Article

Biomolecules extraction from coffee and cocoa by‐ and co‐products using Deep Eutectic Solvents

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Abstract

Background: Coffee pulp (CP), cocoa husk (CH), and pod husk (CPH) are the main agro-residues from coffee and cocoa industries. They are sources of useful biomolecules, such as phenolic compounds, fibers, and alkaloids, among others. In this study, different compositions of deep eutectic solvents (DES) were investigated as a green and sustainable extraction media, with respect to their extraction capacity. The extraction yields were evaluated using heat stirring assisted extraction (HSE) or ultrasound-probe assisted extraction (UPAE). Results: The results showed an important effect of the DES composition. Choline chloride (ChCl) based-DES were the most effective, specifically lactic acid:ChCl (2:1 mole ratio), and the extraction capacity of DES was higher with UPAE (3 min/constant duty cycle (200 W)), in comparison with HSE (1h / 30 min). Chlorogenic acid, caffeine, and theobromine were identified as the main bioactive compounds. Interestingly, under specific conditions, DES allowed the formation of a molecule, identified as furfural by UPLC-MS, which could not be obtained using conventional extraction solvent (EtOH 70 % v/v). Conclusion: DES showed a sustainability and high extraction capacity of biomolecules. In addition, their use as extraction solvents could lead to the formation and production of valuable building block molecules from plant biomass. This article is protected by copyright. All rights reserved.

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... Mycorrhizal associations can overcome nutrient limitations to plant growth by increasing the availability of phosphorus. Fungi can release phosphorus into the soil solution from organic phosphates with the help of phosphatases, thereby providing access for plants to otherwise insoluble forms of phosphorus [105]. The greater availability of phosphorus to the mycorrhizal plant host is dependent on the ability of its symbiont to absorb and translocate inorganic phosphates to the host roots and to access the forms of phosphorus 'locked up' in organic debris [106,107]. ...
... There are three types of pistillate line, i.e., N, S, and NES, which could be used for hybrid production. In the N type, the occurrence of only female flowers is controlled by a recessive gene (ff); in the S type, the production of only female flower is controlled by a polygenic complex with dominant and epistatic effects; and in the NES type, the induction of female is also controlled by a recessive gene (ff), but sexual reversion occurs when the air temperature is more than 31°C [105][106][107]. The seed yield and seed oil content are usually inherited by quantitative manner. ...
... Major flavonoids were identified as quercetin, kaempferol, and myricetin. Very recently, Ruesgas-Ramón et al. [105] used agro-residues from coffee and cocoa industries to recover biomolecules using DESs. The authors reported that the use of lactic acid-ChCl (2:1) provided higher phenolics extraction with ultrasound-probe-assisted extraction than heat stirring-assisted extraction. ...
Book
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It is currently well known and widely accepted that farmers are the general managers of the Earth’s land surface worldwide. Furthermore, they will continue to shape agricultural environments in the coming decades. The generation of increased and improved innovative methodologies and approaches that guarantee the sustainability of crop production, simultaneously with ecosystem services, is a challenging scientific area, largely led by ecologists, agronomists, and theoreticians, who must address this task as a joint effort. Agricultural ecosystems offer a variety of benefits to the global population, and these are recognized as Ecosystem Services. In this context, it has been acknowledged that ecosystem services are both actively or passively engaged in enhancing the well-being of the global population. Accordingly, as defined in the Millennium Ecosystem Assessment (2005), the main role of agricultural practices is to support provisioning ecosystem services, mainly through the manufacture of supplies and educational management. The ecological tools underlying ecosystem services take into account the complexity of the many possible relationships between species of economic importance and the characteristics of local ecosystems. Furthermore, the consequences of biodiversity on the mechanisms underlying most ecosystem services are nowadays well recognized and known in most cases, both empirically and theoretically. In an ideal condition, most, if not all, ecosystem services should also be considered when resource management decisions are taken and should be included at different scales, both spatial and temporal. It is also important to avoid overlooking the interactions between biodiversity and stakeholders, in order to maximize the benefits derived from such practices and minimize the cost through appropriate decisions. However, relationships between agricultural practices and ecosystem services are, in most cases, not totally understood. The ecological mechanisms underlying ecosystem services include multifaceted interactions not only between organisms, but also among different types of organisms, and cultural practices and stakeholder strategies can either inhibit or enhance the ecosystem services. In reality, mechanistic modeling tools examining the consequences of management options on the provisions of most of the various ecosystem services are still lacking. There is a need for innovative cropping systems to be designed at field and landscape scales, and an even larger scales, to aid future planning, organization, and strategies, in which the complexity of the interactions encompassed by ecological and decisional networks must be included. Today, it is accepted worldwide that an AGROECOSYSTEM represents a very complex environmental system in which many species interact, driving a variety of ecological processes at different spatial scales. In addition, agroecosystems are characterized by strong and interrelated interactions among ecological and soil management processes. These interactions encompass, in a general conceptual framework, the relationships between ecological and food webs, hosts and pathogens, and those involving spatial interdependence between localities. Under this scenario, an “interaction networks” model enables researchers in the field to (1) analyze and understand the emergent properties of complex systems, and (2) develop universal rules that allow individual stakeholders to make decisions regarding the outcomes of the ecosystem. IV This book, “Agroecosystems – Very Complex Environmental Systems,” aims to present an update on different aspects associated with the importance of sustainable agriculture. It was our intention to gather information from diverse sources in this volume and to give some real-life examples, extending the appreciation of the complexity of this subject in a way that may stimulate new approaches in relevant fields. This book includes seven general chapters highlighting different aspects of agroecosystems worldwide. The first chapter describes the fungal endophytes of Australian orchid species; these endophytes exploit large areas of the soil, to which orchid roots have no access, and acquire both organic and inorganic nutrients beyond the depletion zone at low carbon cost. Several integrated approaches have been developed for the conservation, management, and restoration of these terrestrial orchids in the wild because appropriate conservation priorities need to be established urgently to prevent the loss of habitats for these endangered species. This chapter also focuses on the protection of these endangered Australian orchid species by developing an understanding of the nutritional behaviour of their endophytes. The second chapter aims to describe the impact of the plant hormone brassinolide on two varieties of fig from Indonesia and Malaysia, stressing the significant effect of interactions between brassinolide and diversity on fig growth and physiological changes, except in respect of plant height and dry biomass. The third chapter documents the relationship between resistant varieties of hybrid strawberries Fragaria × ananassa Duch. and negative environmental conditions. These conditions include physiological and biochemical indicators of resistance during autumn hardening and after temperature stress in winter that resulted in changes in the antioxidant system, interruptions of the protein-carbohydrate complex, accumulation of membrane lipoperoxidation products, and changes in the fractional composition of water in the leaves. The fourth chapter has been written to provide botanical descriptions of the castor bean or castor oil plant, belonging to the monotypic genus Ricinus, describing its ecology, agro-technology, and many industrial uses. At present the plant is in increasing demand in the international market for its more than 700 uses, ranging from medicine and cosmetics to biodiesel, plastics, and lubricants. The fifth chapter is focused on the development of a defined, highlyreliable, and integrated methodology for identifying the causes of contamination of agroecosystems in southern Italy, namely asbestos and illegal burial of waste, in the soil as well as microplastic pollution. This chapter also discusses innovative and high-speed approaches to obtaining ever more precise data on environmental degradation. The sixth chapter is an update on the literature regarding the use of deep eutectic solvents to treat lignocellulosic wastes within the field of biomass valorization. Therefore, this chapter emphasizes how the preparation of novel deep eutectic solvents and improving treatment conditions will help to solve the environmental problems originating from agro-industrial wastes and also to develop new platforms for the production of valuable products such as chemicals, biofuels, and bioactive phenolic compounds. Finally, this book includes a chapter that discusses the effects of the application of blue-green algae, which enhances the morphological and photosynthetic efficiency of the rice plant under greenhouse conditions, stressing that the application of such a bio-mixture in agriculture not only increases crop yield but also maintains our environment sustainably. Finally, as indicated in a book we published some years ago, entitled “Organic Fertilizers – From Basic Concepts to Applied Outcomes”, it seems obvious “that future agricultural practices will irreversibly shape the Earth’s land surface, including its species, geochemistry, and disponibility of surface to the people living on it”. We hope that the information presented in this book will be of value to those directly XIV V engaged in the management and use of agroecosystems, and that this book will continue to meet the expectations and needs of all those interested in the different ways that agroecosystems can be directed to achieve sustainable agriculture without compromising environmental integrity. The chapters provided by the authors in this field of research are gratefully acknowledged. The publication of this book is orientated to those researchers, scientists, engineers, teachers, graduate students, agricultural agronomists, farmers, and crop producers who can use these different results to develop an understanding of the complexity of an agroecosystem and the different aspects and relationships among the different entities involved. The concepts of agroecosystems and ecosystem services can help scientists determine how much of each service is provided throughout the many scales of the networks (field, farm, and/or landscape) at the different ecological levels (individuals, species, communities, and ecosystems), allowing innovative strategies to be developed in ecosystem services management and the damage caused by agroecosystems to be minimized.
