Next Article in Journal
Research Progress of Bioactive Peptides in Improving Type II Diabetes
Previous Article in Journal
The Origin Link Between “Śląski” Cheese and the Silesia Region: A Basis for Obtaining Protection for Geographical Indications
Previous Article in Special Issue
Increasing the Content of Bioactive Compounds in Apple Juice Through Direct Ultrasound-Assisted Extraction from Bilberry Pomace
 
 
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Review

Extraction of Biomolecules from Coffee and Cocoa Agroindustry Byproducts Using Alternative Solvents

by
José Pedro Zanetti Prado
1,
Rodrigo Corrêa Basso
2 and
Christianne Elisabete da Costa Rodrigues
1,*
1
Laboratório de Engenharia de Separações (LES), Departamento de Engenharia de Alimentos (ZEA), Faculdade de Zootecnia e Engenharia de Alimentos (FZEA), Universidade de São Paulo (USP), Pirassununga 13635-900, São Paulo, Brazil
2
Instituto de Ciência e Tecnologia, Universidade Federal de Alfenas (UNIFAL), Poços de Caldas 37715-400, Minas Gerais, Brazil
*
Author to whom correspondence should be addressed.
Foods 2025, 14(3), 342; https://doi.org/10.3390/foods14030342
Submission received: 16 December 2024 / Revised: 4 January 2025 / Accepted: 15 January 2025 / Published: 21 January 2025

Abstract

:
Coffee and cocoa agribusinesses generate large volumes of byproducts, including coffee husk, coffee pulp, parchment skin, silver skin, and cocoa bean shell. Despite the rich composition of these materials, studies on biomolecule extraction with green solvents are still scarce, and further research is needed. Extraction methods using alternative solvents to obtain biomolecules must be developed to enhance the byproducts’ value and align with biorefinery concepts. This article reviews the compositions of coffee and cocoa byproducts, their potential applications, and biomolecule extraction methods, focusing on alternative solvents. The extraction methods currently studied include microwave-assisted, ultrasound-assisted, pulsed electric field-assisted, supercritical fluid, and pressurized liquid extraction. At the same time, the alternative solvents encompass the biobased ones, supercritical fluids, supramolecular, ionic liquids, and eutectic solvents. Considering the biomolecule caffeine, using alternative solvents such as pressurized ethanol, supercritical carbon dioxide, ionic liquids, and supramolecular solvents resulted in extraction yields of 2.5 to 3.3, 4.7, 5.1, and 1.1 times higher than conventional solvents. Similarly, natural deep eutectic solvents led to a chlorogenic acid extraction yield 84 times higher than water. The results of this research provide a basis for the development of environmentally friendly and efficient biomolecule extraction methods, improving the utilization of agricultural waste.

1. Introduction

The global production of coffee beans and cocoa beans in the 2023–2024 crop season reached values of approximately 10.15 million and 4.3 million tons, respectively [1,2]. These agricultural commodities, which are widely produced and traded, generate large volumes of waste annually [3], and these byproducts are often discarded incorrectly. Such practices have aroused interest in studies aiming to use these materials for the extraction of bioactive minority compounds (BCs) [4,5], lipids [6], and macronutrients such as proteins [4,7].
Dry and wet processing are the two primary methods to obtain green coffee, the product before roasting. In dry processing, coffee fruits (cherries) are dried to a moisture content of approximately 10%. Subsequently, the dried fruits undergo mechanical dehulling to separate the coffee beans. Coffee husk is generated as a byproduct comprising the outer skin (cherry husk), pulp, parchment, and a portion of the silver skin. This husk fraction, consisting of skin, pulp, mucilage, and parchment, constitutes 40–50% of the dried fruit. In wet processing, coffee fruits are separated by immersion in water. Subsequently, the pulp and outer skin (cherry husk) are mechanically separated. After this step, the coffee seed is covered by the parchment layer, which is, in turn, coated with mucilage, a thin layer rich in pectin. In the subsequent step, the coffee beans undergo fermentation, during which the mucilage is broken down. The coffee beans are washed following fermentation to remove residual pulp material and mucilage. The final two steps before roasting are drying and dehulling, producing green coffee beans [8]. Coffee residues are mostly generated in the bean drying, dehulling, and roasting stages and are currently used for fertilizing coffee plantations and animal feed [9]. The coproducts generated represent approximately 50% of the coffee fruit, equivalent to approximately 5 million tons of waste generated annually [10]. Cherry husk (CH), coffee pulp (CP), parchment skin (PS), and silver skin (SS) are the main processing residues generated up to the bean roasting stage [11]. Research has demonstrated the feasibility of using these residues to produce biobased fuels [8] and extract BCs [12,13].
The main ingredient used to manufacture chocolate and its derivatives is cocoa nibs, obtained by processing cocoa beans. This process can be separated into two stages: preprocessing, carried out by the cocoa producer, and industrial processing. Preprocessing comprises harvesting, pod opening (where the seeds containing the cocoa nibs are separated), fermentation, drying, and storage. In industrial processing, after the cleaning step, the seeds can go directly to roasting or undergo thermal treatment, depending on the industry. In the next step, the seeds are broken, shelled, and winnowed, resulting in the extraction of cocoa nibs [14]. The cocoa bean shell (CBS) is a residue generated in the production of cocoa nibs and is obtained during the peeling of dry or roasted beans. This residue is used as fuel in boilers, as animal feed, and as fertilizer [14,15]. However, this coproduct, which represents 10–17% of the bean weight, is rich in proteins, lipids, and BCs and can be put to better use, contributing positively to the cocoa value chain [14,16].
The use of agroindustry residues as an inexpensive and sustainable source of biocompounds can reduce the negative impacts of the production and processing of coffee and cocoa. Ruesgas-Ramon et al. [17] reported that waste can damage the environment when poorly managed and discarded, causing deterioration of the landscape, the generation of bad odors, and the appearance of fungi that harm crops and human health. Additionally, the reuse of these residues has become attractive because they are rich in several BCs, such as phenolic compounds, tannins, carotenoids, lipids, and proteins, which are important inputs for the production of cosmetics, foods, and drugs [7,14]. The extraction of these compounds can be considered the most critical step for their use, requiring the use of solvents that allow good extraction yield [17].
Efthymiopoulos et al. [18] compared 12 solvents (alkanes and alcohols, along with dichloromethane and toluene) for lipid extraction from coffee grounds. The authors reported that the use of nonpolar solvents such as hexane resulted in a higher extraction yield than the use of alcohols such as ethanol. Hexane is the most widely used solvent for this process because of its high extraction capacity, low cost, high stability, and ease of recovery. However, many studies have focused on the total or partial replacement of hexane because of its high flammability and toxicity. Studies indicate the potential of hexane to cause neoplasms [19,20] and cause losses in some motor functions due to exposure for long periods [21]. These observations led to the introduction of stricter regulations by the European Union, which classified hexane as a neurotoxic substance with suspected reproductive toxicity [22].
Extraction of phenolic BCs is considered challenging because they can be unstable, and their biological activity can be easily affected by process conditions (extraction time and temperature) and the presence of light and oxygenation [23]. The most commonly used method for proteins is extraction with water or saline solution under alkaline conditions, under which most proteins have high solubility. This method has high extraction yields and is inexpensive and easy to perform, but high concentrations of alkaline solutions can cause the Maillard reaction, affecting the main characteristics of the proteins [24]. Therefore, the choice of a suitable solvent for the extraction of BCs and macromolecules is extremely important, i.e., solvents that can be used in reduced proportions relative to the solid matrix, for a short time, and at moderate temperatures without degrading the molecules of interest.
Some classes of alternative solvents, such as supercritical fluids, supramolecular solvents, and natural eutectic solvents, have demonstrated a high capacity for the extraction of BCs, lipids, and proteins in reduced amounts of time, using low amounts of solvents relative to the solid matrix, and at moderate temperatures [25].
Green solvents are intended to replace or eliminate solvents harmful to health and the environment. In addition, they can be obtained from natural and renewable sources, are nontoxic and biodegradable, are easily recoverable, and have high efficiency [26]. The use of green solvents is in line with the Sustainable Development Goals (SDGs) proposed by the United Nations. Concerning SDG 3 (Well-being and Health), the use of green solvents would reduce exposure to toxic chemicals in industrial processes; in the case of SDG 9 (Industry, Innovation, and Infrastructure), the adoption of green solvents would promote the development of innovative and more efficient extraction processes. With regard to SDG 13 (Action Against Global Climate Change), green solvents would replace solvents derived from fossil raw materials [27]. In this context, the specific characteristics of the solvents are linked to the extraction of commercially and industrially valuable biomolecules from agroindustrial residues in an economically and environmentally friendly manner without posing health risks. The solvents to be studied, as substitutes for those conventionally used in extraction processes, must be easily recoverable, selective for the target compound to be extracted, non-fossil-based, nontoxic, and capable of being used in smaller quantities in extraction processes with higher yields and greater efficiency than those using conventional solvents.
In published studies, different technologies have been used for extracting components from coffee and cocoa residues. Ruesgas-Ramon et al. [17] analyzed the extraction of biomolecules, such as phenolic compounds, fibers, and alkaloids, from these residues using natural eutectic solvents based on choline chloride. The authors concluded that the use of this class of solvents allowed high extraction yields with short extraction times and with a low volume of solvent relative to the solid matrix. Soares, Okiyama, and Rodrigues [28] studied the extraction of BCs and lipids from CBS using ethanol and isopropanol as solvents; they reported that it is possible to obtain high yields (30% for ethanol and 70% for isopropanol) from the simultaneous extraction of lipids and BCs. Silva et al. [29] used different extraction methods to obtain BCs from CH using ethanol, water, and an ethanol–water solution (1:1 v/v) as the solvent. The authors reported that the use of hydroalcoholic solution resulted in a high extraction yield of BCs, expressed as the chlorogenic acid equivalent (CGA) (97.89 mg CGA/g of extract).
Based on the above, there is a need to evaluate the use of solvents that have been studied to extract biomolecules from byproducts of coffee and cocoa processing with adequate yields and to respect the principles of green chemistry. The processes of extracting the components of coproducts of coffee and cocoa processing that lead to decreased environmental impact should also be analyzed. Therefore, the present study investigates the application of alternative solvents and technologies for extracting biomolecules from coffee and cocoa residues.

2. Coffee and Cocoa Agroindustry Residues

The generation of waste in agribusiness has increased in recent years due to the high demand for food, driven by population growth, making the search for reuse, recovery, and repurposing of these wastes essential [30]. Therefore, the valorization of agroindustrial byproducts has gained increasing interest because of the high abundance of components such as lipids, proteins, fibers, and BCs [3].
When poorly managed, agroindustry byproducts can generate biotic components that contaminate plantations or degrade the environment, impacting human health and the economy [17,31]. The main cause of pollution from agricultural residues is waste, underutilization, a lack of awareness, and a lack of treatment during disposal. Recently, the conversion of agricultural residues into value-added byproducts has attracted interest because of the growing market demand for products with natural additives and stricter environmental regulations [30].
The circular economy is considered an alternative to the linear production model, aiming to transform disposable goods, such as agroindustry waste, into reusable products, especially as matrices in applications of technological interest and/or high added value [32], resulting in the reduction in discarded waste and the maximization of the resources obtained.
The concept of biorefinery, with the aim of putting agroindustrial waste to better use, is in line with the principles of the circular economy. Biorefinery is based on the principle of “zero waste”, which aims to maximize the use of biological raw materials. Initially, the biorefinery concept was used only for the production of energy (ethanol, hydrogen, and butanol). Over the years, studies have shown that this concept can be extended considerably further, including the production of fertilizers, animal feed, enzymes, and proteins and the extraction of BCs [31].
Beltrán-Ramírez et al. [33] analyzed the commercial value of products derived from agribusiness residues. The authors reported a growing interest by the food and pharmaceutical industries in the extraction of carotenoids, flavonoids, and anthocyanins and in compounds that improve the nutritional and/or technological value of the formulated products, such as adding flavor or attributing properties of interest. The authors also emphasized that the use of agribusiness coproducts could reach USD 46.7 billion in consumer goods, in addition to USD 1.12 billion in functional food products by 2025. These compounds have attracted the interest of researchers and industry, demonstrating that when analyzed within the biorefinery context, agroindustrial plant wastes are a profitable and ecological option for a growing commercial market, with high potential for application in new sectors.

