.; Menéndez-Gutiérrez, M.P.; Micol, V.; Fernández-Gutiérrez, A. Qualitative Screening of Phenolic Compounds in Olive Leaf Extracts by Hyphenated Liquid Chromatography and Preliminary Evaluation of Cytotoxic Activity against Human Breast Cancer Cells. Anal Bioanal Chem 2010, 397, 643–654. [CrossRef]
  168. Lee, O.-H.; Lee, B.-Y. Antioxidant and Antimicrobial Activities of Individual and Combined Phenolics in Olea Europaea Leaf Extract. Bioresour Technol 2010, 101, 3751–3754. [CrossRef]
  169. Micol, V.; Caturla, N.; Pérez-Fons, L.; Más, V.; Pérez, L.; Estepa, A. The Olive Leaf Extract Exhibits Antiviral Activity against Viral Haemorrhagic Septicaemia Rhabdovirus (VHSV). Antiviral Res 2005, 66, 129–136. [CrossRef]
  170. Susalit, E.; Agus, N.; Effendi, I.; Tjandrawinata, R.R.; Nofiarny, D.; Perrinjaquet-Moccetti, T.; Verbruggen, M. Olive (Olea Europaea) Leaf Extract Effective in Patients with Stage-1 Hypertension: Comparison with Captopril. Phytomedicine 2011, 18, 251–258. [CrossRef]
  171. Taamalli, A.; Arráez-Román, D.; Zarrouk, M.; Valverde, J.; Segura-Carretero, A.; Fernández-Gutiérrez, A. The Occurrence and Bioactivity of Polyphenols in Tunisian Olive Products and By-Products: A Review. J Food Sci 2012, 77, R83-92. [CrossRef]
  172. Alanon, M.; Ivanović, M.; Caravaca, A.M.G.; Arráez-Román, D.; Segura Carretero, A. Choline Chloride Derivative-Based Deep Eutectic Liquids as Novel Green Alternative Solvents for Extraction of Phenolic Compounds from Olive Leaf. Arab J Chem 2018, 13. [CrossRef]
  173. Mora, L.; Toldrá-Reig, F.; Prates, J.A.M.; Toldrá, F. Cattle Byproducts. In Byproducts from Agriculture and Fisheries; John Wiley & Sons, Ltd, 2019; pp. 43–55 ISBN 978-1-119-38395-6.
  174. Chang, C.-Y.; Wu, K.-C.; Chiang, S.-H. Antioxidant Properties and Protein Compositions of Porcine Haemoglobin Hydrolysates. Food Chem 2007, 100, 1537–1543. [CrossRef]
  175. Bhat, Z.F.; Kumar, S.; Bhat, H.F. Antihypertensive Peptides of Animal Origin: A Review. Crit Rev Food Sci Nutr 2017, 57, 566–578. [CrossRef]
  176. Nedjar-Arroume, N.; Dubois-Delval, V.; Adje, E.Y.; Traisnel, J.; Krier, F.; Mary, P.; Kouach, M.; Briand, G.; Guillochon, D. Bovine Hemoglobin: An Attractive Source of Antibacterial Peptides. Peptides 2008, 29, 969–977. [CrossRef]
  177. Etxeberria, A.E.; Uranga, J.; Guerrero, P.; De la Caba, K. Development of Active Gelatin Films by Means of Valorisation of Food Processing Waste: A Review. Food Hydrocoll 2017, 68, 192–198. [CrossRef]
  178. Liu, R.; Xing, L.; Fu, Q.; Zhou, G.-H.; Zhang, W.-G. A Review of Antioxidant Peptides Derived from Meat Muscle and By-Products. Antioxidants 2016, 5, 32. [CrossRef]
  179. Liu, Y.; Friesen, J.B.; McAlpine, J.B.; Lankin, D.C.; Chen, S.-N.; Pauli, G.F. Natural Deep Eutectic Solvents: Properties, Applications, and Perspectives. J Nat Prod 2018, 81, 679–690. [CrossRef]
  180. López, R.; D’Amato, R.; Trabalza-Marinucci, M.; Regni, L.; Proetti, P.; Maratta, A.; Cerutti, S.; Pacheco, P. Green and Simple Extraction of Free Seleno-Amino Acids from Powdered and Lyophilized Milk Samples with Natural Deep Eutectic Solvents. Food Chem 2020, 326, 126965. [CrossRef]
  181. Balaraman, H.B.; Rathnasamy, S.K. High Selective Purification of IgY from Quail Egg: Process Design and Quantification of Deep Eutectic Solvent Based Ultrasound Assisted Liquid Phase Microextraction Coupled with Preparative Chromatography. Int J Biol Macromol 2020, 146, 253–262. [CrossRef]