... The use of NADES has been selected as the most convenient green method for coffee extraction, which is combined with other extraction methods i.e., ultrasonic, microwave, supercritical fluid to extract phenolics and caffeine . [45,46] Green extraction methods must maximize profits, while being safe, cheap, and robust. For decaffeination of coffee and for full utilization of polyphenols in nutraceuticals, an appropriate extraction method is required for caffeine and polyphenols as well as other secondary metabolites. ...
... [162] On the other hand, choline chloride-lactic acid at the molar ratio 1:2 showed highest extractability of CGA and caffeine from coffee pulp. [46] Asides, formation of a new compound also tentatively identified as furfural was noted upon extraction with this solvent, which could be due to the reaction between carbohydrates in the coffee pulp and acid in NADES. [43,161] NADES with organic acids and sugars were also studied for the extraction of coffee compounds. ...
... Nonconventional methods, such as SWE, UAE, MAE and NADES produced higher CGA and caffeine content in coffee extracts compared to conventional methods. [45,46] This is related to improved extraction effectiveness due to cell wall breakage and the release of CGA, and caffeine from the cells by non-conventional methods, and in accordance with previous results recorded on eggplants for CGA extraction from a different matrix . [165] The combination of extraction methods showed significantly (p < 0.05) higher CGA and caffeine levels compared to traditional methods, with an additional advantage of shorter extraction time. ...
Article
Coffee is recognized worldwide as a top beverage owing to its several associated health benefits mediated by a complex mixture of unique bioactive substances. Chlorogenic acids are the key components of the phenolic fraction in green coffee seeds, accounting for up to 14% of the dry matter. The manufacturing of decaffeinated coffee demands efficient caffeine extraction from seeds and spent without solvent history effect for safety considerations. This has prompted researchers to investigate eco-friendly and cost-effective extraction technologies. Current extraction processes are not environmentally sustainable and have harmful consequences on humans. To date, developing a single standard method for effective extraction of certain complex compounds from coffee seeds remained a challenging procedure. The current review aims to give updated technical information regarding coffee plant green extraction methods, their advantages and disadvantages, and factors affecting efficacies for the recovery of bioactive compounds in coffee seeds and coffee spent. A comparative review of the uses of innovative green extraction techniques for coffee bioactive substances is introduced to present alternatives to conventional extraction methods. The most interesting finding was that the maximum total extractions of catechin (50.6 g/100 g) and caffeine (46.2 g/100 g) were achieved with enzymes in pressurized liquid extraction (PLE), and PLE-assisted with enzymes exhibited an enhancement in total phenolics and overall antioxidant compared to 50% hydro-ethanolic solutions. In addition, it has been claimed that the ultrasonic extraction can cut extraction time by 37% and temperature by 13%. These green extraction techniques represent favorable approaches to the exploitation of coffee chemicals as bioactives to explore their wide-reaching applications at an industrial level and for their valorization
... A biorefinery approach was engaged by Ruesgas-Ramón et al., to isolate phenolic acids from coffee and cocoa by-products. [39] Coffee and cocoa consumption generates solid wastes, such as pulp and husk, which represents million tons of waste. Coffee pulp represents around 40% of the fresh weight of coffee fruits, whereas cocoa husk and cocoa pod husk are the main co-products from the cocoa manufacturing. ...
... The study carried out by Ruesgas-Ramón et al. [39] focused on the investigation of six NaDES based on Choline Chloride or Betaine as HBA for polyphenol extraction. Two different extraction conditions were compared: ultrasound-probe assisted extraction and heat stirring-assisted extraction. ...
Article
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With the growing interest in more environmentally friendly solvents and processes, the introduction of Natural Deep Eutectic Solvents (NaDES) as low cost, non-toxic and biodegradable solvents represent a new opportunity for green and sustainable chemistry. Thanks to their remarkable advantages, NaDES are now arousing growing interest in many fields of research such as food, health, cosmetics and biofuels. Around the world, NaDES are seen as a promising alternative to commonly used petrochemical solvents. The objective of this review is to draw up a panorama of the existing skills on NaDES in French laboratories and industries for the valuation of natural products. This review therefore focuses on current applications, skills and perspectives, in order to analyze the place of French research in the use of NaDES for the valorization of biomass since 2015.
... It was found that the water content in different choline chloride-based DES influences the oxidation, while the extraction time and temperature showed no significant impact. Heat-stirring assisted extraction (HSE) or ultrasound probe-assisted extraction was used along with deep eutectic solvents for preparing extracts rich in phenolics and alkaloids [14]. It was found that ultrasound (3 min, 200 W) DES (lactic acid:ChCl) was superior in extracting the compounds (chlorogenic acid, caffeine, and theobromine) compared to HSE. ...
... These bioactive compounds showed remarkable biological activities, which could provide functionality to food products ( Figure 2). R PEER REVIEW 9 of 15 extraction was used along with deep eutectic solvents for preparing extracts rich in phenolics and alkaloids [14]. It was found that ultrasound (3 min, 200 W) DES (lactic acid:ChCl) was superior in extracting the compounds (chlorogenic acid, caffeine, and theobromine) compared to HSE. ...
Article
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Cocoa husk is considered a waste product after cocoa processing and creates environmental issues. These waste products are rich in polyphenols, methylxanthine, dietary fibers, and phytosterols, which can be extracted and utilized in various food and health products. Cocoa beans represent only 32–34% of fruit weight. Various extraction methods were implemented for the preparation of extracts and/or the recovery of bioactive compounds. Besides conventional extraction methods, various studies have been conducted using advanced extraction methods, including microwave-assisted extraction (MAE), ultrasonic-assisted extraction (UAE), subcritical water extraction (SWE), supercritical fluid extraction (SFE), and pressurized liquid extraction (PLE). To include cocoa husk waste products or extracts in different food products, various functional foods such as bakery products, jam, chocolate, beverage, and sausage were prepared. This review mainly focused on the composition and functional characteristics of cocoa husk waste products and their utilization in different food products. Moreover, recommendations were made for the complete utilization of these waste products and their involvement in the circular economy.