2.1. Coffee

The coffee agroindustry has high global economic importance, and coffee beans are widely traded on stock exchanges as commodities and sold worldwide. Brazil is the world’s largest exporter of coffee, producing approximately 4.2 million tons of beans in 2023–2024 crop years, followed by Vietnam and Colombia. Together, these three countries account for approximately 63.43% of the world’s production [2]. This agroindustry accounted for approximately 309 billion dollars in 2023, and 39.34% of the beans were exported to the European Union, mainly to countries such as Germany, Italy, and France; 20.40% were exported to the United States of America, and 5.60% were exported to Japan [2,9].
Owing to high global coffee consumption, the impacts of the coffee agroindustry have been evidenced in several studies that have focused on the recovery of waste generated by this sector. Bondam et al. [11] reported that approximately 23 million tons of residue are generated annually by the coffee agroindustry in Brazil (the largest producer) through the processes of peeling and mucilage removal to obtain the product of greatest interest, the bean. After harvest, coffee is classified according to weight, size, and shape and can be processed in two ways, dry and wet, with dry coffee being the most commonly used method because it is simpler and better for the environment, generating less solid and liquid waste [9]. Coffee cherries are most often dried in the sun [11] and then cleaned and peeled, which leads to the formation of CH, CP, and PS residues, the latter being the film that covers the coffee bean. SS is obtained from the roasting stage, in which the green bean is subjected to a temperature close to 200 °C to yield the roasted coffee bean [9].
The chemical composition of the residues from the coffee processing stages is variable, depending on the method by which they were obtained (wet or dry), the climate, the soil composition of each location, and the nutrients provided to the plant [34]. Several studies have investigated the composition of residues, and the results are shown in Table 1. Most residues are excellent sources of various biomolecules, such as phenolic compounds, caffeine, proteins, and fibers [8]. Bessada et al. [35] highlighted the differences in the composition of coffee residues and analyzed the countries from which they were obtained, including Brazil, India, Indonesia, Cameroon, and Vietnam. The compositions of the residues, such as the amount of caffeine, differed greatly. For example, samples from India contained 676 mg caffeine/100 g SS, whereas samples from Brazil contained 1210 mg caffeine/100 g SS.
Clark and Macrae [36] highlighted some factors, such as cultivation conditions, like climate and soil, the originating species of the residues (Arabica or Robusta), the degree of coffee roasting, and the methods used for compound extraction and analysis, which play a significant role in shaping the chemical composition of the residues. For instance, the roasting process partially degrades proteins in the dry matter, significantly influencing the final composition.
CH represents 12 to 18% of the weight of coffee cherries on a dry basis [36] and consists of a large number of fibers, such as cellulose and lignin, in addition to proteins. Owing to the high percentage of fibers, this residue can be used in the ceramics industry as a source of replacement for feldspars [34]. Owing to the high number of proteins, CH can act as plasticizers for polymer matrices and facilitate the processing of composites [34]. CH is rich in BCs and can be used in food and pharmaceutical products because of its high composition of tannins and caffeine. Soares et al. [37] studied the solid-state fermentation of CH, adding different concentrations of glucose that resulted in the production of banana and pineapple flavors, as an effort to add a fruity flavor to foods. Furthermore, the authors reported that the CH provided several components necessary for fermentation and biofuel production, such as proteins, carbohydrates, BCs, and minerals. Due to its considerable protein content and nitrogen, CH can be used as a fertilizer and for silage quality improvement [34]. Other applications for CH are presented in Table 2.
Table 1. Characterization of agroindustrial coffee and cocoa byproducts.
Table 1. Characterization of agroindustrial coffee and cocoa byproducts.
ByproductCompositionReferences
Protein
(g/100 g) a
Lipids
(g/100 g) a
Dietary Fiber
(g/100 g) a
Cellulose
(g/100 g) a
Lignin
(g/100 g) a
Total Phenolic
Compounds
(mg GAE/g
Byproduct) b
Caffeine
(mg Caffeine/g
Byproduct)
Moisture (g/100 g)
CH6.6–110.5–326–3216–436–24.54.55–10 1.3–9.85.7–11.98[8,11,34]
CP4–16.2 1–2.912–2410–6314.3–31.50.56–4.5318.6–315–11.6[10,11,38,39,40]
PS0.4–3.10.3–0.989–9240–6025–352.28–2.841.45–587.6–11[10,11,34,41,42]
SS12–202.1–5.854–7410–23.817.8–30.23–17.310–364–7[10,11,34,35,43,44]
CBS9–18.12–2161–65.5814–3532.41–40.24.6–6.91.2–1.444.7–10.1[3,4,14,28,32]
a Composition in dry basis. b GAE = gallic acid equivalent. CH = cherry husk; CP = coffee pulp; PS = parchment skin; SS = silver skin; CBS = cocoa bean shell. Note: the reader is advised to consult the individual references for further information regarding analytical methods, sample preparation, and treatments during analysis.
Table 2. Coffee and cocoa byproducts applications.
Table 2. Coffee and cocoa byproducts applications.
ByproductCurrent/Potential UsesReferences
CHComposting and vermicomposting production;
Production of biofuels, ethanol, and biogas;
Production of mushrooms, energy drinks, and energy bars;
Application in polymers and ceramics;
Food for cows, pigs, and fish;
Production of silage and soil conditioners;
Studies in fermentation processes as a substrate;
Combustion;
Extraction of bioactives: carotenoids, chlorogenic acids, and other polyphenols.
[5,29,34]
CPFermentation as a substrate;
Fertilizer;
Mushroom production;
Animal feed;
Biofuel production;
Pellet manufacturing.
[5,11,34]
PSPyrolysis;
Extraction of bioactive;
Fermentation as a substrate and support for enzyme immobilization;
Production of biofuels and biogas;
Production of panels in civil construction.
[34,42]
SSSource of fiber in functional products;
Color modifier in food;
Functional beverages;
Fertilizers;
Energy source in boilers;
Obtaining ethanol and methanol.
[5,11,34]
CBSFertilizer;
Biogas;
Production of polymeric films;
Production of functional beverages;
Extraction of bioactive;
Formulation of cakes, cookies, chocolates, and beverages;
Fuel in boilers;
Animal feed.
[3,14,15]
CH = cherry husk; CP = coffee pulp; PS = parchment skin; SS = silver skin; CBS = cocoa bean shell.
CP is the residue generated in the largest amount, representing approximately 40% of the weight of the cherry [34]. It is rich in proteins and BCs, such as caffeine, phenolic compounds, chlorogenic acids, and tannins. CP can be used in several industries, such as food, pharmaceutical, and cosmetics [45] (Table 1 and Table 2). Due to its high organic matter content, it can be considered a promising raw material for various microbial processes or as a fertilizer [34]. In addition to the factors mentioned above, such as origin, climate, and soil type in cultivation, the pulping method strongly influences the composition of CP [36]. However, its composition is similar to CH, as both originate from the same part of the coffee cherry [34]. According to Klingel et al. [9], CP can be used to manufacture juices and jellies because of its sweet taste and BC content. In addition, CP can be used in functional antioxidant drinks containing caffeine and polyphenols. Because of the high concentrations of BC and fibers, CP flour can be incorporated into various bakery products, such as breads, cookies, muffins, brownies, spreads, and sauces (Table 2).
PS is a product generated in the coffee cherry peeling stage, representing approximately 6% of the cherry [34]. This residue is rich in fiber (approximately 90% of the composition) and is used in the formulations of new functional foods [8]. PS flour was tested in cookie formulations owing to its high insoluble dietary fiber content, which led to a significant increase in the product’s fiber content [41]. Owing to its reduced composition of proteins and lipids, this residue is used in fermentation processes, in the generation of biofuels, and in pyrolysis processes (Table 2) [44]. Thus, analyzing its chemical composition, PS is a promising source of lignocellulosic materials. Although studies on PS are relatively recent in exploring its use as a food ingredient, coffee parchment’s technological functionalities (water and oil retention capacities, water absorption, swelling, and gelation capabilities), as well as high levels of BC and fiber, open up possibilities as a physiological and technological functional ingredient in food applications and as an active component in food packaging [11,42].
SS is extracted from green coffee beans during the roasting stage, constituting 4.2% of the beans [43]. It is a product that has attracted great industrial interest because of its low moisture content and great potential for BC extraction. SS is rich in proteins, phenolic compounds, and caffeine and is an attractive product for producing functional foods, beverages, and drugs [7] (Table 1). This material has been applied in the formulation of functional yogurts due to their BC levels, with improvements in the bioaccessibility of caffeine and 5-caffeoylquinic acid (5-CQA) [46]. Blinová et al. [43] also highlighted that this coproduct could be used in fermentation as a support and source of nutrients during the production of fructofuranosidase and fructooligosaccharides by the fungus Aspergillus japonicus because of its levels of proteins and phenolic compounds. Furthermore, SS can be used in cosmetics and dermaceuticals due to its powerful antioxidant capacity. SS can be employed in producing biofuels and other industrial fields (Table 2).

2.2. Cocoa

The cocoa bean is the main raw material used in the production of chocolate. However, this is not its only use, as it can also be used in the production of cocoa powder and cocoa butter, with numerous applications in the food and cosmetics industries, among others. The world production of cacao fruit in the 2023–2024 harvest was approximately 4.3 million tons [1], occurring in countries with tropical climates, such as Côte d’Ivoire, Ghana, Indonesia, and Brazil [1,15].
CBS is one of the main residues generated, representing 12 to 20% of the seed [14]. CBS is obtained by dehulling dry cocoa beans; the cotyledon shells are separated to obtain the product of greatest interest, which is used in the form of nibs for the production of chocolate. The husks can also be obtained in the thermal treatment stage, in which the seeds are roasted, followed by separation of the husks and the cotyledon [14].
Approximately 700 thousand tons of CBS are estimated to be generated annually and can be used for nonfood purposes, such as in boilers for energy generation, in the production of fertilizers, and for other purposes [15] (Table 2). However, the application of these residues for purposes where their rich constitution of components of nutritional, pharmaceutical, and/or technological interest are not used can be considered an underutilization of this coproduct. CBS is rich in proteins and BCs, such as caffeine, phenolic compounds, and theobromine (Table 1). They can be used in the formulation of functional foods, such as cereal bars [47], and in bakery products because these residues, when transformed into flour, have a flavor close to the original flavor, increasing nutritional benefits [14,48]. Okiyama et al. [14] reported that CBS has a lower lipid content and a fiber content three times greater than that of nibs.
Studies have shown that the lipids obtained from CBS may be good substitutes for cocoa butter because they have similar fatty acid compositions [28]. The same authors also reported that CBS can be used in the formulation of functional foods owing to the properties of its proteins and because it is rich in various BCs, such as phenolic compounds and caffeine [28,48].

3. Extraction of the Components of Interest from Coffee and Cocoa Residues

To be better used and because they are rich in biocompounds, such as proteins, lipids, fibers, and phenolic compounds, the CH, CP, PS, and SS of coffee, along with CBS, are being evaluated as matrices for the extraction of these biomolecules. To present a more sustainable and profitable way to use these residues, the biorefinery concept can be used [15,17].
Solid–liquid extraction is a technique widely used for the recovery of the aforementioned compounds. It can be applied to different matrices, with a wide variety of solvents, and when combined with agitation and heating, allows acceptable extraction yields to be obtained [11]. The most common disadvantage associated with traditional solid–liquid extraction methods is the need for prolonged periods of contact between solids and solvents, together with the use of temperatures higher than room temperature. These parameters, which are often necessary for some systems, can lead to degradation of the compound to be extracted [23].
The choice of an ideal solvent or method in the biomolecule extraction stage can lead to high yield values, reducing the extraction time and allowing intact extracts to be obtained. The choice of solvent is directly associated with the characteristics of the component to be extracted so that the solvent is able to bind to the solute to be extracted, making the use of each solvent specific for each type or group of molecules [49,50].