  182. Ozogul, F.; Cagalj, M.; Šimat, V.; Ozogul, Y.; Tkaczewska, J.; Hassoun, A.; Kaddour, A.A.; Kuley, E.; Rathod, N.B.; Phadke, G.G. Recent Developments in Valorisation of Bioactive Ingredients in Discard/Seafood Processing by-Products. Trends Food Sci Technol 2021, 116, 559–582. [CrossRef]
  183. Rodrigues, L.; Pereira, C.; Leonardo, I.; Fernández, N.; Gaspar, F.; Silva, J.; Reis, R.L.; Duarte, A.; Paiva, A.; Matias, A. Terpene-Based Natural Deep Eutectic Systems as Efficient Solvents To Recover Astaxanthin from Brown Crab Shell Residues. ACS Sust Chem Eng 2020, 8. [CrossRef]
  184. Elvevoll, E.O.; James, D. The Emerging Importance of Dietary Lipids, Quantity and Quality, in the Global Disease Burden: The Potential of Aquatic Resources. Nutr Health 2001, 15, 155–167. [CrossRef]
  185. Liu, Y.; Li, J.; Wang, D. Yang, F.; Zhang, L.; Ji, S.; Wang, S. Enhanced Extraction of Hydroxyapatite from Bighead Carp (Aristichthys Nobilis) Scales Using Deep Eutectic Solvent. J Food Sci 2020, 85, 150–156, doi.org:10.1111/1750-3841.14971.
  186. Huang, W.C.; Zhao, D.; Guo, N.; Xue, C.; Mao X. Green and Facile Production of Chitin from Crustacean Shells Using a Natural Deep Eutectic Solvent. J Agric Food Chem 2018, 66, 11897–11901. [CrossRef]
  187. Lin, Z.; Jiao, G.; Zhang, J.; Celli, G.B.; Brooks, M.S.L. Optimization of Protein Extraction from Bamboo Shoots and Processing Wastes Using Deep Eutectic Solvents in a Biorefinery Approach. Biomass Convers Biorefinery 2020, 11, 2763-2774. [CrossRef]
  188. Amakura, Y., Yoshimura, M., Sugimoto, N., Yamazaki, T., Yoshida, T. Marker constituents of the natural antioxidant eucalyptus leaf extract for the evaluation of food additives. Biosci Biotechnol Biochem 2009, 73, 5 1060–51065. [CrossRef]
  189. Gullón, B.; Muñiz-Mouro, A.; Lú-Chau, T.A.; Moreira, M.T.; Lema, J.M.; Eibes, G. Green Approaches for the Extraction of Antioxidants from Eucalyptus Leaves. Ind Crops Prod 2019, 138, 111473. [CrossRef]
  190. Yang, M.; Cao, J.; Cao, F.; Lu, C.; Su, E. Efficient Extraction of Bioactive Flavonoids from Ginkgo Biloba Leaves Using Deep Eutectic Solvent/Water Mixture as Green Media. Chem Biochem Eng Q 2018, 32, 315–324. [CrossRef]
  191. Noor-E-Tabassum; Das, R.; Lami, M.S; Chakraborty, A.J.; Mitra, S.; Tallei, T.E.; Idroes, R.; Mohamed, A.A.R.; Hossain, J.; Dhama, K.; Mostafa-Hedeab, G.; Emran, T.B. Ginkgo biloba: A Treasure of Functional Phytochemicals with Multimedicinal Applications. Evid-Based Complement Alternat Med, 2022, 2022, 8288818. [CrossRef]
  192. Belwal, R.S.R.T.; Giri, L.; Amit, B.; Tariq, M.; Kewlani, P. Ginkgo Biloba. In Nonvitamin and Nonmineral Nutritional Supplements. Editor(s): Nabavi, S.M.; Sanches Silva, A. Academic Press, 2019, 241-250. [CrossRef]
  193. Chan, P.C.; Xia, Q.; Fu, P.P. Ginkgo biloba leave extract: biological, medicinal, and toxicological effects. J Environ Sci Health-Part C: Environ Carcinog Ecotox Rev, 2007, 25, 211-244. [CrossRef]
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.
Copyright: This open access article is published under a Creative Commons CC BY 4.0 license, which permit the free download, distribution, and reuse, provided that the author and preprint are cited in any reuse.
Prerpints.org logo

Preprints.org is a free preprint server supported by MDPI in Basel, Switzerland.

facebook logotwitter logolinkedin logo
MDPI Initiatives
Important Links
Subscribe

Disclaimer

Terms of Use

Privacy Policy

© 2024 MDPI (Basel, Switzerland) unless otherwise stated