... In the case of extraction of phenolic acids by the UAE-DES/NADES methods, most authors have found choline chloride:lactic acid-based DES (molar ratio usually 1:2) as the most promising solvent [103][104][105]. The combination of choline chloride with other organic acids such as: p-toluenesulfonic acid [66], oxalic acid [106] and citric acid [107] is also interesting. ...
... Choline chloride:organic acid-based DES/NADES in combination with UAE is the most effective extraction methodology described for the isolation of phenolic acids from the various plant matrices [66,[105][106][107]126]. ...
Article
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The growing interest of the food, pharmaceutical and cosmetics industries in naturally occurring bioactive compounds or secondary plant metabolites also leads to a growing demand for the development of new and more effective analysis and isolation techniques. The extraction of bioactive compounds from plant material has always been a challenge, accompanied by increasingly strict control requirements for the final products and a growing interest in environmental protection. However, great efforts have been made in this direction and today a considerable number of innovative extraction techniques have been developed using green, environmentally friendly solvents. These solvents include the deep eutectic solvents (DES) and their natural equivalents, the natural deep eutectic solvents (NADES). Due to their adjustable physical-chemical properties and their green character, it is expected that DES/NADES could be the most widely used solvents in the future, not only in extraction processes but also in other research areas such as catalysis, electrochemistry or organic synthesis. Consequently, this review provided an up-to-date systematic overview of the use of DES/NADES in combination with innovative extraction techniques for the isolation of bioactive compounds from various plant materials. The topicality of the field was confirmed by a detailed search on the platform WoS (Web of Science), which resulted in more than 100 original research papers on DES/NADES for bioactive compounds in the last three years. Besides the isolation of bioactive compounds from plants, different analytical methods are presented and discussed.
... Silva et al. [15] extracted phenolic compounds with ethanol and water: ethanol mixtures. Ruesgas-Ramon at al. [46] used deep eutectic solvents, whereas Andrade et al. [47] employed supercritical fluids to extract phenolic compounds from the coffee husk. The aqueous extract presented concentrations similar to those obtained with eutectic solvents but much lower than those obtained with ethanol and supercritical carbon dioxide. ...
... A comprehensive analysis was carried out to find 18 compounds, including hydroxybenzoic, hydroxycinnamic, phenylacetic acids, monomeric and dimeric flavan-3ols, and flavonols. Previous studies have been focused on the main phenolic compounds (chlorogenic, protocatechuic, gallic, and caffeic acids) and the caffeine content [15,46,47]. ...
Article
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This study aimed to model and optimize a green sustainable extraction method of phenolic compounds from the coffee husk. Response surface methodology (RSM) and artificial neural networks (ANNs) were used to model the impact of extraction variables (temperature, time, acidity, and solid-to-liquid ratio) on the recovery of phenolic compounds. All responses were fitted to the RSM and ANN model, which revealed high estimation capabilities. The main factors affecting phenolic extraction were temperature, followed by solid-to-liquid ratio, and acidity. The optimal extraction conditions were 100 °C, 90 min, 0% citric acid, and 0.02 g coffee husk mL−1. Under these conditions, experimental values for total phenolic compounds, flavonoids, flavanols, proanthocyanidins, phenolic acids, o-diphenols, and in vitro antioxidant capacity matched with predicted ones, therefore, validating the model. The presence of chlorogenic, protocatechuic, caffeic, and gallic acids and kaemferol-3-O-galactoside was confirmed by UPLC-ESI-MS/MS. The phenolic aqueous extracts from the coffee husk could be used as sustainable food ingredients and nutraceutical products.
... Previous studies have also investigated the extraction of compounds from coffee by-products using ultrasound-assisted and supercritical extractions and organic or deep eutectic solvents. Similarly, the major phenolic compounds found were chlorogenic, protocatechuic, gallic, and caffeic acids, and the caffeine content was remarkable (35)(36)(37). Thus, the primary bioactive compounds present in CSE and CHE were considered as treatments used in the form of standard solutions for the following analyses (kaempferol was tested as aglycone, being the latter the bioavailable form). ...
Article
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Coffee by-products contain bioactive compounds that have been shown to have the capacity to modulate human metabolism. The goal of this study was to investigate the effects of the main bioactive compounds in coffee by-products and two aqueous extracts from the coffee husk and silverskin on the activation of fibroblast growth factor 21 (FGF21) signaling and the subsequent regulation of mitochondrial bioenergetics and lipid and glucose metabolism. HepG2 cells treated with palmitic acid (PA) were used in a non-alcoholic fatty liver disease (NAFLD) cell model. The bioactive compounds from coffee by-products (50 µmol L −1) and the aqueous extracts from the coffee silverskin and coffee husk (100 µg mL −1) increased ERK1/2 phosphorylation and the secretion of FGF21 (1.3 to 1.9-fold). Coffee by-products' bioactive compounds counteracted inflammation and PA-triggered lipotoxicity. Oxidative stress markers (ROS, mitochondrial superoxide, and NADPH oxidase) and the activity of antioxidant enzymes (superoxide dismutase and catalase) were modulated through the activation of Nrf2 signaling. Mitochondrial bioenergetics were regulated by enhancing respiration and ATP production via PGC-1α, and the expression of oxidative phosphorylation complexes increased. Coffee by-products' bioactive compounds decreased lipid accumulation (23-41%) and fatty acid synthase activity (32-65%) and triggered carnitine palmitoyltransferase-1 activity (1.3 to 1.7-fold) by activating AMPK and SREBP-1c pathways. The GLUT2 expression and glucose uptake were increased (58-111%), followed by a promoted glucokinase activity (55-122%), while glucose production and phosphoenolpyruvate carboxykinase activity were reduced due to IRS-1/Akt1 regulation. The bioactive compounds from coffee by-products, primarily chlorogenic and protocatechuic acids, could regulate hepatic mitochondrial function and lipid and glucose metabolism by activating FGF21 and related signaling cascades.
... NaDES are stable eutectic mixtures composed of a hydrogen bond acceptor (HBA) and a hydrogen bond donor (HBD). Recently, Ruesgas-Ramón et al. [62] tested six different DES using heat-stirring assisted extraction (1 h, 60 °C) to extract CGAs from coffee and cocoa by-products. The extraction yield was compared with the results obtained in the same experimental conditions using 70% ethanol. ...
Article
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The agri-food sector produces a huge amount of agri-food wastes and by-products, with a consequent great impact on environmental, economic, social, and health aspects. The reuse and recycling of by-products represents a very important issue: for this reason, the development of innovative recovery and extraction methodologies must be mandatory. In this context of a circular economy, the study of green extraction techniques also becomes a priority in substitution of traditional extraction approaches. This review is focused on the recovery of chlorogenic acids from agri-food wastes, as these compounds have an important impact on human health, exhibiting several different and important healthy properties. Novel extraction methodologies, namely microwave and ultrasound-assisted extractions, supercritical fluid extraction, and pressurized-liquid extraction, are discussed here, in comparison with conventional techniques. The great potentialities of these new innovative green and sustainable approaches are pointed out. Further investigations and optimization are mandatory before their application in industrial processes.