3.1. Principles of Biomolecule Extraction Processes

The extraction of proteins, lipids, phenolic compounds, and carotenoids, among other compounds, is highly important for the chemical and food industries. The primary objective of this process is to obtain the compounds of interest with intact integrity and functionality from a matrix of biological origin. Conventional extraction methods, such as maceration, demand large amounts of solvent, energy, and time [51]. Among the parameters that directly influence the yield of biomolecule extraction by conventional methods are temperature, agitation, type of solvent, and pretreatment of the material to be subjected to extraction [51].
Temperature is a critical parameter for biomolecule extraction methods. High temperatures tend to reduce the viscosity of the solvent and extract, increasing the diffusivity of the target component and thus facilitating mass transfer. An increase in temperature also favors the solubility of the solute in the solvent. However, the use of high temperatures can lead to the degradation of BCs and proteins, altering their molecular structure and consequently causing losses in their bioactive properties [23].
Pretreatment of the solid matrix is necessary to improve the extraction yield of a target compound; such pretreatment methods include increasing the surface area to be exposed to the solvent and removing water. Such procedures are performed to make the biomolecules more accessible to the solvent, thus increasing the mass transfer and consequently the extraction yield [52].
Another key factor for the effectiveness of an extraction process is the agitation of the medium, which prevents sedimentation, ensuring uniform contact between the solid matrix and the solvent. Adequate agitation also accelerates diffusivity and ensures greater homogeneity of the solution temperature [51,53].
New techniques have been developed to improve the extraction efficiency of biomolecules, preserving the integrity of BCs, using a smaller volume of preferably nontoxic solvents, and increasing energy efficiency [54]. Alternative extraction methods include microwave-assisted extraction (MAE), ultrasound-assisted extraction (UAE), pulsed electric field-assisted extraction (PEF), pressurized liquid extraction (PLE), and supercritical fluid extraction (SFE).
MAE uses electromagnetic waves, in the frequency range of 0.3–300 GHz, to rotate the dipoles of the molecules and promote ionic conduction, causing heating and disintegration of the cell wall of the solid matrix and facilitating the release of intracellular BCs [23]. Compared with conventional extraction, MAE causes a rapid increase in the local temperature, enabling shorter extraction times and reduced amounts of solvent compared to in solid extraction [55]. According to authors such as Azmir et al. [54] and Osorio-Tobón et al. [23], MAE has a more significant impact on polar BCs, such as phenolic compounds, as these strongly absorb microwave energy, facilitating ionic conduction and dipolar rotation. The electromagnetic waves are composed of two perpendicular oscillating fields, which result in a higher extraction yield following three steps: The first consists of the separation of the BCs from the active sites of the sample caused by the electromagnetic waves. In the second step, solvent diffusion occurs in the sample matrix, which has undergone cellular ruptures caused by the method. Finally, the mass transfer of the BCs to the solvent occurs [54]. The method’s main advantages are the low amount of solvent used, the reduction in thermal gradients, high extraction yields, and a selective technique for extracting organic compounds and BCs [54,55]. However, the most significant disadvantage of MAE is the limited compatibility of materials and solvents, since not all solvents or matrices are suitable for interaction with microwaves. Nonpolar solvents, for example, have a low capacity to absorb microwave energy, which can limit heating efficiency and, consequently, extraction yield [23,56].
UAE consists of the use of ultrasonic waves at frequencies of 20–100 kHz to produce cavitation [23]. This process is highly energetic and consists of a series of compression and decompression cycles in the liquid medium, generating a change in pressure and the formation of bubbles [56]. When these bubbles collapse, they produce very intense shear forces that propagate in the medium, instantly increasing the local temperature to up to 5000 °C at a pressure of 200 MPa, similar to a shock wave. This cavitation phenomenon can cause destruction of the matrix cell walls, allowing the solvent to come into contact with the intracellular components and increasing mass transfer [10,56]. Small volumes of solvent can be used in UAE, but the main disadvantage is that cavitation can cause the degradation of BCs [23]. The equipment used for UAE can vary, with the most basic and accessible being ultrasonic baths. At the same time, there are systems with probes that are more powerful and adaptable, providing a greater concentration of ultrasonic energy. The main components include a power generator, transducer, amplifier, and probe, which convert electrical energy into acoustic waves. Crucial parameters, such as ultrasound power and amplitude, directly influence the extraction yield, increasing solvent penetration and releasing more phenolic compounds [56]. This method allows high extraction and recovery yields of BCs in a shorter process time and can use smaller volumes of solvents, working efficiently with GRAS solvents. In addition, the UAE can be adjusted to meet different types of BCs, whether polar or nonpolar, depending on the extraction conditions (such as solvent, temperature, power, and ultrasound amplitude). However, it is necessary to balance power, temperature, and time to avoid degradation of the target compounds [23,54,55].
Wen et al. [13] investigated the extraction of proteins from dried flakes of coffee silver skin using the MAE and UAE techniques, comparing them with the conventional alkaline extraction technique. The authors reported yields for 10 min of extraction of 43.53% for MAE, 14.04% for UAE, and 6.23% for conventional extraction. They suggested that MAE achieved a higher extraction yield due to microwave irradiation, which causes direct heating within the residue matrix, raising the local temperature and pressure, which improves mass transfer.
Another method used is PEF, which consists of applying a high-voltage electromagnetic pulse (1–80 kV/cm) for a short period to cause damage to the cell wall of the solid matrices, making the cells permeable to the solvent, consequently increasing the extraction yield [32]. This method is especially effective for treating plant matrices with strong cell walls and is also useful for deactivating unwanted microorganisms, functioning as an alternative to pasteurization [32]. In addition, one of the advantages of this method is the possibility of being used for extraction at room temperature, making it a viable alternative for extracting thermolabile BCs [10]. Other advantages of PEF include increased extraction yields, reduced extraction time, and lower solvent consumption than conventional methods. As a disadvantage, the technique can favor the extraction of specific bioactives, such as flavonoids, but with less effect on others, such as tannins. In addition, the effectiveness can vary depending on the variety of raw materials and the industrial treatment applied, requiring specific adjustments for each sample [10,23,32].
Barbosa-Pereira et al. [57] applied PEF as a pretreatment to extract phenolic compounds from CBS and SS, compared with conventional extraction. The polyphenols extraction optimum conditions differed for CBS (11.99 μs PEF pretreatment time, 991.28 number pulses, 1.74 kV cm−1 PEF strength, water–ethanol 61:39 v/v solvent, and 118.54 min of extraction) and SS (5.45 μs PEF pretreatment time, 1000 pulses number, 1.37 kV cm−1 PEF strength, ethanol–water 63:37 v/v, and 75 min of extraction). The authors mentioned that using PEF pretreatment improved phenolic extraction by 75% for CBS and 83% for SS compared to conventional extraction, proving that PEF could damage the cell walls of the residues, leaving the BC accessible to the solvent.
PLE uses solvents at high temperatures (50–200 °C) and pressures (30–200 bar), accelerating extraction compared with conventional methods. High pressures allow an increase in the boiling temperature of the solvents so that they remain in the liquid state while inducing the wall of the solid matrix to break, increasing diffusion and mass transfer [51]. In addition, PLE uses less solvent and can use ecological solvents, such as subcritical water, making the process more sustainable. However, using high pressure and temperature requires expensive equipment and high energy demand, in addition to potentially resulting in lower extraction yields owing to the degradation of thermolabile biomolecules [23,32,58].
SFE uses solvents at temperatures and pressures above the critical point, where there is no longer any distinction between the gaseous and liquid phases. Supercritical fluids are characterized by having gas–liquid properties, such as gas-like diffusivity and viscosity and liquid-like solvation and density [59]. Their properties can be modulated according to the objective of the process in which they are applied, by changing the temperature or pressure, adding cosolvents, and even changing the solvent to be used, the most common being carbon dioxide, chlorodifluoromethane, and nitrous oxide [56,59]. The reduced surface tension and viscosity of the solvent used and a diffusion coefficient close to that of gases increase the penetration of the solvent into solid matrices and facilitate the extraction of the target compounds [56]. SFE, especially using carbon dioxide, does not involve high temperatures, which helps to avoid the thermal degradation of BCs. In addition, extraction efficiency depends on the precise management of temperature and pressure, which may require sophisticated equipment and increase operational costs [10,56,59].
Although the extraction method is linked to the yield and quality of the compounds obtained, the choice of solvent is also a determinant in this process [11]. The use of an appropriate solvent is based on several factors, such as its physical properties, cost, and toxicity. The polarity, affinity for the solute, surface tension, density, and viscosity of the extractant are some of the characteristics that must be analyzed prior to its use in an extraction process [49]. Intermolecular interactions, such as hydrogen bonding and van der Waals forces, facilitate the dissolution of compounds in suitable solvents; more polar solvents are optimal for extracting polar compounds such as phenolic compounds, and nonpolar solvents are optimal for extracting nonpolar compounds such as carotenoids [50,60,61].
Traditional solvents such as methanol and hexane are effective at extracting a wide range of compounds but may present toxicity, separation difficulties, or adverse environmental impacts. An inadequate choice of solvent can limit the efficiency of the process and affect the properties of the extracted biomolecules. Given this scenario, interest in the development and use of green solvents, such as biobased solvents, supercritical fluids, natural eutectic solvents, and supramolecular solvents, is increasing. The use of these solvents can not only reduce the environmental impact but also promote greater selectivity and efficiency of the extraction process.

3.2. Extraction of Biomolecules Using Conventional Solvents

The results of biomolecule extraction depend especially on the type of extraction, the choice of solvent, and the origin of the material and its specific properties [8].
The extraction of phenolic compounds from CH was analyzed by Rebollo-Hernanz et al. [62] using methanol as the solvent; they obtained promising results at 100 °C after 90 min of extraction. Silva et al. [29] obtained better results at shorter times and temperatures when ethanol–water (1:1 v/v) was used as the solvent and demonstrated the greater effectiveness of ethanol than methanol in the extraction of phenolic compounds from CH.
Macías-Garbett et al. [63] used water to extract phenolic compounds from PS and CP in sequential extractions assisted by PEF pretreatment (5 min, pulse frequency of 5 Hz, and pulse voltage of 18 kV) and MAE (540 s, 25–135 °C, 145 mbar). Before extraction trials, PS and CP were sun-dried, and the moisture values were standardized to lower than 10% (weight). The results revealed good extraction yields, with values of 321.17 mg gallic acid equivalent (GAE)/100 g PS and 1443 mg GAE/100 g CP.
Soares et al. [28] evaluated the simultaneous extraction of BCs and lipids from CBS using ethanol and isopropanol as solvents. The authors reported that the use of hydrated alcohols was adequate to extract BCs, mainly alkaloids, and that isopropanol and absolute ethanol provided the best lipid extraction yields.
Botella-Martínez et al. [3] studied the conventional extraction of phenolic compounds from CBS using water. Mellinas et al. [4] used MAE with water as the solvent (5 min, 97 °C, microwave power (500 W), stirring rate (400 rpm), heating rate (20 °C/min), and solid-to-liquid ratio of 0.04 g/mL) and obtained results superior to those obtained by Botella-Martínez et al. [3], demonstrating that MAE is a better extraction method for the production of phenolic compounds.
Aguilera et al. [64] extracted phenolic compounds from PS using a solution of methanol and water (1:1 v/v) as the solvent, whereas Mirón-Mérida et al. [42] used ethanol–water (7:3 v/v). The latter authors obtained 2.14 g of total phenolic compounds (TPCs)/kg PS, values similar to those obtained by Aguilera et al. [64] (2.42 g TPC/kg PS), with a shorter extraction time and temperature, indicating that ethanol was better for the extraction of phenolic compounds from PS.
Wen et al. [65] used UAE for the recovery of phenolic compounds from SS and obtained 8.94 mg GAE/g SS in 10 min using methanol as the solvent. Prandi et al. [7] used the same solvent in a conventional extraction process for 12 h and obtained 5.36 mg GAE/g SS. These studies show the ability of ultrasound to cause greater cell disruption and microcracks, helping increase extraction efficiency in a shorter time interval.
Table 3 shows the use of different methods and solvents for the extraction of different target compounds from the CH, CP, PS, and SS residues of coffee and from CBS. This table presents the results and the process variables studied, indicating the need for the further study of alternative solvents. In these studies, the authors conducted extraction trials using different approaches, either with residues that underwent no further pretreatment or after drying at different levels. Therefore, the readers are advised to consult individual references for additional information regarding raw material preparation.

3.3. Extraction of Biomolecules with Alternative Solvents

The extraction of natural compounds from agroindustry residues is already well established in several production chains, such as vegetable oils, wines, and juices and in the pharmaceutical industry [97]. Traditional solvents, such as hexane and methanol, are the most commonly used solvents in extraction processes [50]. However, most of these solvents have some limitations due to the long extraction times and the need for large amounts of solvent relative to the solid. The use of these solvents can also greatly affect the thermal decomposition of the compound of interest due to the need for high temperatures, in addition to promoting the emission of pollutants into the atmosphere and the release of toxic components during the extraction processes, adding risks to the health of workers and consumers [26].
To mitigate the problems caused by the use of conventional solvents, alternative solvents have been widely studied and have shown good results for the extraction of BCs. An alternative solvent must follow the principles of green chemistry, not release toxic compounds into the environment, present low volatility, be biodegradable, and allow extraction with low energy expenditure [26,50]. Alternative solvents can be divided into four groups: biobased, supercritical, supramolecular, and neoteric.

3.3.1. Biobased Solvents

Biobased solvents are obtained from renewable sources and are generally produced in biorefineries that convert biomass into fuels, energy, and chemicals; they are considered potential substitutes for solvents of fossil origin (petroleum derivatives) [98]. These solvents have low toxicity and can be used in various industrial sectors, such as in foods, pharmaceuticals, paints, cosmetics, and household care products [26,50,98]. Some biobased solvents include alcohols, esters, glycerol derivatives, terpenes, gamma-valerolactone, furan derivatives, and furfurals [50].
In general, biobased solvents have a low viscosity, which facilitates their handling and mass transfer [50]. Biobased solvents have already been used to extract BCs from coffee residues and CBS. Kulkarni et al. [77] analyzed the efficiency of three organic solvents (ethanol, acetone, and ethyl acetate) for the extraction of phenolic compounds from SS. The results showed that ethanol extraction resulted in a greater concentration of phenolic compounds (161 mg GAE/L of extract) than did acetone (22 mg GAE/L of extract) or ethyl acetate (9 mg of GAE/L of extract) extraction. The authors reported that the viscosity and polarity of the solvent directly affected the composition of the extract obtained from SS.
Concerning the suitability of different solvents and techniques for extracting specific biomolecules, the studies compiled in Table 3 indicate that the biobased solvent ethanol, alone or in a mixture with water, is the most employed solvent to extract polar BCs, such as phenolic compounds. Silva et al. [29] analyzed how the ethanol–water solvent hydration level influenced the extraction of BCs from CH. The highest extraction yield values were obtained using a 1:1 (v/v) mixture of ethanol and water for conventional (97.89 mg CGA/g CH) and UAE (90.95 mg CGA/g CH). Aiming to optimize the hydration of ethanol to extract total phenolic compounds and caffeine from PS, Mirón-Mérida et al. [42] perform the Box–Behnken experimental design. The highest extraction yield results were obtained using ethanol–water 7:3 v/v (2.14 g GAE/kg PS and 1.34 g caffeine/kg PS) at 75 °C. The authors highlighted the critical interaction between the temperature of extraction and ethanol hydration, particularly for caffeine extraction.
Buyong and Nillian [79] extracted phenolic compounds from SS using conventional extraction with ethanol, water, and methanol for 30 min at 60 °C. Methanol provided the highest yield of phenolic compounds, 15.24 mg GAE/g of extract, followed by ethanol (11.2 mg GAE/g of extract) and water (9.48 mg GAE/g of extract). The authors suggested the use of ethanol because, in addition to adhering to the principles of green chemistry, the extract provided good yields of the target compounds.
Jensch, Schmidt, and Strube [84] used various pressurized solvents, such as water–ethanol (8:2 to 2:8 v/v), ethanol, methanol, isopropanol, ethyl acetate, and hexane, to extract caffeine and catechin from CBS. The results revealed that water–ethanol solvents exhibited a higher solubilization capability of the BCs than the other extraction solvents evaluated.
Okiyama et al. [86] extracted flavanols and methylxanthines from CBS with pressurized ethanol (10.35 MPa) at temperatures of 60, 75, and 90 °C. The flavanol extraction yield was similar to that obtained by Soares et al. [28] with ethanol in conventional extraction under atmospheric pressure (33 to 38%). However, the use of pressurized ethanol made it possible to obtain theobromine and caffeine extraction yields that were 1.7 to 3.3 times higher than those of conventional extraction [28,86].