... From an environmental point of view, chemicals from natural sources such as organic acids (Choi et al., 2011), sugars and sweeteners (Carter et al., 2004;Nockemann et al., 2007) and amino acids (Kagimoto et al., 2006), have been considered in DESs composition as starting materials. DESs can be used for many applications including the separation of mixtures (Jiao et al., 2019), desulfurization of fuels (Ahmed Rahma et al., 2017;Li et al., 2019), and extraction of interesting compounds from biological tissues (Benvenutti et al., 2020;Cai et al., 2019;He et al., 2020;Kanberoglu et al., 2019;Ruesgas-Ramón et al., 2020;Saha et al., 2019). ...
Article
Leptospermum scoparium (Manuka) is a small indigenous shrub belonging to the family of Myrtaceae, which is equivalent to a tea tree (Melaleuca alternifolia) in Australia. Manuka leaves are rich in bioactive terpenes such as β-caryophyllene, which are scientifically proven to have potential activities in different areas including antimicrobial, anti-inflammatory, antitumour, antioxidant, and anaesthetic. This research considers for the first time the application of deep eutectic solvents (DESs) as green and sustainable solvents for the extraction of β-caryophyllene (β-CAR) from New Zealand Manuka leaves. The extraction was carried out using twenty-six types of hydrophilic and hydrophobic DESs. Menthol: Lactic acid DES was found to have higher extractability of β-caryophyllene than n-hexane, methanol, and ethanol as reference solvents. Moreover, Menthol: Lactic acid DES at 1:2 molar ratio was more efficient than conventional steam distillation and Soxhlet extraction. Furthermore, β-caryophyllene showed a good stability in menthol: lactic acid DES over 9 days of storage. The final β-caryophyllene concentration (β-CAR= 8.713605 mg/g Manuka leaf) after 4 cycles of extraction suggests a good reusability of the potential DES. The extraction of β-caryophyllene using this DES was further optimised using RSM (response surface methodology) combined with BBD (Box-Behnken design). The optimum experimental conditions were as follows: temperature 25.07 °C, stirring time 1.09 h, and % w/v biomass of 14.99%, which gave an extraction yield of 10.25 mg of β-caryophyllene/g Manuka leaf.
... Due to their excellent properties such as high biodegradability, low toxicity as well as simple and inexpensive preparation, NADESs have already found applications in different research areas, in organic synthesis and biosynthesis (Wu et al., 2019b), electrochemistry (Brett, 2018) and materials science (Tomé et al., 2018). Furthermore, recent publications have shown that NADESs can be successfully used in combination with UAE for the enhanced and greener extraction of phenolics from various matrices: wine less and grape skin (Cvjetko Bubalo et al., 2016), olive pomace (Chanioti and Tzia, 2018), citrus and pomegranate peels (Xu et al., 2019), rosemary (Barbieri et al., 2020), food by-products (Fernández et al., 2018;Ruesgas-Ramón et al., 2020) and others Ş ahin, 2019). Certainly, one of the main advantages of NADESs is their diversity and tunability as they can be prepared by many combinations of hydrogen donor/ hydrogen acceptor pairs, resulting in tailor-made solvents for the selective extraction of the target compound groups (Xu et al., 2019). ...
Article
In the present study, an analytical methodology based on natural deep eutectic solvents (NADESs) and ultrasound-assisted extraction (UAE) is demonstrated as an environmentally friendly protocol for the isolation of valuable phenolic compounds from inflorescences of Helichrysum arenarium L. For this purpose, 11 different NADESs containing choline chloride and selected hydrogen bond donors, including organic acids, polyols, sugars and an amide, were tailored and evaluated based on the content of individual compounds determined by HPLC-PDA-MS n. Choline chloride-lactic acid based NADES (NADES 1) showed the most promising extraction effi-ciencies for flavonoids (15.34 ± 0.10 mg g − 1) and phenolic acids (5.10 ± 0.12 mg g − 1) as the efficiencies were comparable to those obtained with 80 % methanol (15.60 ± 0.09 mg g − 1 and 5.32 ± 0.18 mg g − 1 , respectively) and up to 54 % higher compared to water (9.94 ± 0.13 mg g − 1 and 5.47 ± 0.22 mg g − 1). Furthermore, three essential parameters of the proposed NADES 1 methodology (UAE time, water content in NADES, and NADES hydrogen donor/acceptor molar ratio) were optimized by Box-Behnken experimental design. Based on the statistically evaluated results the following conditions were determined to be optimal: an UAE time of 85 min, 38 % water in NADES 1, and a molar ratio of choline chloride:lactic acid of 1:4. The developed approach allows easy transfer of the proposed methodology to large-scale extraction, enabling clean production with minimal environmental impact.
... Coffee is one of the most popular hot drinks in the world, with three times as much coffee consumed as cocoa and four times as much as tea (Ruesgas-Ramón et al., 2020). In 2016, the coffee yield was 1.60 × 10 8 kg and the export of beans was 8.27 × 10 7 kg (export value of USD 9.04 × 10 8 ) in China (Liu et al., 2018). ...
Article
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Reasonable water and light management technology can improve economic benefits, coffee yield, and quality. We used cluster analysis and principal component analysis to evaluate and optimize the water and light management technology with high coffee yield, quality, and economic benefits in a subtropical monsoon climate region of China. The experiment was arranged in a randomized complete block design with two factors (3 irrigation levels × 4 shade cultivation treatments) replicated four times during 2016–2017. The irrigation levels consisted of full irrigation (FI) and two deficit irrigations (DIL: 75% FI, DIS: 50% FI). The shade cultivation treatments consisted of no shade cultivation (S0) and three shade cultivation modes (SL: intercropping with four lines of coffee and one line of banana; SM: intercropping with three lines of coffee and one line of banana; SS: intercropping with two lines of coffee and one line of banana). The results showed that the effects of irrigation level and shade cultivation mode on growth, crop yield, most of the photosynthetic characteristics, and nutritional quality were significant (p < 0.05). Regression analysis showed that the leaf radiation use efficiency (RUE) showed a significant negative exponential relation or logistic-curve variation with photosynthetically active radiation (PAR). The bean yield increased with an increase of the shade degree when water was seriously deficient, whereas it first increased and then decreased with an increase of the shade degree under FI and DIL. Based on both cluster analysis and principal component analysis, the FISS treatment resulted in the highest comprehensive quality of coffee, followed by the FISM treatment; the DISS0 treatment obtained the lowest quality. Compared with the FIS0 treatment, the FISM treatment increased the 2-year average bean yield and net income by 15.0 and 28.5%, respectively, whereas the FISS treatment decreased these by 17.8 and 8.7%, respectively. To summarize, FISS treatment significantly improved the nutritional quality of coffee, and FISM treatment significantly increased the dry bean yield and economic benefits of coffee. The results of the study could provide a theoretical basis for water-saving irrigation and shade cultivation management of coffee in a subtropical monsoon climate region of China.
... Major flavonoids were identified as quercetin, kaempferol, and myricetin. Very recently, Ruesgas-Ramón et al. [105] used agro-residues from coffee and cocoa industries to recover biomolecules using DESs. The authors reported that the use of lactic acid-ChCl (2:1) provided higher phenolics extraction with ultrasound-probe-assisted extraction than heat stirring-assisted extraction. ...
Chapter
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Lignocellulose is the most abundant component in nature since it refers to plant material. Beyond the enormous utilization of lignocellulose by human being, unignorable amount of waste is also formed simultaneously. Agro-industrial lignocellulosic wastes can cause environmental pollutions if not processed before discharged. An innovative approach for lowering the detrimental influences of lignocellulosic wastes is to consider them as a source of useful products rather than a waste to be decontaminated. Beyond the conventional techniques for evaluation of the wastes, new emerging techniques and the use of new solvents have drawn attention recently. Among new generation solvents, deep eutectic solvents (DESs) have been increasingly used in the treatment of lignocellulosics to produce value-added products such as biofuels, chemicals, and solvents and also used for the recovery of bioactive phenolic compounds. DESs are used extensively for fractionation of lignocellulosic wastes, often in combination with enzymatic hydrolysis of the biomass. On the other hand, extraction and recovery of bioactive compounds are also under research using DESs. This mini review summarizes the very recent literature reports on the use of DESs in treating agro-industrial wastes within the concept of valorization of biomass.
... Caffeine and theobromine were identified in the extracts of coffee pulp and cocoa hush, promising results were obtained using choline chloride: lactic acid:water (1:2:1.5), with yields of 0.53 g of caffeine/100 g of coffee pulp and 0.65 g pf theobromine/100 g cocoa hush, respectively (Ruesgas-Ramón et al., 2020). ...
Article
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A new methodology for the selective extraction of antioxidants from mate tea leaves (and decaffeinated mate tea leaves), using different natural deep eutectic systems (NADES), is reported in this paper. A fractionated extraction was carried out and the optimization of the extraction conditions such as solid/liquid ratio, temperature, time, stirring and the use of ultrasound assisted extraction (UAE) technology was performed. The results demonstrate that a sequential extraction using, in a first step, an hydrophobic system Men:Lau (2:1) and, in a second step, an hydrophilic lactic acid-based NADES, leads to two distinct extracts: the first one rich in pigments and the second one rich in polyphenols. NADES systems were able to extract 30% more of the polyphenolic components of the mate tea leaves matrices, when compared with traditional solvents/techniques. Moreover, it has been shown that the incorporation of the extract in the NADES, compared to the same extract in aqueous medium was beneficial for the stabilization of the antioxidants. It maintains their functionality at least for three months, reaching 41% more versus the extracts obtained by traditional solvents/techniques. The absence of caffeine in the extracts did not shown to have any effects on the stability results.
... There are several methods and procedures to change the composition of the original lignocellulosic matrix aimed at eliminating one of its components (lignin or polysaccharides), thus obtaining new products (pulp, microcrystalline cellulose, nanocellulose etc.), and valorizing the biomass. These include processes such as solubilisation, extraction, fractionation, deconstruction, delignification, and post-delignification [1,13,28,[33][34][35][36][37][38][39][40][41]. Value-added substances and compounds are isolated from biomass by extraction techniques using predominantly water and common organic solvents, and, to a minor extent, eco-friendly green solvents represented by deep eutectic solvents [13]. ...
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Extracts from spruce bark obtained using different deep eutectic solvents were screened for their total phenolic content (TPC) and antioxidant activities. Water containing choline chloride-based deep eutectic solvents (DESs) with lactic acid and 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, and 1,5-pentanediol, with different molar ratios, were used as extractants. Basic characteristics of the DESs (density, viscosity, conductivity, and refractive index) were determined. All the DESs used behave as Newtonian liquids. The extractions were performed for 2 h at 60 °C under continuous stirring. TPC was determined spectrophotometrically, using the Folin-Ciocalteu reagent, and expressed as gallic acid equivalent (GAE). The antioxidant activity was determined spectrophotometrically by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. The TPC varied from 233.6 to 596.2 mg GAE/100 g dry bark; radical scavenging activity (RSA) ranged between 81.4% and 95%. This study demonstrated that deep eutectic solvents are suitable solvents for extracting phenolic compounds from spruce bark.
... It observed that lactic acid:choline chloride (2:1 mol ratio) was the most promising DES. It also found a higher extraction yield using ultrasound-probe assisted extraction at 200 W than the heat stirringassisted extraction (Ruesgas-Ramón et al., 2020). A series of DESs (e.g. ...
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In this chapter, the main approach is focusing on the biorefinery of the different structural layers of coffee waste, rather than selecting a main type of waste. Through this attempt, a circular economy with financial and environmental impacts can be achieved with implications for the coffee industry at different levels. Therefore the use of coffee waste is based on its promising chemical composition, as described in the next section, which can contribute to a sustainable development by means of obtaining high value-added products, which are explored in this chapter.
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Coffee pulp contains natural antioxidants like hydroxycinnamic acids, most of which are covalently linked to the cell wall. These compounds can be released by fermentation or enzymatic processes. In this study, the antioxidant properties of fermented and nonfermented coffee pulp have been evaluated. Coffee pulp was fermented by solid-state fermentation using the fungus Aspergillus tamarii. Fermented and nonfermented samples of coffee pulp were extracted with aqueous methanol followed by alkaline hydrolysis. In both cases, the total polyphenol concentration was quantified by Folin-Ciocalteu method, then hydroxycinnamic acids were concentrated using ethyl acetate and quantified by HPLC. The antioxidant properties of samples were determined by radical monocation of 2,2’-azinobis-( 3-ethylbenzothiazoline-6-sulphonic acid) [ABTS]·+: the antioxidant activity was determined by kinetic parameters known as ED50, tED50 and antiradical efficiency (AE). Fermented extracts containing free hydroxycinnamic acids showed better antiradical activity against [ABTS]·+ than the other nonfermented ones. There were no significant differences in the total content of polyphenols in fermented and nonfermented coffee pulp, but the content of total hydroxycinnamic acids was higher in the nonfermented coffee pulp extracts (47.1 g/kg) than in the fermented coffee pulp (30.9 g/kg). Nevertheless, the fermentation process increased the fraction of free hydroxycinnamic acids (47 %) and consequently decreased those covalently linked to the cell wall. The results of the antioxidant activity assays could be explained by the presence of free hydroxycinnamic acids. Fermented coffee pulp assays showed that free hydroxycinnamic acids were metabolised by A. tamarii. This study shows the potential of using coffee pulp as a natural source of antioxidants.
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Recently, furfural, “the sleeping beauty bio-renewable chemical” has gained a renewed attention as a potential chemical for the production of biofuels and biochemicals. Furfural is the most commonly produced industrial chemical because its production is very flexible. It is one of the top value-added chemicals that can be produced from biomass. Furfural and its derivatives have been extensively used in plastics, pharmaceutical and agrochemical industries. Furfural is a natural precursor to a range of furan-based chemicals and solvents such as dihydropyran, methyltetrahydrofuran, tetrahydrofuran, methylfuranfurfuryl alcohol, tetrahydrofurfuryl alcohol and furoic acid. Furfural and its derivatives have been widely applied as fungicides and nematicides, transportation fuels, gasoline additives, lubricants, resins, decolorizing agents, jet fuel blend stocks, drugs, insecticides, bio-plastics, flavor enhancers for food and drinks, rapid all-weather repair system for bomb-damaged runways and pot holes and also for wood modification and book preservation.
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The present investigation demonstrated pretreatment of lignocellulosic biomass rice straw using natural deep eutectic solvents (NADESs), and separation of high-quality lignin and holocellulose in a single step. Qualitative analysis of the NADES extract showed that the extracted lignin was of high purity (>90 %), and quantitative analysis showed that nearly 60 ± 5 % (w/w) of total lignin was separated from the lignocellulosic biomass. Addition of 5.0 % (v/v) water during pretreatment significantly enhanced the total lignin extraction, and nearly 22 ± 3 % more lignin was released from the residual biomass into the NADES extract. X-ray diffraction studies of the untreated and pretreated rice straw biomass showed that the crystallinity index ratio was marginally decreased from 46.4 to 44.3 %, indicating subtle structural alterations in the crystalline and amorphous regions of the cellulosic fractions. Thermogravimetric analysis of the pretreated biomass residue revealed a slightly higher T dcp (295 °C) compared to the T dcp (285 °C) of untreated biomass. Among the tested NADES reagents, lactic acid/choline chloride at molar ratio of 5:1 extracted maximum lignin of 68 ± 4 mg g(-1) from the rice straw biomass, and subsequent enzymatic hydrolysis of the residual holocellulose enriched biomass showed maximum reducing sugars of 333 ± 11 mg g(-1) with a saccharification efficiency of 36.0 ± 3.2 % in 24 h at 10 % solids loading.