3.3.2. Supercritical Fluids

Carbon dioxide (CO2) is the most widely used supercritical fluid due to its moderate critical temperature (31.3 °C) and pressure (7.38 MPa) and recognition as a safe solvent. CO2 is recommended for extracting nonpolar substances; adding cosolvents, such as ethanol, can increase the solubility of polar compounds such as caffeine and phenolic compounds [11,50,58].
CO2 was used to extract caffeine from CH with an extraction yield of 35% [66]. Andrade et al. [70] extracted phenolic compounds from the same material using supercritical CO2 with or without the addition of ethanol as a cosolvent; the results showed that the addition of the cosolvent at any of the concentrations studied did not affect the results, with a maximum value of 28.1 mg GAE/g of extract obtained.
Mazzutti et al. [85] extracted phenolic compounds from CBS via three different methods: SFE using CO2, PLE using ethanol, and Soxhlet extraction with hexane. The best results, 7.2 mg GAE/g of extract, were obtained with pressurized ethanol, followed by Soxhlet extraction (5.62 mg GAE/g of extract) and SFE (4.02 mg GAE/g of extract). Despite having the lowest extraction yield among the methods analyzed, SFE presented a reduced extraction time (2 h) at 50 °C, yielding an extract with higher antioxidant activity and higher carotenoid content than the other methods did.
Nasti et al. [75] studied the extraction of lipids and caffeine from SS by comparing supercritical CO2 SFE and hexane Soxhlet extraction. The authors reported that the lipid yields increased with increasing pressure at constant temperature, as the reduction in CO2 density allowed greater diffusion and mass transfer between the lipids and the solvent. When comparing the extraction methods in terms of yield, SFE and Soxhlet extraction were similar, and it was possible to extract all the lipids contained in the material. The extraction time with supercritical CO2 was considerably shorter (2 h) than the Soxhlet extraction (6 h). With respect to caffeine, SFE resulted in higher yields (0.14 g caffeine/g SS) than those obtained with hexane (0.03 g caffeine/g SS).

3.3.3. Supramolecular Solvents

Supramolecular solvents (SUPRASs) are nanostructured liquids formed by a colloidal suspension of amphiphilic components through a spontaneous process of coacervation and self-assembly [12]. An external agent, such as a change in pH or temperature or the addition of salts, can accelerate the aggregation of amphiphilic compounds [99,100], with the formation of SUPRASs occurring in two steps. In the first stage, a solution of amphiphilic compounds, containing supramolecular aggregates such as micelles or reverse vesicles, is prepared above their aggregation concentration, and the formation of these aggregates depends on the available spaces and the size of the hydrophobic chain of the amphiphile, as well as the chemical groups that come into contact with water [101]. Aggregates occur due to interactions between the hydrophobic and hydrophilic parts of the molecules, leading to the formation of stable structures. The addition of a salt or a change in the pH of the system is subsequently performed to induce coacervation, increasing the size of the supramolecular aggregates by decreasing the repulsion between the components. The growth of these aggregates causes the appearance of droplets that are associated with each other, and because they are less dense than the equilibrium solution (rich in water), they separate from this phase, forming a phase rich in SUPRASs [12].
The SUPRAS phase, which is rich in colloidal aggregates, is of great interest to the academic world and has been studied in many aspects, such as in the formation of polymers [102]; in the extraction of BCs, such as phenolic compounds, proteins, and carotenoids [12,80,101,103]; in the extraction of pesticides [100]; and in water decontamination [99].
Some studies have aimed to extract caffeine from agroindustry residues using different compositions of SUPRASs as solvents. Torres-Valenzuela et al. [80] used octanoic acid and ethanol in the formation of SUPRASs and obtained 3.6 mg of caffeine/g CP at room temperature and after 15 min of extraction. In another study, Torres-Valenzuela et al. [12] compared the efficiency of different SUPRAS compositions in caffeine extraction and obtained the best result, 3.32 mg caffeine/g coffee grounds, using a SUPRAS obtained from a mixture of 24% hexanol, 30% ethanol, and 46% water (v/v). These results were compared with those of the study by Bravo et al. [104], who extracted caffeine from coffee grounds derived from different types of beverage preparations (filter, espresso, plunger, and mocha), and the residues were previously freeze-dried and defatted and subjected to extraction with water at 90 °C. Torres-Valenzuela et al. [12] reported that extraction with SUPRASs provided similar results to extraction with water, without the need for freeze-drying and lipid extraction pretreatments, in addition to being conducted at room temperature.
SUPRASs composed of hexanol, ethanol, and water were used in the extraction of caffeine and chlorogenic acids from coffee grounds, and the results were compared to those obtained via extraction with water, conventionally or in ultrasonic baths [105]. The use of SUPRASs made it possible to obtain results similar to those of extraction with water only for caffeine (0.885 to 0.972 mg caffeine/g dry coffee grounds). In the case of chlorogenic acids, extraction with water at 50 °C provided the best results (1.15 mg CGA/g dry coffee grounds). The authors mentioned that the different behaviors of BCs may be associated with their distribution between the SUPRAS phase (which is rich in amphiphiles) and the equilibrium phase (which is rich in water). These results indicate the need for further study of the thermodynamics related to systems with supramolecular solvents.
In general, studies in the literature indicate that the functional groups of amphiphilic molecules (alcohols or carboxylic acids, for example) influence the ability to establish polar and hydrogen bond interactions with BCs, whereas the size of the carbon chain influences dispersion interactions [12]. On the other hand, amphiphiles with the same chemical function and different carbon chain sizes (octanoic and decanoic acids, for example) have similar BC extraction capacities with different compositions of organic solvents and water [12]. In fact, the shorter the carbon chain of the amphiphile is, the greater its ability to interact via hydrogen bonding, which allows for the use of a smaller amount of organic solvent in the production of SUPRAS. The types of organic solvents (ethanol and tetrahydrofuran, for example) influence the extraction of BC due to their polarities, and the authors recommend the use of ethanol because it is a biobased solvent with low toxicity [12,80].
Research by Torres-Valenzuela et al. [12,80] indicated that the BC extraction yield is a function of the increase in the concentration of amphiphilic compounds in the system, and this behavior results from the increased availability of interactions/bonds with the BCs. With respect to the amount of water in the system, Ballesteros-Gómez and Rubio [106] reported that the size of the cavities formed by hexagonal aggregates increases with the amount of water in the system, which leads to the possibility of using these solvents as liquids with restricted access, i.e., liquids that exclude or minimize the capture of macromolecules (such as proteins) and maximize the capture of micromolecules, such as BCs. It has also been reported that SUPRAS are considered solvents with high efficiency and low toxicity, and the choice of component to be used in SUPRAS synthesis directly influences the toxicity, flammability, and biocompatibility of the solvent [50,106].

3.3.4. Ionic Liquids and Eutectic Solvents

The term neoteric is attributed to unconventional solvents, characterized by the possibility of adjusting their physical and chemical properties according to their composition, which allows them to be used in various applications [50]. The best-known and most-studied solvents in this class are ionic liquids (ILs) and deep eutectic solvents (DESs).
ILs are composed of aqueous solutions of salts composed of cations and anions with a melting point below 100 °C and unique physicochemical properties, such as low vapor pressure, excellent thermal, chemical, and physical stability, and excellent solubility of organic, inorganic, and organometallic compounds [50,69]. However, ILs have low degradability and low biocompatibility with macro- and micromolecules and are, for the most part, very expensive. A remarkable characteristic of ILs in the extraction of BCs is their ability to penetrate and alter the biomass cell walls, facilitating the release of compounds [50,68,69].
Román-Montalvo et al. [68] evaluated the performance of ILs composed of choline and different counterions for the extraction of caffeine from CH. Choline hexanoate presented the best results, with 4221.1 mg caffeine/kg CH, which was higher than that obtained from Soxhlet extraction with ethanol (823.9 mg caffeine/kg CH). The authors attributed the higher extraction yield to the ability of ionic liquids to interact with the alkaloid, ensuring more efficient mass transfer [68].
In 2003, DESs were presented as a new type of neoteric solvent by Abbott et al. [107], who used a mixture of urea and choline chloride, which have high melting points when pure but a much lower melting point than that of the precursors when mixed. Eutectic mixtures have important properties for extraction processes (low volatility, thermal stability, low toxicity, low flammability, and biodegradability) and are widely used owing to the liquefaction and greater solubility provided by the decreased melting point of the mixture. This is due to the formation of hydrogen bonds between the components, which always contain a hydrogen bond donor (HBD) and a hydrogen bond acceptor (HBA) [108]. When these components are derived from two or more natural products, they are called natural deep eutectic solvents (NADESs).
NADESs are considered a subclass of DESs formed, for example, by organic compounds such as amino acids, sugars, and alcohols [109,110]. The most widely used hydrogen acceptor for the formation of NADESs is choline chloride because of its low cost, nontoxicity, biodegradability, and easy synthesis and because it is considered a provitamin in Europe [108]. In addition, Yang [111] reported that the choline cation can interact with cell walls through electrostatic interactions or hydrogen bonds, leading to cell disintegration, which increases BC extraction. However, several other natural compounds can be used. Table 4 presents the main extractants and for what purpose they are considered the best choices in the context of extracting BCs from coffee and cocoa byproducts.
Frade et al. [112] and Hayyan et al. [113] suggested that the toxicity of NADESs is dependent on the composition and concentration of the solution. Compared with aqueous solutions of their pure precursors, NADESs exhibited greater toxicity, which may be related to the structures formed by the eutectic mixtures and the synergistic effects between the components. The most-accepted explanation is that the change in charge that occurs with the hydrogen interactions caused by the components of the NADES increases the toxicity of the mixture [108].
Dai et al. [97] studied several other components for the formulation of NADES, such as lactic acid, malic acid, sucrose, glucose, propane diol, and sorbitol. This study analyzed the effect of adding water in the synthesis of NADES to reduce the viscosity of the medium, since high viscosities reduce mass transfer during extraction. Another variable that was able to reduce the viscosity of the solution was an increase in temperature from 25 to 40 °C. As a result, the authors concluded that the addition of water to a NADES improved the extraction of polar compounds, whereas low amounts of water make NADESs excellent extractants of nonpolar substances.
Owing to their properties, several authors have used NADESs for the extraction of biomolecules from agroindustry residues. Ruesgas-Ramon et al. [17] aimed to extract caffeine and phenolic compounds from CBS with NADESs and analyzed six types of HBDs and HBAs. This study also compared extraction using a NADES with that using a hydroalcoholic solution (ethanol–water 7:3 v/v) and obtained higher extraction yields of phenolic compounds when ethanol was used, followed by a NADES composed of choline chloride and lactic acid. Compared with the results of the study by Jokic et al. [83], who evaluated the extraction of phenolic compounds using subcritical water, the extraction results using NADESs were superior.
da Silva et al. [73] analyzed the extraction of caffeine and chlorogenic acids from different residues of the coffee value chain (mixtures of CH and PS, in addition to CP and SS) under agitation at 60 °C for 30 min. Different compositions of hydrophilic NADES (with the addition of 10 to 20% water) and hydrophobic NADES, in addition to water, were used for comparison purposes. In the case of CP, the NADES composed of guanidinium chloride, lactic acid, and water (GuCl:LA:W, molar ratio 10:17:15) allowed the extraction of 8.88 ± 0.55 mg of caffeine/g CP, a value similar to that obtained by extraction with water (8.47 ± 0.32 mg caffeine/g CP). For SS, the results when choline chloride, lactic acid, and water (CC:LA:W, molar ratio of 1:2:2) and water alone were used were also similar (8.19 ± 0.22 and 8.04 ± 0.13 mg caffeine/g SS, respectively). However, for the extraction of chlorogenic acids, the NADES presented higher values (1.68 mg CGA/g CP) than those obtained with water (0.02 mg CGA/g CP).
A study by Vieira et al. [114] evaluated the effect of the chemical structure of HBDs on the extraction efficiency of phenolic compounds, using choline chloride as an HBA. For the analysis, the following fatty acids were used: linear monocarboxylic acids (acetic acid, propionic acid, butyric acid, and valeric acid), aromatic acids (phenylacetic acid, 3-phenylpropionic acid, 4-phenylbutyric acid, and 5-phenylvaleric acid), dicarboxylic acids (malonic acid and glutaric acid), hydroxy monocarboxylic acids (lactic and glycolic acids), 1-hydroxy dicarboxylic acid (malic acid), and 1-hydroxy tricarboxylic acid (citric acid). Monocarboxylic acids resulted in extraction yields of 23 to 34 mg TPC/g of extract, which are higher than those of the other compounds evaluated, such as citric acid (15 mg TPC/g of extract) and phenylpropanoic acid (14 mg TPC/g of extract). The authors reported that the addition of hydroxyl groups to the HBD structure led to lower extraction yields. An increase in the size of the carbon chain and the presence of a phenyl group were favorable for extraction [114]. In general, the greater the presence of -OH and -COOH groups in the solvent is, the lower the extraction yields of phenolic compounds. Moreover, the presence of water in the solution increased the mass transfer from the matrix to the solvent due to the reduced viscosity, which facilitated the extraction of some BCs, such as caffeine. However, high water addition may cause extraction to not occur properly. The optimal water addition point in the extraction was 50% for the two best DES conditions obtained (choline chloride with butyric acid and choline chloride with phenylpropionic acid). The researchers obtained valuable information that an increase in the solid/liquid ratio (5–120 g/L range) has a slight effect on phenolic compound extraction [114].
Various recovery approaches have been investigated to enhance the sustainability of DES utilization. Techniques like solvent back-extraction and anti-solvent precipitation facilitate the recovery of both DESs and BCs. Nonetheless, research on the reusability of DESs remains relatively scarce, highlighting the necessity for further exploration in this area [50].