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This study presents a review of the Folin-Ciocalteu (F-C) assay for total phenolic content (TPC) determinations and describes different approaches to improve its specificity. Phenolics are regarded as the molecules with the highest potential to neutralize free radicals. Therefore, their quantification is a common practice in different areas of food research. However, when determining TPC in plant food extracts, the presence of reducing interferants [ascorbic acid (AA)] produces inaccurate estimations of TPC values. Different methodologies have been proposed to improve the specificity of the F-C assay. These methodologies include: (i) the use of solid phase extraction (SPE) cartridges to separate interferants from phenolics; (ii) the calculation of a corrected TPC value based on the AA reducing activity present in the extract; and (iii) the pre-treatment of extracts with oxidative agents prior to TPC quantification. These methods are described in detail in the present study. Likewise, their advantages and disadvantages are discussed based on new experimental data. A simple modification of the F-C assay procedure is proposed to quantify both the TPC value and the AA reducing activity in plant food extracts. Values obtained by the modified F-C assay can be used to estimate a corrected TPC value.
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Green and efficient extraction of natural products from biomass is considered an important field in the pharmaceutical and biochemical industries. Recently, deep eutectic solvents (DESs) have been growing in interest as sustainable and safe solvents. In this study, we aimed to provide a practical example using a popular traditional Chinese medicine, Flos sophorae, showcasing the tuneability of DESs as designer solvents to selectively and efficiently extract bioactive compounds from biomass. As a result, a solvent called PG-1 that was tailor-made from a 2:5 mixture of L-proline and glycerol using freeze-drying method, was more effective than methanol for extraction of quercetin, kaempferol, and isorhamnetin glycosides from Flos sophorae. With PG-1-based ultrasound-assisted extraction (UAE), operational conditions including the DES content in the extractant, extractant-to-sample solid ratio, and ultrasound irradiation time for UAE were statistically optimized using a central composite design combined with response surface methodology. The resulting extraction method in which 50 mg of sample powder was extracted by UAE for 45 min using 1.00 mL of aqueous solution containing 90% w/w PG-1 was found to be a greener and more efficient process than common extraction methods such as methanol-based UAE and heat reflux extraction that are generally environmentally harmful. Based on the antioxidant activity measured by DPPH assay, the tailor-made extractant exhibited additive activity arising from its component, L-proline. Recovery of extracted flavonoids from the DES, which was assessed from rutin, since it is the major flavonoid extracted, was 75% with the use of water as an anti-solvent, and could reach as high as 92% with the simple application of C18 solid phase extraction (SPE). In comparison, the recovery efficiency of the anti-solvent method was significantly reduced for the flavonoid glycosides from the real Flos sophorae extracts, while the efficiency of the SPE method was reasonably high (81-87%). The present study suggests that DESs are truly designer solvents that can be used as sustainable and safe extraction media for pharmaceutical and biochemical applications.
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Spent coffee grounds (SCGs) are viewed as a valuable resource for useful bioactive compounds, such as chlorogenic acids and flavonoids, and we suggest an eco-friendly and efficient valorization method. A series of choline chloride-based deep eutectic solvents (DESs) were tested as green extraction solvents for use with ultrasound-assisted extraction. Extraction efficiency was evaluated based on total phenolic content (TPC), total flavonoid content, total chlorogenic acids, and/or anti-oxidant activity. A binary DES named HC-6, which was composed of 1,6-hexanediol:choline chloride (molar ratio 7:1) was designed to produce the highest efficiency. Experimental conditions were screened and optimized for maximized efficiency using a two-level fractional factorial design and a central composite design, respectively. As a result, the proposed method presented significantly enhanced TPC and anti-oxidant activity. In addition, phenolic compounds could be easily recovered from extracts at high recovery yields (>90%) by adsorption chromatography.
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Sustainable solvents are a topic of growing interest in both the research community and the chemical industry due to a growing awareness of the impact of solvents on pollution, energy usage, and contributions to air quality and climate change. Solvent losses represent a major portion of organic pollution, and solvent removal represents a large proportion of process energy consumption. To counter these issues, a range of greener or more sustainable solvents have been proposed and developed over the past three decades. Much of the focus has been on the environmental credentials of the solvent itself, although how a substance is deployed is as important to sustainability as what it is made from. In this Review, we consider several aspects of the most prominent sustainable organic solvents in use today, ionic liquids, deep eutectic solvents, supercritical fluids, switchable solvents, liquid polymers, and renewable solvents. We examine not only the performance of each class of solvent within the context of the reactions or extractions for which it is employed, but also give consideration to the wider context of the process and system within which the solvent is deployed. A wide range of technical, economic, and environmental factors are considered, giving a more complete picture of the current status of sustainable solvent research and development.
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Is hydration the solution to the viscosity of deep eutectic solvents (DESs)? In their Communication (DOI: 10.1002/anie.201702486), K. J. Edler and co-workers determine the nanostructure of DES/water mixtures over a wide hydration range by neutron diffraction and atomistic modeling. The mixture retains the characteristics of the DES structure up to remarkably high water levels and is then converted into a state best described as a simple aqueous solution of the DES molecular components.
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Cocoa shell is removed from the cocoa bean before or after the seeds are roasted; it is considered a by-product of the cocoa industry that is usually underutilized or considered waste. Some studies and patents have been developed in order to give a nobler destination to this material. Interest in cocoa shell is due to its high nutritional value owing to the presence of a variety of biocompounds, such as phenolic compounds, dietary fibers, theobromine and a lipid profile similar to that of cocoa butter, besides its chocolate color and flavor.
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The disintegration of orange peel waste in deep eutectic solvents and diluted organic acids is presented in this work. The albedo and flavedo layers of the peel were studied separately, showing faster disintegration of the latter. Addition of water to the deep eutectic solvents lowered the amount of remaining solids and improved the disintegration times. These improvements are subscribed to a decrease in viscosity upon deep eutectic solvent dilution. Each of the individual deep eutectic solvent components were diluted and subjected to the same disintegration tests. The corresponding diluted organic acids showed similar orange peel disintegration performance as the tested deep eutectic solvents, whereas dilutions of the other counterparts did not show any activity. Hence, the active deep eutectic solvent components during orange peel treatment are considered to be their organic acids. Flavonoids and essential oils were released during the treatment, offering new opportunities for the development of orange peel waste valorisation routes.
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Cocoa crops development presents challenges concerning the proper disposal of waste generated by this activity, and the obtaining of value-added products. Thus, the aim of this study was to obtain pectin from cocoa pod husk (Theobroma cacao L.). Infrared spectrum results showed peaks of galacturonic acid functional groups, indicating the presence of pectin in the cocoa husk. In extraction stage was carried out acid hydrolysis with citric or acetic acid at different pH (2, 2.5 and 3), 90°C temperature and 90 minutes, and was evaluated its influence on yield, methoxyl and galacturonic acid content. From the established extraction conditions, aqueous citric acid at pH 2.0 provided the highest yield and methoxyl content, 18.12% and 15.5% respectively. While the galacturonic acid content showed better results with acetic acid at pH 3 with an 83.1%. Finally, it was concluded that cocoa pod husks are suitable to obtain pectin, and a marked influence of the type of acid on response variables in the pectin extraction process was observed.
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In this Minireview, the state of the art in the use of ionic liquids (ILs) and deep eutectic solvents (DESs) as alternative reaction media for biocatalytic processes and biomass conversion is presented. Initial, proof-of-concept studies, more than a decade ago, involved first-generation ILs based on dialkylimidazolium cations and non-coordinating anions, such as tetrafluoroborate and hexafluorophosphate. More recently, emphasis has switched to more environmentally acceptable second-generation ILs comprising cations, which are designed to be compatible with enzymes and, in many cases are derived from readily available, renewable resources, such as cholinium salts. Protic ionic liquids (PILs), prepared simply by mixing inexpensive amines and acids, are particularly attractive from both an environmental and economic viewpoint. DESs, prepared by mixing inexpensive salts with, preferably renewable, hydrogen-bond donors such as glycerol and amino acids, have also proved suitable reaction media for biocatalytic conversions. A broad range of enzymes can be used in ILs, PILs and DESs, for example lipases in biodiesel production. These neoteric solvents are of particular interest, however, as reaction media for biocatalytic conversions of substrates that have limited solubility in common organic solvents, such as carbohydrates, nucleosides, steroids and polysaccharides. This has culminated in the recent focus of attention on their use as (co)solvents in the pretreatment and saccharification of lignocellulose as the initial steps in the conversion of second-generation renewable biomass into biofuels and chemicals. They can similarly be used as reaction media in subsequent conversions of hexoses and pentoses into platform chemicals.
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This paper reports a new method of applying Deep Eutectic Solvents (DES) for extracting lignin from woody biomass with high yield and high purity. DES mixtures prepared from Choline Chloride (ChCl) and four hydrogen-bond donors–acetic acid, lactic acid, levulinic acid and glycerol–were evaluated for treatment of hardwood (poplar) and softwood (D. fir). It was found that these DES treatments can selectively extract a significant amount of lignin from wood with high yields: 78% from poplar and 58% from D. fir. The extracted lignin has high purity (95%) with unique structural properties. We discover that DES can selectively cleave ether linkages in wood lignin and facilitate lignin removal from wood. The mechanism of DES cleavage of ether bonds between phenylpropane units was investigated. The results from this study demonstrate that DES is a promising solvent for wood delignification and the production of a new source of lignin with promising potential applications.
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Deep eutectic solvents (DESs) are emerging as green and sustainable solvents for efficient extraction of bioactive compounds or drugs. This work aimed to comprehensively evaluate the potential and effectiveness of DESs for extraction of different types of natural compounds from biomass. Five Chinese herbal medicines including Berberidis Radix, Epimedii Folium, Notoginseng Radix et Rhizoma, Rhei Rhizoma et Radix, and Salviae Miltiorrhizae Radix et Rhizoma were selected to assess the efficiency of DESs on extraction of alkaloids, flavonoids, saponins, anthraquinones, and phenolic acids, respectively. Totally 43 types of choline chloride-, betaine- and L-proline-based DESs with different polarity, viscosity, composition, and solubilization abilities were tailored to test their extraction efficiency, and the operation conditions were statistically optimized using response surface methodology to produce the most efficient process. In this work, DES solvents were firstly introduced to extract alkaloids and anthraquinones. The results indicated that most prepared DESs proved to be efficient solvents for extraction of alkaloids, but lower extractability for anthraquinones. The extraction capacity of DES may be correlated with their physical-chemical properties, including H-bonding interactions, polarity, viscosity and pH. This study demonstrated that DESs were suitable green extraction solvents for selectively and efficiently extracting bioactive compounds from biomaterials.
Chapter
At the coffee production sites (farms and estates), two different main methods of processing are used to obtain intermediate products that will subsequently be treated in exactly the same way to provide the coffee beans of commerce. These methods are dry processing, which produces dried cherry coffee and wet processing, which produces (dry) parchment coffee. Dry processing is generally used for robusta coffee, but is also used in Brazil for the majority of arabica coffees. Wet processing, on the other hand, is used for arabica and results in so-called mild coffee, when fermentation is included in the preparation process. Dry processing is very simple and, most important of all, is less demanding in respect of harvesting, since all the berries or cherries are dried immediately after harvest. In contrast, wet processing requires more strict control of the harvesting as unripe berries or berries that have partly dried on the tree cannot be handled by the pulping machines.
Article
In this study, a deep eutectic solvent based microwave assisted extraction (DES-MAE) method was developed. This method was used for the extraction of five target phenolic acids, namely chlorogenic acid, caffeic acid, 3,5-dicaffeoylquinic acid, 3,4-dicaffeoylquinic acid, and 4,5-dicaffeoylquinic acid from Lonicerae japonicae Flos. Twelve kinds of aqueous deep eutectic solvents were investigated. The results indicated that deep eutectic solvents (DESs) showed remarkable effects on the extraction efficiency of phenolic acids. In addition, the parameters of DES-MAE, including concentration of water in DES, liquid/solid ratio, extraction temperature, and extraction time were optimized. The proposed approach was evaluated by comparison with the conventional heat-reflux extraction (HRE) and ultrasound assisted extraction (UAE). Finally, the recovery of active compounds from DES was also investigated. Recovery rates of chlorogenic acid, caffeic acid, 3,4-dicaffeoylquinic acid, 3,5-dicaffeoylquinic acid, and 4,5-dicaffeoylquinic acid reached 79.25%, 80.03%, 85.96%, 86.01% and 85.52%, respectively.
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Transformation of the hemicellulose fraction in an environmentally benign manner to deliver high value-added chemicals is critical for the integrated utilization of biomass. Amongst all the chemicals derived from hemicellulose, furfural (produced by hydrolysis of xylan into xylose and successive dehydration of the latter) is a promising option. In this manuscript, a catalytic approach for converting xylan and xylose into furfural co-catalyzed by choline chloride-citric acid H2O, a deep eutectic solvent (DES) synthesized from biorenewable building blocks, and trivalent metal chloride was developed. Choline chloride-citric acid H2O acted as both reaction medium and Brønsted acid catalyst. Both monophasic route and biphasic route (with methyl isobutyl ketoneas extractant for in situ extraction of furfural) were proposed. The highest furfural yields obtained from xylose and xylan in monophasic approach were 59.3% and 54.2%, respectively, at 140 °C, and these values increased to 73.1% and 68.6% when biphasic system was applied for the reaction. Moreover, in biphasic system, choline chloride-citric acid and metal chloride could be recycled and reused for 5 runs with stable catalytic ability.
Article
In the present study, deep eutectic solvents (DESs) as new extraction solvents, are proposed for the green and efficient extraction and separation of bioactive flavonoids from Equisetum palustre L. with negative pressure cavitation-assisted extraction (NPCE) combined with macroporous resin enrichment. A series of different DES systems were investigated for the extraction of bioactive flavonoids in E. palustre. Compared with conventional extraction solvents, DES composed of choline chloride/betaine hydrochloride-ethylene glycol possessed a more effective extraction yields. In addition, the DES-NPCE extraction procedures were also optimized systematically. The optimal conditions were obtained as follows: choline chloride-betaine hydrochloride-ethylene glycol formed a DES with the mole ratio of 1:1:2, 20% water content, extraction pressure −0.07 MPa, extraction temperature 60°C, solvent to solid ratio 25:1 mL/g, and the extraction time 20 min. Furthermore, the direct enrichment of nine flavonoids in DES extraction solution were efficiently achieved using macroporous resin HPD-826. The contents of the nine target flavonoids separated by HPD-826 resin were from 0.17% to 3.37%, and the recovery yields from 57.14% to 89.25%. In conclusion, the developed DES-NPCE combined with macroporous resin enrichment can be an alternative procedure for the green and efficient extraction and separation of bioactive flavonoids from plant sample matrices.