4. Conclusions

Coffee and cocoa agroindustry residues have the potential for extracting different components. Coffee pulp and cocoa bean shell presented a relatively high lipid composition, whereas silver skin presented a relatively high protein content. One of the best applications of coffee husk is the extraction of caffeine, while parchment skin best allows for the production of cellulose and lignin.
The evaluation of studies focusing on the extraction of macro- and microcomponents of these residues indicates that the choice of a solvent, or a mixture of solvents at different concentrations, determines the yield of the process and must be made on the basis of the properties of the solute of interest. The extraction of phenolic compounds from these byproducts has mostly been investigated in comparison with the extraction of proteins, lipids, and fibers, indicating the need for intensified research efforts related to the acquisition of these macrocomponents.
The present review contributes to guiding the choice of solvents and the best methods for the extraction of a particular biomolecule from the residues considered. Most extraction processes focus on biobased solvents, especially ethanol, showing that research on the application of SUPRAS and NADES of different compositions is still necessary for the extraction of biomolecules from coffee and cocoa residues.

Author Contributions

Conceptualization, J.P.Z.P. and C.E.d.C.R.; methodology, J.P.Z.P., R.C.B. and C.E.d.C.R.; validation, R.C.B. and C.E.d.C.R.; formal analysis, R.C.B. and C.E.d.C.R.; investigation, J.P.Z.P., R.C.B. and C.E.d.C.R.; resources, C.E.d.C.R.; data curation, R.C.B. and C.E.d.C.R.; writing—original draft preparation, J.P.Z.P.; writing—review and editing, R.C.B. and C.E.d.C.R.; visualization, R.C.B. and C.E.d.C.R.; supervision, R.C.B. and C.E.d.C.R.; project administration, C.E.d.C.R.; funding acquisition, C.E.d.C.R. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by FAPESP (Fundação de Amparo à Pesquisa do Estado de São Paulo—2024/15778-1), CNPQ (Conselho Nacional de Desenvolvimento Científico e Tecnológico—306020/2022-0, C.E.d.C.R. grant), and CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior—Finance Code 001, J.P.Z.P. DS grant).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

No new data were created or analyzed in this study. Data sharing is not applicable to this article.

Conflicts of Interest

The authors declare no conflicts of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.