Article
A certain combination of natural products in the solid state becomes liquid, so called natural deep eutectic solvents (NADES). Recently, they have been considered promising new green solvents for foods, cosmetics and pharmaceuticals due to their unique solvent power which can dissolve many non-water-soluble compounds and their low toxicity. However, in addition to the features as solvents, the stabilisation ability of NADES for compounds is important for their further applications. In the study, the stability analysis demonstrates that natural pigments from safflower are more stable in sugar-based NADES than in water or 40% ethanol solution. Notably, the stabilisation capacity of NADES can be adjusted by reducing water content with increasing viscosity. The strong stabilisation ability is due to the formation of strong hydrogen bonding interactions between solutes and NADES molecules. The stabilising ability of NADES for phenolic compounds shows great promise for their applications in food, cosmetic and pharmaceutical industries.
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Several methods have been described for the determination of phenolic compounds in animal and plant products using the Folin-Ciocalteu (FC) assay. Most of these methods describe the use of this reagent and sodium carbonate in spectrophotometric methods. The macro FC assay was compared with two micro FC assays carried out on a microplate reader. Excellent correlation was obtained among the three assays with a molar extinction coefficient of 5.228±0.187x103 M−1 cm−1. The micro assay may serve as a high throughput method for the rapid determination of polyphenols in various samples.
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The composition of cacao pod husks (CPHs), the main waste product of cocoa production, and some of the characteristics of their water-soluble pectins were investigated. Milled and dried CPHs were submitted to hot aqueous extractions (50 and 100̊C, 90min, 1:25, w/v). The obtained fractions (labeled 50W and BW, respectively) yielded 7.5 and 12.6% pectins, respectively. The monosaccharide composition revealed the predominance of uronic acid, followed by galactose, rhamnose and arabinose, characteristic of pectins. Chemical and spectroscopic analyses (FT-IR and 13C NMR) showed that both fractions contained high acetyl contents (DA 29.0 and 19.2%, respectively) and are composed of low methoxyl homogalacturonans (DE 37.0 and 42.3%, respectively) with rhamnogalacturonan insertions carrying side chains containing mainly galactose. Rheological analyses were carried out with 50W and BW. Solutions of both fractions at 5% (w/v) had a non-Newtonian shear-thinning behavior, however that of 50W showed higher apparent viscosity than that of BW. Dynamic oscillatory analyses showed that 5% (w/w) 50W pectin had weak gel behavior whereas at the same concentration, BW pectin behaved as a concentrated solution. Although further investigations are required, CPH seems be a potential source of both pectins and other natural agents such as fibers and phenolics, and its use is particularly justified by growing environmental awareness.
Article
Rationale: In order to deepen the understanding of electrospray ionisation collision-induced dissociation (ESI-CID) fragmentation reactions of xanthine derivatives for the identification of metabolites using low-resolution liquid chromatography/mass spectrometry (LC/MS) analysis, basic experiments using caffeine (1,3,7-trimethylxanthine) as model compound have been performed. Methods: Six deuterium isotopomers and one N1-ethylated homologue of caffeine have been synthesized and their ESI fragmentation spectra have been obtained by using LC/MS in combination with either standard or perdeuterated eluent mixtures. Results: One result of these studies is the finding that the positive charges of the ESI-CID caffeine fragments are caused by the addition of protons. Furthermore, the performed experiments allow the determination of all molecular formulae of each ESI-CID caffeine fragment. Conclusions: As basic CID reactions of caffeine have been elucidated in this work, the developed fragmentation scheme may serve as a valuable tool for the interpretation of ESI-CID fragmentation spectra of more complex xanthine derivatives and their respective metabolites.
Article
This paper describes the chemical characterization of cocoa hulls, a potential source of high-methoxyl pectins (HMP). The content of some antinutritive compounds and potentially toxic compounds is also reported. Use of 2-propanol is proposed for the preliminary clean-up of the hulls and for the washing of the gel. Antinutritive and potentially toxic compounds seem not to limit the use of cocoa hulls. Lindane and ochratoxin A were easily removed together with fat using 2-propanol during preliminary clean up. The pectins (partially purified, yield: 1.29 0.08%) showed a high methoxylation degree (%DE) of 60.53 6.09%, and a viscosity of 16,200 cPs (5 rpm 20 °C). Washing procedures permit the decrease of the gel acidity from pH 1.97 to pH 3.76.
Article
Methanolic extracts of low-grade green coffee beans (LCB) and spent coffee were analysed for radical-scavenging activity (α,α-diphenyl-β-picrylhydrazyl radical) and oxygen radical absorbance capacity (ORAC). The extracts were also evaluated for anti-tumour (P388 cell assay), anti-inflammatory (J774A.1 cell assay) and anti-allergenic (RBL-2H3 cell line) activities in vitro. LCB extract was found to exhibit a radical-scavenging activity of 92.0% followed by spent Arabica (86.9%) and spent Robusta (82.0%) at a concentration of 50 ppm. The antioxidant activity of LCB extract, measured as Trolox equivalents (4416 μM/g) was significantly (p < 0.05) higher than that of the spent coffee extracts. However, extracts of spent coffee exhibited significantly (p < 0.05) more anti-tumour activity than the LCB extract in terms of cell viability. This could be due to the possible role of brown pigments (melanoidins and phenolic polymers), formed during roasting, which may protect cells from oxidative damage in the biological system. However, both the extracts of LCB and spent coffee showed limited anti-inflammatory and anti-allergic activities. The presence of phenolics and chlorogenic acids in appreciable quantities along with brown pigments makes these coffee by-products a source for natural antioxidants.
Article
The contents of low molecular mass phenols and caffeine have been analysed in five samples of beans and the associated pulp, derived from two species of coffee and two associated hybrids. The composition of the coffee beans was consistent with previous reports. The pulp contained smaller quantities of the same caffeoylquinic acids, feruloylquinic acids and dicaffeolyquinic acids as the beans, but caffeoylferuloylquinic acids were not found even in the pulp from a robusta coffee. Pulp from a robusta coffee had a lower caffeine content than the pulp from two arabica cultivars, the reverse of the situation existing in the beans. A significant component in all pulp samples was isolated and identified as protocatechuic acid.
Article
An activity-directed fractionation and purification process was used to isolate 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) scavenging components from Juglans regia kernels. Ethyl acetate and n-butanol fractions showed greater DPPH scavenging activities compared to those of water and petroleum ether fractions. The ethyl acetate fraction was subjected to purification using column chromatography. Seven phenolic compounds, pyrogallol (1), p-hydroxybenzoic acid (2), vanillic acid (3), ethyl gallate (4), protocatechuic acid (5), gallic acid (6) and 3,4,8,9,10-pentahydroxydibenzo[b,d]pyran-6-one (7), containing significant antioxidant activities were isolated and identified in J. regia by spectroscopic methods for the first time in this study. The relative order of DPPH scavenging capacity for these compounds was 7 > 6 ⩾ 4 ⩾ 1 > Trolox ⩾ 5 > 3 > 2. The results of this study suggested that the antioxidant activities of these phenolic compounds may be influenced by the number of hydroxyls in their aromatic rings.