References

  1. International Cocoa Organization (ICCO). ICCO Quarterly Bulletin of Cocoa Statistics, Volume L, n° 3, Cocoa Year 2023/24. Published on 30 August 2024. Available online: https://www.icco.org/november-2024-quarterly-bulletin-of-cocoa-statistics/ (accessed on 4 December 2024).
  2. United States Department of Agriculture, Foreign Agricultural Service. Coffee: World Markets and Trade. Global Market Analysis, June 2024. Available online: https://www.fas.usda.gov/commodities/coffee (accessed on 4 December 2024).
  3. Botella-Martínez, C.; Lucas-Gonzalez, R.; Ballester-Costa, C.; Pérez-Álvarez, J.Á.; Fernández-López, J.; Delgado-Ospina, J.; Chaves-López, C.; Viuda-Martos, M. Ghanaian Cocoa (Theobroma cacao L.) Bean Shells Coproducts: Effect of Particle Size on Chemical Composition, Bioactive Compound Content and Antioxidant Activity. Agronomy 2021, 11, 401. [Google Scholar] [CrossRef]
  4. Mellinas, A.C.; Jiménez, A.; Garrigós, M.C. Optimization of Microwave-Assisted Extraction of Cocoa Bean Shell Waste and Evaluation of Its Antioxidant, Physicochemical and Functional Properties. LWT 2020, 127, 109361. [Google Scholar] [CrossRef]
  5. Murthy, P.S.; Madhava Naidu, M. Sustainable Management of Coffee Industry By-Products and Value Addition—A Review. Resour. Conserv. Recycl. 2012, 66, 45–58. [Google Scholar] [CrossRef]
  6. Okiyama, D.C.G.; Soares, I.D.; Toda, T.A.; Oliveira, A.L.; Rodrigues, C.E.C. Effect of the Temperature on the Kinetics of Cocoa Bean Shell Fat Extraction Using Pressurized Ethanol and Evaluation of the Lipid Fraction and Defatted Meal. Ind. Crops Prod. 2019, 130, 96–103. [Google Scholar] [CrossRef]
  7. Prandi, B.; Ferri, M.; Monari, S.; Zurlini, C.; Cigognini, I.; Verstringe, S.; Schaller, D.; Walter, M.; Navarini, L.; Tassoni, A.; et al. Extraction and Chemical Characterization of Functional Phenols and Proteins from Coffee (Coffea arabica) by-Products. Biomolecules 2021, 11, 1571. [Google Scholar] [CrossRef]
  8. Gemechu, F.G. Embracing Nutritional Qualities, Biological Activities and Technological Properties of Coffee Byproducts in Functional Food Formulation. Trends Food Sci. Technol. 2020, 104, 235–261. [Google Scholar] [CrossRef]
  9. Klingel, T.; Kremer, J.I.; Gottstein, V.; Rajcic de Rezende, T.; Schwarz, S.; Lachenmeier, D.W. A Review of Coffee By-Products Including Leaf, Flower, Cherry, Husk, Silver Skin, and Spent Grounds as Novel Foods Within the European Union. Foods 2020, 9, 665. [Google Scholar] [CrossRef] [PubMed]
  10. Durán-Aranguren, D.; Robledo, S.; Gomez-Restrepo, E.; Arboleda Valencia, J.; Tarazona, N. Scientometric Overview of Coffee By-Products and Their Applications. Molecules 2021, 26, 7605. [Google Scholar] [CrossRef]
  11. Bondam, A.F.; Diolinda da Silveira, D.; Pozzada dos Santos, J.; Hoffmann, J.F. Phenolic Compounds from Coffee By-Products: Extraction and Application in the Food and Pharmaceutical Industries. Trends Food Sci. Technol. 2022, 123, 172–186. [Google Scholar] [CrossRef]
  12. Torres-Valenzuela, L.S.; Ballesteros-Gómez, A.; Sanin, A.; Rubio, S. Valorization of Spent Coffee Grounds by Supramolecular Solvent Extraction. Sep. Purif. Technol. 2019, 228, 115759. [Google Scholar] [CrossRef]
  13. Wen, L.; Álvarez, C.; Zhang, Z.; Poojary, M.M.; Lund, M.N.; Sun, D.W.; Tiwari, B.K. Optimisation and Characterisation of Protein Extraction from Coffee Silverskin Assisted by Ultrasound or Microwave Techniques. Biomass Convers. Biorefinery 2021, 11, 1575–1585. [Google Scholar] [CrossRef]
  14. Okiyama, D.C.G.; Navarro, S.L.B.; Rodrigues, C.E.C. Cocoa Shell and Its Compounds: Applications in the Food Industry. Trends Food Sci. Technol. 2017, 63, 103–112. [Google Scholar] [CrossRef]
  15. Belwal, T.; Cravotto, C.; Ramola, S.; Thakur, M.; Chemat, F.; Cravotto, G. Bioactive Compounds from Cocoa Husk: Extraction, Analysis and Applications in Food Production Chain. Foods 2022, 11, 798. [Google Scholar] [CrossRef] [PubMed]
  16. Rojo-Poveda, O.; Barbosa-Pereira, L.; Zeppa, G.; Stévigny, C. Cocoa Bean Shell—A By-Product with Nutritional Properties and Biofunctional Potential. Nutrients 2020, 12, 1123. [Google Scholar] [CrossRef] [PubMed]
  17. Ruesgas-Ramón, M.; Suárez-Quiroz, M.L.; González-Ríos, O.; Baréa, B.; Cazals, G.; Figueroa-Espinoza, M.C.; Durand, E. Biomolecules Extraction from Coffee and Cocoa By- and Co-products Using Deep Eutectic Solvents. J. Sci. Food Agric. 2020, 100, 81–91. [Google Scholar] [CrossRef]
  18. Efthymiopoulos, I.; Hellier, P.; Ladommatos, N.; Russo-Profili, A.; Eveleigh, A.; Aliev, A.; Kay, A.; Mills-Lamptey, B. Influence of Solvent Selection and Extraction Temperature on Yield and Composition of Lipids Extracted from Spent Coffee Grounds. Ind. Crops Prod. 2018, 119, 49–56. [Google Scholar] [CrossRef]
  19. Chang, S.S.L.; Kong, Y.L.; Lim, W.X.; Ooi, J.; Ng, D.K.S.; Chemmangattuvalappil, N.G. Design of Alternate Solvent for Recovery of Residual Palm Oil: Simultaneous Optimization of Process Performance with Environmental, Health and Safety Aspects. Clean. Technol. Environ. Policy 2018, 20, 949–968. [Google Scholar] [CrossRef]
  20. Khor, S.Y.; Liam, K.Y.; Loh, W.X.; Tan, C.Y.; Ng, L.Y.; Hassim, M.H.; Ng, D.K.S.; Chemmangattuvalappil, N.G. Computer Aided Molecular Design for Alternative Sustainable Solvent to Extract Oil from Palm Pressed Fibre. Process Saf. Environ. Prot. 2017, 106, 211–223. [Google Scholar] [CrossRef]
  21. Armstrong, C. Longitudinal Neuropsychological Effects of N-Hexane Exposure: Neurotoxic Effects versus Depression. Arch. Clin. Neuropsychol. 1995, 10, 1–19. [Google Scholar] [CrossRef]
  22. Cravotto, C.; Fabiano-Tixier, A.-S.; Claux, O.; Abert-Vian, M.; Tabasso, S.; Cravotto, G.; Chemat, F. Towards Substitution of Hexane as Extraction Solvent of Food Products and Ingredients with No Regrets. Foods 2022, 11, 3412. [Google Scholar] [CrossRef] [PubMed]
  23. Osorio-Tobón, J.F. Recent Advances and Comparisons of Conventional and Alternative Extraction Techniques of Phenolic Compounds. J. Food Sci. Technol. 2020, 57, 4299–4315. [Google Scholar] [CrossRef]
  24. Chen, Q.; Chaihu, L.; Yao, X.; Cao, X.; Bi, W.; Lin, J.; Chen, D.D.Y. Molecular Property-Tailored Soy Protein Extraction Process Using a Deep Eutectic Solvent. ACS Sustain. Chem. Eng. 2021, 9, 10083–10092. [Google Scholar] [CrossRef]
  25. Ballesteros-Gómez, A.; Lunar, L.; Sicilia, M.D.; Rubio, S. Hyphenating Supramolecular Solvents and Liquid Chromatography: Tips for Efficient Extraction and Reliable Determination of Organics. Chromatographia 2019, 82, 111–124. [Google Scholar] [CrossRef]
  26. Chemat, F.; Abert-Vian, M.; Fabiano-Tixier, A.S.; Strube, J.; Uhlenbrock, L.; Gunjevic, V.; Cravotto, G. Green Extraction of Natural Products. Origins, Current Status, and Future Challenges. Trends Anal. Chem. 2019, 118, 248–263. [Google Scholar] [CrossRef]
  27. United Nations Development Programme Sustainable Development Goals. Available online: https://www.undp.org/sustainable-development-goals (accessed on 30 November 2024).
  28. Soares, I.D.; Okiyama, D.C.G.; Rodrigues, C.E. da C. Simultaneous Green Extraction of Fat and Bioactive Compounds of Cocoa Shell and Protein Fraction Functionalities Evaluation. Food Res. Int. 2020, 137, 109622. [Google Scholar] [CrossRef] [PubMed]
  29. Silva, M.d.O.; Honfoga, J.N.B.; de Medeiros, L.L.; Madruga, M.S.; Bezerra, T.K.A. Obtaining Bioactive Compounds from the Coffee Husk (Coffea arabica L.) Using Different Extraction Methods. Molecules 2020, 26, 46. [Google Scholar] [CrossRef] [PubMed]
  30. Amran, M.A.; Palaniveloo, K.; Fauzi, R.; Satar, N.M.; Mohidin, T.B.M.; Mohan, G.; Razak, S.A.; Arunasalam, M.; Nagappan, T.; Sathiya Seelan, J.S. Value-Added Metabolites from Agricultural Waste and Application of Green Extraction Techniques. Sustainability 2021, 13, 11432. [Google Scholar] [CrossRef]
  31. 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. [Google Scholar] [CrossRef]
  32. Mariatti, F.; Gunjević, V.; Boffa, L.; Cravotto, G. Process Intensification Technologies for the Recovery of Valuable Compounds from Cocoa By-Products. Innov. Food Sci. Emerg. Technol. 2021, 68, 102601. [Google Scholar] [CrossRef]
  33. Beltrán-Ramírez, F.; Orona-Tamayo, D.; Cornejo-Corona, I.; Luz Nicacio González-Cervantes, J.; de Jesús Esparza-Claudio, J.; Quintana-Rodríguez, E. Agro-Industrial Waste Revalorization: The Growing Biorefinery. In Biomass for Bioenergy—Recent Trends and Future Challenges. IntechOpen 2019, 11, 13. [Google Scholar]
  34. Hejna, A. Potential Applications of By-Products from the Coffee Industry in Polymer Technology—Current State and Perspectives. Waste Manag. 2021, 121, 296–330. [Google Scholar] [CrossRef] [PubMed]
  35. Bessada, S.M.F.; Alves, R.C.; Costa, A.S.G.; Nunes, M.A.; Oliveira, M.B.P.P. Coffea canephora Silverskin from Different Geographical Origins: A Comparative Study. Sci. Total Environ. 2018, 645, 1021–1028. [Google Scholar] [CrossRef] [PubMed]
  36. Clarke, R.J.; Macrae, R.C. (Eds.) Coffee; Springer: Dordrecht, The Netherlands, 1987; ISBN 978-94-010-8028-6. [Google Scholar]
  37. Soares, M.; Christen, P.; Pandey, A.; Soccol, C.R. Fruity Flavour Production by Ceratocystis Fimbriata Grown on Coffee Husk in Solid-State Fermentation. Process Biochem. 2000, 35, 857–861. [Google Scholar] [CrossRef]
  38. Arango-Agudelo, E.; Rendón-Muñóz, Y.; Cadena-Chamorro, E.; Santa, J.F.; Buitrago-Sierra, R. Evaluation of Colombian Coffee Waste to Produce Antioxidant Extracts. Bioresources 2023, 18, 5703–5723. [Google Scholar] [CrossRef]
  39. Esquivel, P.; Jiménez, V.M. Functional Properties of Coffee and Coffee By-Products. Food Res. Int. 2012, 46, 488–495. [Google Scholar] [CrossRef]
  40. Santos, É.M.d.; Macedo, L.M.d.; Tundisi, L.L.; Ataide, J.A.; Camargo, G.A.; Alves, R.C.; Oliveira, M.B.P.P.; Mazzola, P.G. Coffee By-Products in Topical Formulations: A Review. Trends Food Sci. Technol. 2021, 111, 280–291. [Google Scholar] [CrossRef]
  41. Elba, C.-C.; Bonilla-Leiva, A.R.; Eva, G.-V. Coffee Berry Processing By-Product Valorization: Coffee Parchment as a Potential Fiber Source to Enrich Bakery Goods. J. Food Nutr. Popul. Health 2017, 1, 2–12. [Google Scholar]
  42. Mirón-Mérida, V.A.; Yáñez-Fernández, J.; Montañez-Barragán, B.; Barragán Huerta, B.E. Valorization of Coffee Parchment Waste (Coffea arabica) as a Source of Caffeine and Phenolic Compounds in Antifungal Gellan Gum Films. LWT 2019, 101, 167–174. [Google Scholar] [CrossRef]
  43. Blinová, L.; Sirotiak, M.; Bartošová, A.; Soldán, M. Review: Utilization of Waste From Coffee Production. Res. Pap. Fac. Mater. Sci. Technol. Slovak. Univ. Technol. 2017, 25, 91–101. [Google Scholar] [CrossRef]
  44. Lachenmeier, D.W.; Schwarz, S.; Rieke-Zapp, J.; Cantergiani, E.; Rawel, H.; Martín-Cabrejas, M.A.; Martuscelli, M.; Gottstein, V.; Angeloni, S. Coffee By-Products as Sustainable Novel Foods: Report of the 2nd International Electronic Conference on Foods—“Future Foods and Food Technologies for a Sustainable World”. Foods 2021, 11, 3. [Google Scholar] [CrossRef] [PubMed]
  45. González-González, G.M.; Palomo-Ligas, L.; Nery-Flores, S.D.; Ascacio-Valdés, J.A.; Sáenz-Galindo, A.; Flores-Gallegos, A.C.; Zakaria, Z.A.; Aguilar, C.N.; Rodríguez-Herrera, R. Coffee Pulp as a Source for Polyphenols Extraction Using Ultrasound, Microwave, and Green Solvents. Environ. Qual. Manag. 2022, 32, 451–461. [Google Scholar] [CrossRef]
  46. Bertolino, M.; Barbosa-Pereira, L.; Ghirardello, D.; Botta, C.; Rolle, L.; Guglielmetti, A.; Borotto Dalla Vecchia, S.; Zeppa, G. Coffee Silverskin as Nutraceutical Ingredient in Yogurt: Its Effect on Functional Properties and Its Bioaccessibility. J. Sci. Food Agric. 2019, 99, 4267–4275. [Google Scholar] [CrossRef] [PubMed]
  47. de Barros, H.E.A.; Natarelli, C.V.L.; de Abreu, D.J.M.; de Oliveira, A.L.M.; do Lago, R.C.; Dias, L.L.d.C.; de Carvalho, E.E.N.; Bilal, M.; Ruiz, H.A.; Franco, M.; et al. Application of Chemometric Tools in the Development of Food Bars Based on Cocoa Shell, Soy Flour and Green Banana Flour. Int. J. Food Sci. Technol. 2021, 56, 5296–5304. [Google Scholar] [CrossRef]
  48. Soares, I.D.; Cirilo, M.E.M.; Junqueira, I.G.; Vanin, F.M.; Rodrigues, C.E. da C. Production of Cookies Enriched with Bioactive Compounds through the Partial Replacement of Wheat Flour by Cocoa Bean Shells. Foods 2023, 12, 436. [Google Scholar] [CrossRef]
  49. Lefebvre, T.; Destandau, E.; Lesellier, E. Selective Extraction of Bioactive Compounds from Plants Using Recent Extraction Techniques: A Review. J. Chromatogr. A 2021, 1635, 461770. [Google Scholar] [CrossRef] [PubMed]
  50. Torres-Valenzuela, L.S.; Ballesteros-Gómez, A.; Rubio, S. Green Solvents for the Extraction of High Added-Value Compounds from Agri-Food Waste. Food Eng. Rev. 2020, 12, 83–100. [Google Scholar] [CrossRef]
  51. Patrice Didion, Y.; Gijsbert Tjalsma, T.; Su, Z.; Malankowska, M.; Pinelo, M. What Is next? The Greener Future of Solid Liquid Extraction of Biobased Compounds: Novel Techniques and Solvents Overpower Traditional Ones. Sep. Purif. Technol. 2023, 320, 124147. [Google Scholar] [CrossRef]
  52. Silva, J.M.; Peyronel, F.; Huang, Y.; Boschetti, C.E.; Corradini, M.G. Extraction, Identification, and Quantification of Polyphenols from the Theobroma cacao L. Fruit: Yield vs. Environmental Friendliness. Foods 2024, 13, 2397. [Google Scholar] [CrossRef]
  53. Wypych, G. (Ed.) Handbook of Solvents; ChemTec Pu.: Toronto, ON, Canada, 2014; Volume 2, ISBN 978-1-895198-65-2. [Google Scholar]
  54. Azmir, J.; Zaidul, I.S.M.; Rahman, M.M.; Sharif, K.M.; Mohamed, A.; Sahena, F.; Jahurul, M.H.A.; Ghafoor, K.; Norulaini, N.A.N.; Omar, A.K.M. Techniques for Extraction of Bioactive Compounds from Plant Materials: A Review. J. Food Eng. 2013, 117, 426–436. [Google Scholar] [CrossRef]
  55. Coscarella, M.; Nardi, M.; Alipieva, K.; Bonacci, S.; Popova, M.; Procopio, A.; Scarpelli, R.; Simeonov, S. Alternative Assisted Extraction Methods of Phenolic Compounds Using NaDESs. Antioxidants 2023, 13, 62. [Google Scholar] [CrossRef] [PubMed]
  56. Gil-Martín, E.; Forbes-Hernández, T.; Romero, A.; Cianciosi, D.; Giampieri, F.; Battino, M. Influence of the Extraction Method on the Recovery of Bioactive Phenolic Compounds from Food Industry By-Products. Food Chem. 2022, 378, 131918. [Google Scholar] [CrossRef] [PubMed]
  57. Barbosa-Pereira, L.; Guglielmetti, A.; Zeppa, G. Pulsed Electric Field Assisted Extraction of Bioactive Compounds from Cocoa Bean Shell and Coffee Silverskin. Food Bioprocess Technol. 2018, 11, 818–835. [Google Scholar] [CrossRef]
  58. Mustafa, A.; Turner, C. Pressurized Liquid Extraction as a Green Approach in Food and Herbal Plants Extraction: A Review. Anal. Chim. Acta 2011, 703, 8–18. [Google Scholar] [CrossRef]
  59. Vinitha, U.G.; Sathasivam, R.; Muthuraman, M.S.; Park, S.U. Intensification of Supercritical Fluid in the Extraction of Flavonoids: A Comprehensive Review. Physiol. Mol. Plant Pathol. 2022, 118, 101815. [Google Scholar] [CrossRef]
  60. Goti, D.; Dasgupta, S. A Comprehensive Review of Conventional and Non-Conventional Solvent Extraction Techniques. J. Pharmacogn. Phytochem. 2023, 12, 202–211. [Google Scholar] [CrossRef]
  61. Patra, A.; Abdullah, S.; Pradhan, R.C. Review on the Extraction of Bioactive Compounds and Characterization of Fruit Industry By-Products. Bioresour. Bioprocess 2022, 9, 14. [Google Scholar] [CrossRef] [PubMed]
  62. Rebollo-Hernanz, M.; Cañas, S.; Taladrid, D.; Benítez, V.; Bartolomé, B.; Aguilera, Y.; Martín-Cabrejas, M.A. Revalorization of Coffee Husk: Modeling and Optimizing the Green Sustainable Extraction of Phenolic Compounds. Foods 2021, 10, 653. [Google Scholar] [CrossRef]
  63. Macías-Garbett, R.; Sosa-Hernández, J.E.; Iqbal, H.M.N.; Contreras-Esquivel, J.C.; Chen, W.N.; Melchor-Martínez, E.M.; Parra-Saldívar, R. Combined Pulsed Electric Field and Microwave-Assisted Extraction as a Green Method for the Recovery of Antioxidant Compounds with Electroactive Potential from Coffee Agro-Waste. Plants 2022, 11, 2362. [Google Scholar] [CrossRef] [PubMed]
  64. Aguilera, Y.; Rebollo-Hernanz, M.; Cañas, S.; Taladrid, D.; Martín-Cabrejas, M.A. Response Surface Methodology to Optimise the Heat-Assisted Aqueous Extraction of Phenolic Compounds from Coffee Parchment and Their Comprehensive Analysis. Food Funct. 2019, 10, 4739–4750. [Google Scholar] [CrossRef] [PubMed]
  65. Wen, L.; Zhang, Z.; Rai, D.; Sun, D.; Tiwari, B.K. Ultrasound-assisted Extraction (UAE) of Bioactive Compounds from Coffee Silverskin: Impact on Phenolic Content, Antioxidant Activity, and Morphological Characteristics. J. Food Process Eng. 2019, 42, e13191. [Google Scholar] [CrossRef]
  66. Tello, J.; Viguera, M.; Calvo, L. Extraction of Caffeine from Robusta Coffee (Coffea canephora Var. Robusta) Husks Using Supercritical Carbon Dioxide. J. Supercrit. Fluids 2011, 59, 53–60. [Google Scholar] [CrossRef]
  67. Moreira, M.D.; Melo, M.M.; Coimbra, J.M.; Reis, K.C.d.; Schwan, R.F.; Silva, C.F. Solid Coffee Waste as Alternative to Produce Carotenoids with Antioxidant and Antimicrobial Activities. Waste Manag. 2018, 82, 93–99. [Google Scholar] [CrossRef] [PubMed]
  68. Román-Montalvo, D.; Sánchez, A.; Lorenzana-Licea, E.; Domínguez, Z.; Matus, M.H. Extraction of Caffeine from Coffee Husk Employing Choline-Based Ionic Liquids: Optimization of the Process and Theoretical Study on Solute-Salts Interactions. J. Mol. Liq. 2024, 398, 124286. [Google Scholar] [CrossRef]
  69. Tolesa, L.D.; Gupta, B.S.; Lee, M.-J. Treatment of Coffee Husk with Ammonium-Based Ionic Liquids: Lignin Extraction, Degradation, and Characterization. ACS Omega 2018, 3, 10866–10876. [Google Scholar] [CrossRef] [PubMed]
  70. Andrade, K.S.; Gonalvez, R.T.; Maraschin, M.; Ribeiro-Do-Valle, R.M.; Martínez, J.; Ferreira, S.R.S. Supercritical Fluid Extraction from Spent Coffee Grounds and Coffee Husks: Antioxidant Activity and Effect of Operational Variables on Extract Composition. Talanta 2012, 88, 544–552. [Google Scholar] [CrossRef]
  71. Thaiphanit, S.; Wedprasert, W.; Srabua, A. Conventional and Microwave-Assisted Extraction for Bioactive Compounds from Dried Coffee Cherry Peel by-Products and Antioxidant Activity of the Aqueous Extracts. ScienceAsia 2020, 46S, 12–18. [Google Scholar] [CrossRef]
  72. Barcellos Silva, I.G.C.; Antonio, A.d.S.; de Carvalho, E.M.; dos Santos, G.R.C.; Pereira, H.M.G.; Veiga Junior, V.F. da Method Optimization for the Extraction of Chlorogenic Acids from Coffee Parchment: An Ecofriendly Alternative. Food Chem. 2024, 458, 139842. [Google Scholar] [CrossRef]
  73. da Silva, M.R.; Jelley, R.E.; Carneiro, R.L.; Fedrizzi, B.; Weber, C.C.; Funari, C.S. Green Solvents for the Selective Extraction of Bioactive Compounds from By-Products of the Coffee Production Chain. Innov. Food Sci. Emerg. 2023, 86, 103365. [Google Scholar] [CrossRef]
  74. Zhang, Z.; Poojary, M.M.; Choudhary, A.; Rai, D.K.; Lund, M.N.; Tiwari, B.K. Ultrasound Processing of Coffee Silver Skin, Brewer’s Spent Grain and Potato Peel Wastes for Phenolic Compounds and Amino Acids: A Comparative Study. J. Food Sci. Technol. 2021, 58, 2273–2282. [Google Scholar] [CrossRef] [PubMed]
  75. Nasti, R.; Galeazzi, A.; Marzorati, S.; Zaccheria, F.; Ravasio, N.; Bozzano, G.L.; Manenti, F.; Verotta, L. Valorisation of Coffee Roasting By-Products: Recovery of Silverskin Fat By Supercritical CO2 Extraction. Waste Biomass Valorization 2021, 12, 6021–6033. [Google Scholar] [CrossRef]
  76. Brzezińska, R.; Wirkowska-Wojdyła, M.; Piasecka, I.; Górska, A. Application of Response Surface Methodology to Optimize the Extraction Process of Bioactive Compounds Obtained from Coffee Silverskin. Appl. Sci. 2023, 13, 5388. [Google Scholar] [CrossRef]
  77. Kulkarni, R.M.; Mentha, S.S.; Aishwarya, R.; Mascarenhas, E.W.; Polavarapu, S.; Appaiah, T. Valorization of Waste Coffee Silverskin as a Source of Antioxidant by Extraction with Agitation. Environ. Qual. Manag. 2024, 34, e22209. [Google Scholar] [CrossRef]
  78. Peixoto, J.A.B.; Andrade, N.; Machado, S.; Costa, A.S.G.; Puga, H.; Oliveira, M.B.P.P.; Martel, F.; Alves, R.C. Valorizing Coffee Silverskin Based on Its Phytochemicals and Antidiabetic Potential: From Lab to a Pilot Scale. Foods 2022, 11, 1671. [Google Scholar] [CrossRef] [PubMed]
  79. Buyong, N.L.; Nillian, E. Physiochemical Properties of Sarawak’s Adapted Liberica Coffee Silverskin Utilizing Varying Solvents. Food Sci. Nutr. 2023, 11, 6052–6059. [Google Scholar] [CrossRef]
  80. Torres-Valenzuela, L.S.; Ballesteros-Gómez, A.; Rubio, S. Supramolecular Solvent Extraction of Bioactives from Coffee Cherry Pulp. J. Food Eng. 2020, 278, 109933. [Google Scholar] [CrossRef]
  81. Tran, T.M.K.; Akanbi, T.O.; Kirkman, T.; Nguyen, M.H.; Vuong, Q. Van Recovery of Phenolic Compounds and Antioxidants from Coffee Pulp (Coffea canephora) Waste Using Ultrasound and Microwave-Assisted Extraction. Processes 2022, 10, 1011. [Google Scholar] [CrossRef]
  82. Rojo-Poveda, O.; Zeppa, G.; Ferrocino, I.; Stévigny, C.; Barbosa-Pereira, L. Chemometric Classification of Cocoa Bean Shells Based on Their Polyphenolic Profile Determined by RP-HPLC-PDA Analysis and Spectrophotometric Assays. Antioxidants 2021, 10, 1533. [Google Scholar] [CrossRef] [PubMed]
  83. Jokić, S.; Nastić, N.; Vidović, S.; Flanjak, I.; Aladić, K.; Vladić, J. An Approach to Value Cocoa Bean By-Product Based on Subcritical Water Extraction and Spray Drying Using Different Carriers. Sustainability 2020, 12, 2174. [Google Scholar] [CrossRef]
  84. Jensch, C.; Schmidt, A.; Strube, J. Versatile Green Processing for Recovery of Phenolic Compounds from Natural Product Extracts towards Bioeconomy and Cascade Utilization for Waste Valorization on the Example of Cocoa Bean Shell (CBS). Sustainability 2022, 14, 3126. [Google Scholar] [CrossRef]
  85. Mazzutti, S.; Rodrigues, L.G.G.; Mezzomo, N.; Venturi, V.; Ferreira, S.R.S. Integrated Green-Based Processes Using Supercritical CO2 and Pressurized Ethanol Applied to Recover Antioxidant Compouds from Cocoa (Theobroma cacao) Bean Hulls. J. Supercrit. Fluids 2018, 135, 52–59. [Google Scholar] [CrossRef]
  86. Okiyama, D.C.G.; Soares, I.D.; Cuevas, M.S.; Crevelin, E.J.; Moraes, L.A.B.; Melo, M.P.; Oliveira, A.L.; Rodrigues, C.E.C. Pressurized Liquid Extraction of Flavanols and Alkaloids from Cocoa Bean Shell Using Ethanol as Solvent. Food Res. Int. 2018, 114, 20–29. [Google Scholar] [CrossRef] [PubMed]
  87. Benítez-Correa, E.; Bastías-Montes, J.M.; Acuña-Nelson, S.; Muñoz-Fariña, O. Effect of Choline Chloride-Based Deep Eutectic Solvents on Polyphenols Extraction from Cocoa (Theobroma cacao L.) Bean Shells and Antioxidant Activity of Extracts. Curr. Res. Food Sci. 2023, 7, 100614. [Google Scholar] [CrossRef] [PubMed]
  88. Valencia, A.; Elías-Peñafiel, C.; Encina-Zelada, C.R.; Anticona, M.; Ramos-Escudero, F. Circular Bioeconomy for Cocoa By-Product Industry: Development of Whey Protein-Cocoa Bean Shell Concentrate Particles Obtained by Spray-Drying and Freeze-Drying for Commercial Applications. Food Bioprod. Process. 2024, 146, 38–48. [Google Scholar] [CrossRef]
  89. Ramos-Escudero, F.; Rojas-García, A.; Cádiz-Gurrea, M.d.l.L.; Segura-Carretero, A. High Potential Extracts from Cocoa Byproducts through Sonotrode Optimal Extraction and a Comprehensive Characterization. Ultrason. Sonochem. 2024, 106, 106887. [Google Scholar] [CrossRef] [PubMed]
  90. Švarc-Gajić, J.; Brezo-Borjan, T.; Dzedik, V.; Rodrigues, F.; Morais, S.; Delerue-Matos, C. ESG Approach in the Valorization of Cocoa (Theobroma Cacao) by-Products by Subcritical Water: Application in the Cosmetic Industry. Sustain. Chem. Pharm. 2023, 31, 100908. [Google Scholar] [CrossRef]
  91. Llerena, W.; Samaniego, I.; Vallejo, C.; Arreaga, A.; Zhunio, B.; Coronel, Z.; Quiroz, J.; Angós, I.; Carrillo, W. Profile of Bioactive Components of Cocoa (Theobroma cacao L.) By-Products from Ecuador and Evaluation of Their Antioxidant Activity. Foods 2023, 12, 2583. [Google Scholar] [CrossRef] [PubMed]
  92. Pagliari, S.; Celano, R.; Rastrelli, L.; Sacco, E.; Arlati, F.; Labra, M.; Campone, L. Extraction of Methylxanthines by Pressurized Hot Water Extraction from Cocoa Shell By-Product as Natural Source of Functional Ingredient. LWT 2022, 170, 114115. [Google Scholar] [CrossRef]
  93. Pavlović, N.; Jokić, S.; Jakovljević, M.; Blažić, M.; Molnar, M. Green Extraction Methods for Active Compounds from Food Waste—Cocoa Bean Shell. Foods 2020, 9, 140. [Google Scholar] [CrossRef] [PubMed]
  94. Pavlović, N.; Jakovljević, M.; Molnar, M.; Jokić, S. Ultrasound-Assisted Extraction of Active Compounds from Cocoa Bean Shell. Sci. Prof. J. Nutr. Diet. 2021, 10, 77–88. [Google Scholar]
  95. Disca, V.; Travaglia, F.; Carini, C.; Coïsson, J.D.; Cravotto, G.; Arlorio, M.; Locatelli, M. Improving the Extraction of Polyphenols from Cocoa Bean Shells by Ultrasound and Microwaves: A Comparative Study. Antioxidants 2024, 13, 1097. [Google Scholar] [CrossRef] [PubMed]
  96. Huynh, G.H.; Van Pham, H.; Hong Nguyen, H.V. Effects of Enzymatic and Ultrasonic-Assisted Extraction of Bioactive Compounds from Cocoa Bean Shells. J. Food Meas. Charact. 2023, 17, 4650–4660. [Google Scholar] [CrossRef]
  97. Dai, Y.; Witkamp, G.-J.; Verpoorte, R.; Choi, Y.H. Natural Deep Eutectic Solvents as a New Extraction Media for Phenolic Metabolites in Carthamus tinctorius L. Anal. Chem. 2013, 85, 6272–6278. [Google Scholar] [CrossRef]
  98. Cañadas, R.; Díaz, I.; Rodríguez, M.; González, E.J.; González-Miquel, M. An Integrated Approach for Sustainable Valorization of Winery Wastewater Using Bio-Based Solvents for Recovery of Natural Antioxidants. J. Clean. Prod. 2022, 334, 130181. [Google Scholar] [CrossRef]
  99. Ballesteros-Gómez, A.; Caballero-Casero, N.; García-Fonseca, S.; Lunar, L.; Rubio, S. Multifunctional Vesicular Coacervates as Engineered Supramolecular Solvents for Wastewater Treatment. Chemosphere 2019, 223, 569–576. [Google Scholar] [CrossRef] [PubMed]
  100. Musarurwa, H.; Tavengwa, N.T. Supramolecular Solvent-Based Micro-Extraction of Pesticides in Food and Environmental Samples. Talanta 2021, 223, 121515. [Google Scholar] [CrossRef] [PubMed]
  101. Cai, Z.-H.; Wang, J.-D.; Wang, L.-T.; Zhang, S.; Yan, X.-Y.; Wang, Y.-Q.; Zhao, P.-Q.; Fu, L.-N.; Zhao, C.-J.; Yang, Q.; et al. Green Efficient Octanoic Acid Based Supramolecular Solvents for Extracting Active Ingredients from Zanthoxylum Bungeanum Maxim. Peels. J. Clean. Prod. 2022, 331, 129731. [Google Scholar] [CrossRef]
  102. Yang, X.; Ji, Q.; Liu, J.; Liu, Y. In Situ Supramolecular Polymerization via Organometallic-Catalyzed Macromolecular Metamorphosis. CCS Chem. 2023, 5, 761–771. [Google Scholar] [CrossRef]
  103. Azizi, M.; Tasharofi, S.; Koolivand, A.; Oloumi, A.; Rion, H.; Khaledi, M.G. Improving Identification of Low Abundance and Hydrophobic Proteins Using Fluoroalcohol Mediated Supramolecular Biphasic Systems with Quaternary Ammonium Salts. J. Chromatogr. A 2021, 1655, 462483. [Google Scholar] [CrossRef]
  104. Bravo, J.; Juániz, I.; Monente, C.; Caemmerer, B.; Kroh, L.W.; De Peña, M.P.; Cid, C. Evaluation of Spent Coffee Obtained from the Most Common Coffeemakers as a Source of Hydrophilic Bioactive Compounds. J. Agric. Food Chem. 2012, 60, 12565–12573. [Google Scholar] [CrossRef] [PubMed]
  105. Bouhzam, I.; Cantero, R.; Balcells, M.; Margallo, M.; Aldaco, R.; Bala, A.; Fullana-i-Palmer, P.; Puig, R. Environmental and Yield Comparison of Quick Extraction Methods for Caffeine and Chlorogenic Acid from Spent Coffee Grounds. Foods 2023, 12, 779. [Google Scholar] [CrossRef] [PubMed]
  106. Ballesteros-Gómez, A.; Rubio, S. Environment-Responsive Alkanol-Based Supramolecular Solvents: Characterization and Potential as Restricted Access Property and Mixed-Mode Extractants. Anal. Chem. 2012, 84, 342–349. [Google Scholar] [CrossRef]
  107. Abbott, A.P.; Capper, G.; Davies, D.L.; Rasheed, R.K.; Tambyrajah, V. Novel Solvent Properties of Choline Chloride/Urea Mixtures. Chem. Commun. 2003, 1, 70–71. [Google Scholar] [CrossRef]
  108. Cannavacciuolo, C.; Pagliari, S.; Frigerio, J.; Giustra, C.M.; Labra, M.; Campone, L. Natural Deep Eutectic Solvents (NADESs) Combined with Sustainable Extraction Techniques: A Review of the Green Chemistry Approach in Food Analysis. Foods 2022, 12, 56. [Google Scholar] [CrossRef] [PubMed]
  109. López, R.; D’Amato, R.; Trabalza-Marinucci, M.; Regni, L.; Proietti, 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. [Google Scholar] [CrossRef] [PubMed]
  110. Paiva, A.; Craveiro, R.; Aroso, I.; Martins, M.; Reis, R.L.; Duarte, A.R.C. Natural Deep Eutectic Solvents—Solvents for the 21st Century. ACS Sustain. Chem. Eng. 2014, 2, 1063–1071. [Google Scholar] [CrossRef]
  111. Yang, Z. Toxicity and Biodegradability of Deep Eutectic Solvents. In Deep Eutectic Solvents; Rámon, J.D., Guillena, G., Eds.; Wiley: Hoboken, NJ, USA, 2019; pp. 43–60. [Google Scholar]
  112. Frade, R.F.M.; Simeonov, S.; Rosatella, A.A.; Siopa, F.; Afonso, C.A.M. Toxicological Evaluation of Magnetic Ionic Liquids in Human Cell Lines. Chemosphere 2013, 92, 100–105. [Google Scholar] [CrossRef] [PubMed]
  113. 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. [Google Scholar] [CrossRef]
  114. Vieira, V.; Prieto, M.A.; Barros, L.; Coutinho, J.A.P.; Ferreira, I.C.F.R.; Ferreira, O. Enhanced Extraction of Phenolic Compounds Using Choline Chloride Based Deep Eutectic Solvents from Juglans regia L. Ind. Crops Prod. 2018, 115, 261–271. [Google Scholar] [CrossRef]
Table 3. Methods for the extraction of biomolecules from coffee and cocoa agroindustry byproducts.
Table 3. Methods for the extraction of biomolecules from coffee and cocoa agroindustry byproducts.
ByproductExtraction TargetSolventExtraction ConditionsExtraction MethodResultsReferences
CHTotal phenolic compoundsMethanol90 min
100 °C
Conventional15.99 mg GAE a/g extract[62]
Total phenolic compounds

Flavonoids
Water–ethanol (1:1 v/v)60 min
60 °C

60 min
40 kHz
35 °C
Conventional

Ultrasonic bath-assisted extraction
97.89 mg CGA b/g CH
9.93 mg CE c/g CH

90.95 mg CGA b/g CH
15.69 mg CE c/gCH
[29]
CaffeineSupercritical carbon dioxide (CO2)300 Bar
373 K
SFE84% caffeine extraction yield[66]
CarotenoidsAcetone–methanol (7:3 v/v)30 min
55 °C
Conventional221.35 mg β-carotene/L extract[67]
CaffeineEthanol

ILs (choline hexanoate)
7 h
78 °C

37 min
70 °C
Soxhlet

Conventional
823 mg caffeine/kg CH

4221.1 mg caffeine/kg CH
[68]
LigninILs (diisopropylethylammonium acetate)4 h
120 °C
Conventional71.2% lignin extraction yield[69]
CHLipids

Total phenolic compounds
Supercritical carbon dioxide (CO2)

Ethanol

Ethanol
300 Bar
323.15 K

6 h
78 °C

2 h
55 kHz
25 °C
SFE

Soxhlet

Ultrasonic bath-assisted extraction
1.97 g extract/g CH
28.1 mg CGA/g extract

4.8 g extract/g CH
151 mg CGA/g extract

3.1 g extract/g CH
133.4 mg CGA/g extract
[70]
Caffeine

Total phenolic compounds
Water 100 °C
5 min

900 W
5 min
Conventional

MAE
1.64 µg caffeine/mL extract
130.39 µg GAE/mL extract

1.55 µg caffeine/mL extract
82.25 GAE/mL extract
[71]
PS
Total phenolic compounds

Caffeine
Ethanol–water: (7:3 v/v)50 min
75 °C
Conventional2.14 g GAE/kg PS

1.34 g caffeine/kg PS
[42]
Total phenolic compoundsMethanol–HCl
(4:1 v/v)
90 min
100 °C
Conventional2.3 mg GAE/g PS[64]
PSTotal phenolic compounds

Flavonoids
Water5 min
5 Hz pulse frequency
6 kV/cm
PEF pretreatment and MAE321.17 mg GAE/100 g PS

164.328 mg rutin/100 g PS
[63]
Total phenolic compounds

Caffeine

Chlorogenic acid

Epicatechin
Ethanol4 h
40 KHz
25 °C
Ultrasonic bath-assisted extraction2.515 mg GAE/g extract

24.478 mg de caffeine/100 g extract

7.047 mg CGA/100 g extract

1.155 mg de epicatechin/g extract
[38]
Chlorogenic acidEthanol70 °C
5 min
400 W
2.45 GHz
MAE 7.8 µg CGA/g extract[72]
SSCaffeine

Chlorogenic acid
NADES (choline chloride–lactic acid–water 1:2:2)

Water
30 min
60 °C
Conventional8.19 mg caffeine/g SS
12.56 mg CGA/g SS

8.04 mg caffeine/mg SS
13.82 mg CGA/g SS
[73]
SSTotal phenolic compoundsWater30 min
25 °C
38 W/cm2
UAE2.79 mg GAE/g SS[74]
Total phenolic compounds

Caffeine
Methanol–water
(4:1 v/v)
10 min
60 °C
38 W/cm2
UAE8.94 mg GAE/g SS

4.29 mg caffeine/g SS
[65]
Lipids

Caffeine
Supercritical carbon
dioxide (CO2)–ethanol
(95:5 m/m)
120 min
50 °C
300 Bar
SFE3.3 g lipids/100 g SS

0.14 g caffeine/g SS
[75]
Total phenolic compounds

Caffeine
Water–ethanol (1:1 v/v)60 °C
30 min
Ultrasonic bath-assisted extraction54.37 µmol GAE/g SS
6.75 mg caffeine/g SS
[76]
Total phenolic compoundsWater–ethanol (1:1 v/v)

Acetone

Ethyl acetate
40 °C
90 min
Conventional161 mg GAE/L extract

22 mg GAE/L extract

9 mg GAE/L extract
[77]
CaffeineWater20 kHz
600 W
40 °C
10 min
UAE27.73 mg caffeine/g freeze-dried extract[78]
SSTotal phenolic compoundsEthanol–water (63:37 v/v)1.37 kV·cm−1
100 A
50 Hz
1000 pulses
25 °C

60 rpm
75 min
PEF pretreatment and conventional12.12 mg GAE/g SS[57]
Total phenolic compoundsEthanol–water (95:5 m/m)

Water

Methanol
30 min
60 °C
Conventional11.2 mg GAE/g extract

9.48 mg GAE/g extract

15.24 mg GAE/g extract
[79]
ProteinsSodium hydroxide solution (NaOH) in water
0.6 M
50 °C
200 rpm
10 min

20 kHz
50 °C
10 min
38 W/cm2

434.7 W
10 min
Conventional

UAE

MAE
6.23% recovered protein

14.04% recovered protein

43.53% recovered protein
[13]
CPCaffeineSUPRAS (octanoic acid–ethanol–water)5 min
25 °C
Conventional3.6 mg caffeine/g CP[80]
Total phenolic compoundsWater5 min
5 Hz pulse frequency
6 kV/cm
PEF pretreatment and MAE1433 mg GAE/100 g CP[63]
Total phenolic compoundsEthanol–water (7:3 v/v)20 min
40 kHz
25 °C

5 min
70 °C
800 W
Ultrasonic bath-assisted extraction and MAE328.9 mg GAE/g CP[45]
Total phenolic compounds

Caffeine

Epicatechin
Ethanol4 h
40 KHz
25 °C
Ultrasonic bath-assisted extraction12.628 mg GAE/g extract

85.219 mg caffeine/100 g extract

3.458 mg epicatechin/g extract
[38]
Caffeine NADES (guanidinium chloride–lactic acid–water 10:17:15)

Water
30 min
60 °C
Conventional8.88 mg caffeine/g CP

8.47 mg caffeine/mg CP
[73]
Caffeine

Chlorogenic acid
NADES (choline chloride–lactic acid–water 1:2:1.5)60 min
60 °C
200 W
UAE0.4 g caffeine/100 g CP

0.4 g theobromine/100 g CP
[17]
CPTotal phenolic compounds

Flavonoids

Chlorogenic acid

Caffeine
Water–ethanol
(1:1 v/v)
70 min
700 W
70 °C

35 min
250 W
60 °C
MAE

UAE
47 g GAE/g CP
36 g catechin/g CP
8 mg CGA/g CP
6 mg caffeine/g CP

20.86 g GAE/g CP
18.77 g catechin/g CP
2.64 mg CGA/g CP
3.32 mg caffeine/g CP
[81]
CBSTotal phenolic compoundsWater–ethanol
(1:1 v/v)
120 min
25 °C
Conventional42.97 mg GAE/g CBS[82]
Total phenolic compoundsWater 1 min
25 °C
Conventional8.44 mg GAE/g CBS[3]
Total phenolic compounds

Flavonoids
Water15 min
30 bar
150 °C
PLE37.68 mg GAE/g extract

7.66 g CE/g extract
[83]
Caffeine

Catechin
Water–ethanol
(8:2 to 2:8 v/v)

Ethanol
140 °CPLE2.5 mg de caffeine/g CBS

5 mg CE/g CBS
[84]
CBSTotal phenolic compoundsWater–ethanol (61:39 v/v)1.74 kV·cm−1
100 A
50 Hz
991.28 pulses
25 °C

60 rpm
75 min
PEF pretreatment and conventional33.05 mg GAE/g CBS[57]
Total phenolic compoundsSupercritical carbon dioxide (CO2)

Ethanol

Hexane
2 h
20 MPa
50 °C
11 g/min

20 min
70 °C
10 MPa

6 h
SFE

PLE

Soxhlet
4.0 mg GAE/g extract

7.2 mg GAE/g extract

5.6 mg GAE/g extract
[85]
Total phenolic compounds

Proteins
Water90 min
100 °C

5 min
97 °C
500 W
400 rpm
20 °C/min
Conventional

MAE
22.1 mg GAE/g CBS
87.0 mg BSA/g CBS

35.9 mg GAE/g CBS
580.0 mg BSA/g CBS
[4]
CBSTheobromine

Catechin
Ethanol25 min
60, 75 and 90 °C
10.32 MPa
PLE9.89 mg theobromine
/g CBS

3.5 mg CE/g CBS
[86]
Flavonoids

Total phenolic compounds

Lipids
Ethanol–water (94:6 m/m)180 min
90 °C
Conventional39% total flavanol extraction yield

26.8% total phenolic extraction yield

50% fat extraction yield
[28]
Total phenolic compoundsNADES (choline chloride–lactic acid 1:2) with 50% of water

NADES (choline chloride–glycerol 1:2) with 50% of water

NADES (choline chloride–ethylene glycol 1:2) with 50% of water

Ethanol–water (7:3 v/v)
140 min
30 °C
Conventional14.33 mg GAE/g CBS

11.71 mg GAE/g CBS

11.62 mg GAE/g CBS

9.45 mg GAE/g CBS
[87]
CBSTotal phenolic compoundsEthanol–water (1:1 v/v)2 h
1500 rpm
40 kHz
25 °C
Ultrasonic bath-assisted extraction21.57 mg GAE/g CBS[88]
Total phenolic compounds Ethanol–water (1:1 v/v)15 min
20 kHz
80% amplitude
UAE263.69 mg GAE/g CBS [89]
Proteins

Total phenolic compounds
Water30 min
30 Bar
150 °C
PLE5.71 g protein/100 g dried extract

37 mg GAE/g extract
[90]
Total phenolic compounds

Flavonoids
Methanol–water–formic acid (70:30:0.1%; v/v/v)60 min
25 °C
Ultrasonic bath-assisted extraction42.17 mg GAE/100 mL extract

20.57 mg CE/100 mL extract
[91]
Caffeine

Theobromine
NADES (choline chloride–lactic acid–water 1:2:1.5)60 min
60 °C
200 W
UAE0.1 g caffeine/100 g CBS

0.5 g theobromine/100 g CBS
[17]
Caffeine

Theobromine
Water–ethanol (85:15 v/v)69 Bar
90 °C
PLE 0.45 mg caffeine/100 g CBS

1.95 mg theobromine/100 g CBS
[92]
CBSCaffeine

Theobromine
NADES (choline chloride–oxalic acid 1:1) with 30% of water10 min
60 °C
600–800 W
MAE1.6 mg caffeine/g CBS

5 mg theobromine/g CBS
[93]
Total phenolic compounds

Caffeine
Water44 min
37 kHz
70 °C
70% ultrasound power
Ultrasonic bath-assisted extraction 118.38 mg GAE/g extract

0.741 mg caffeine/g CBS
[94]
Total phenolic compoundsAcidified methanol (trifluoroacetic acid 0.3% v/v)60 min
38 °C

7 h

60 min
38 °C
20.6 kHz
80 W

30 min
90 °C
21.5 kHz
60 W

60 min
50 or 90 °C
21.5 kHz
60 W
Conventional

Soxhlet

UAE

MAE

UAE and MAE
at 50 °C

UAE and MAE
at 90 °C
4.53 mg CE/g CBS

3.54 mg CE/g CBS

15.0 mg CE/g CBS

7.16 mg CE/g CBS

3.53 mg CE/g CBS

4.01 mg CE/g CBS
[95]
CBSTotal phenolic compounds

Theobromine
Water55 min
55 °C
40 kHz

40 min
60 °C
1.5% Viscozyme L
Ultrasonic bath-assisted extraction

Enzyme-assisted extraction
3.89 g GAE/100 g CBS
1.03 g theobromine/100 g CBS

3.90 g GAE/100 g CBS

1.29 g theobromine/100 g CBS
[96]
a GAE = gallic acid equivalent; b CGA = chlorogenic acid equivalent; c CE = catechin equivalent. CH = cherry husk; CP = coffee pulp; PS = parchment skin; SS = silver skin; CBS = cocoa bean shell. Note: the reader is advised to consult individual references for additional information regarding raw material preparation.
Table 4. Main HBDs and HBAs for the formation of NADES used for the extraction of biomolecules.
Table 4. Main HBDs and HBAs for the formation of NADES used for the extraction of biomolecules.
HBDHBAByproductBiomoleculeReference
Lactic acid
Sorbitol
Guanidinium chloride
Choline chloride
CPCaffeine
Chlorogenic acid
[73]
Lactic acidCholine chlorideSSCaffeine
Chlorogenic acid
[73]
Lactic acidCholine chlorideCBSTheobromine
Caffeine
Catechin
Epicatechin
[87]
Lactic acidCholine chlorideCBS
CP
Caffeine
Theobromine
Chlorogenic acid
[17]
Acetamide
Butan 1,4-diole
Fructose
Levulinic acid
Malic acid
Oxalic acid
Choline chlorideCBSGalic acid
Theobromine
Catechin
Caffeine
Epicatechin
[93]
HBD = hydrogen bond donor; HBA = hydrogen bond acceptor; CH = cherry husk; CP = coffee pulp; PS = parchment skin; SS = silver skin; CBS = cocoa bean shell.
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.

Share and Cite

MDPI and ACS Style

Prado, J.P.Z.; Basso, R.C.; Rodrigues, C.E.d.C. Extraction of Biomolecules from Coffee and Cocoa Agroindustry Byproducts Using Alternative Solvents. Foods 2025, 14, 342. https://doi.org/10.3390/foods14030342

AMA Style

Prado JPZ, Basso RC, Rodrigues CEdC. Extraction of Biomolecules from Coffee and Cocoa Agroindustry Byproducts Using Alternative Solvents. Foods. 2025; 14(3):342. https://doi.org/10.3390/foods14030342

Chicago/Turabian Style

Prado, José Pedro Zanetti, Rodrigo Corrêa Basso, and Christianne Elisabete da Costa Rodrigues. 2025. "Extraction of Biomolecules from Coffee and Cocoa Agroindustry Byproducts Using Alternative Solvents" Foods 14, no. 3: 342. https://doi.org/10.3390/foods14030342

APA Style

Prado, J. P. Z., Basso, R. C., & Rodrigues, C. E. d. C. (2025). Extraction of Biomolecules from Coffee and Cocoa Agroindustry Byproducts Using Alternative Solvents. Foods, 14(3), 342. https://doi.org/10.3390/foods14030342

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop