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Special Issue "Green Extraction, Separation and Purification Processes"

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Green Chemistry".

Deadline for manuscript submissions: 30 June 2019

Special Issue Editors

Guest Editor
Prof. Dr. Elena Ibáñez

Laboratory of Foodomics, CIAL, CSIC, Nicolas Cabrera 9, 28049 Madrid, Spain
Website | E-Mail
Interests: green extraction processes; green foodomics; bioactives; sustainability; biorefinery; food by-products valorization; compressed fluids; supercritical fluid extraction; pressurized liquid extraction; subcritical water; gas-expanded liquids; advanced analytical techniques; gas chromatography; liquid chromatography; supercritical fluid chromatography; mass spectrometry; agricultural by-products; food wastes; plants; algae
Guest Editor
Prof. Dr. Farid Chemat

Université d´Avignon et des Pays du Vaucluse, France
Website | E-Mail
Phone: 0033490144465

Special Issue Information

Dear Colleagues.

Green chemistry “based on natural products” is a new concept that meets the challenges of the twenty-first century, protecting both environment and consumers, and, at the same time, enhancing knowledge of research and the competitiveness of industries, by becoming more ecologic, economic, and innovative and therefore sustainable. It is based on the discovery and design of extraction, separation, purification and hemi-synthesis processes, which reduce energy consumption, allow the use of alternative solvents and renewable natural products, and ensure a safe and high-quality final product.

The present Special Issue, “Green Extraction, Separation and Purification Processes”, aims to collect and publish recent advances in this interdisciplinary area. Reviews and research articles dealing with innovative techniques, alternative solvents, original procedures, comprehension of intensification mechanisms, by product valorization, and green impacts and sustainable footprints, starting from production and harvesting of the plant, the transformation processes, solid–liquid extraction, and also separation and purification, together with formulation and hemi-synthesis are welcome. In term of dissemination, this Special Issue is aiming to provide some guidelines for good practice and reporting in several areas: Analytical chemistry, natural product chemistry, food processing, pharmaceutical chemistry, agricultural products, functional foods, nutraceuticals, cosmetics, bioeconomy, etc.

Prof. Dr. Elena Ibañez
Prof. Dr. Farid Chemat
Guest Editors

Manuscript Submission Information

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Keywords

  • Extraction solid–liquid and liquid–liquid
  • separation
  • purification
  • intensification
  • integration
  • enabling technologies
  • natural products
  • compressed fluids (sub- and supercritical)
  • microwave
  • ultrasound
  • hemi-synthesis
  • biorefinery
  • valorization
  • industrial by-products
  • life cycle assessment

Published Papers (13 papers)

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Research

Open AccessArticle
Development of a Green Downstream Process for the Valorization of Porphyridium cruentum Biomass
Molecules 2019, 24(8), 1564; https://doi.org/10.3390/molecules24081564
Received: 3 April 2019 / Revised: 17 April 2019 / Accepted: 18 April 2019 / Published: 20 April 2019
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Abstract
As the interest in biorefinery approaches is continuously increasing, new alternatives for the downstream valorization of biomasses are sought. Porphyridium cruentum microalga is a good natural source for a variety of interesting bioactive compounds, including carotenoids, phycoerythrin, and sulfated polysaccharides. In the present [...] Read more.
As the interest in biorefinery approaches is continuously increasing, new alternatives for the downstream valorization of biomasses are sought. Porphyridium cruentum microalga is a good natural source for a variety of interesting bioactive compounds, including carotenoids, phycoerythrin, and sulfated polysaccharides. In the present contribution, the use of compressed fluids-based techniques is explored towards the efficient and green extraction of bioactive compounds to valorize microalgal biomass. The extraction of carotenoids was first optimized using pressurized ethanol. The best extraction conditions involved the use of 125 °C for 20 min at 10.5 MPa. Subsequently, a sequential valorization process was devised based on the application of different steps directed towards the extraction of phycoerythrin, sulfated polysaccharides, and carotenoids, respectively. The applied pressurized conditions allowed the attainment of a good recovery of polar components without compromising the stability and extraction of carotenoids. Therefore, the proposed approach could be employed to obtain different bioactives from P. cruentum microalgal biomass employing green extraction processes. Full article
(This article belongs to the Special Issue Green Extraction, Separation and Purification Processes)
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Open AccessArticle
Structural and Rheological Properties of Pectins Extracted from Industrial Sugar Beet By-Products
Molecules 2019, 24(3), 392; https://doi.org/10.3390/molecules24030392
Received: 14 December 2018 / Revised: 14 January 2019 / Accepted: 17 January 2019 / Published: 22 January 2019
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Abstract
In this work, the efficient extraction of pectin from sugar beet by-products (pressed, ensiled and dried pulp), by using an acid method or a commercial cellulose, is accomplished. The extraction method had an impact on the pectin monomeric composition, mainly in xylose, arabinose, [...] Read more.
In this work, the efficient extraction of pectin from sugar beet by-products (pressed, ensiled and dried pulp), by using an acid method or a commercial cellulose, is accomplished. The extraction method had an impact on the pectin monomeric composition, mainly in xylose, arabinose, and galacturonic acid content, as determined by GC-FID. FTIR and SEC analyses allowed the determination of similar degrees of methoxylation and molecular weights, respectively, in the extracted pectins. The acid extraction of pectin in the ensiled by-product led to the highest yield (19%) with a galacturonic acid content of 46%, whereas the application of the enzymatic extraction method resulted in a lower yield (13%) but higher galacturonic acid content (72%). Moreover, the stability in aqueous solution as well as the emulsifying activity index was higher for pectin extracted by the acid method, whereas the viscosity was higher in pectin extracted by the enzymatic method. To the best of our knowledge, this is the first study analyzing the physicochemical properties and exploring the potential reuse of ensiled and dried by-products from sugar beet industry for the extraction of pectin to be further used in the food and pharmaceutical areas. Full article
(This article belongs to the Special Issue Green Extraction, Separation and Purification Processes)
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Open AccessArticle
Green Extraction of Six Phenolic Compounds from Rattan (Calamoideae faberii) with Deep Eutectic Solvent by Homogenate-Assisted Vacuum-Cavitation Method
Molecules 2019, 24(1), 113; https://doi.org/10.3390/molecules24010113
Received: 28 November 2018 / Revised: 20 December 2018 / Accepted: 25 December 2018 / Published: 29 December 2018
Cited by 1 | PDF Full-text (3970 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A homogenate-assisted vacuum-cavitation extraction (HVE) method with a “green” solvent (a deep eutectic solvent, DES) was developed to extract phenolic compounds from rattan (Calamoideae faberii). In this study, the optimum molar ratio of choline chloride (ChCl) and ethylene glycol (EG) was [...] Read more.
A homogenate-assisted vacuum-cavitation extraction (HVE) method with a “green” solvent (a deep eutectic solvent, DES) was developed to extract phenolic compounds from rattan (Calamoideae faberii). In this study, the optimum molar ratio of choline chloride (ChCl) and ethylene glycol (EG) was 1:3, the optimum volume ratio of ChCl-EG:H2O was 6:4, the solid-liquid ratio of HVE was 1:15, and the extraction time of homogenate and vacuum-cavitation were 2.0 min and 25 min, respectively. Under the optimum parameters of HVE, the extraction yield of total phenolic content with ChCl-EG solution was 6.82 mg/g. The higher total phenolic content was detected in fruit tissues (seeds 81.24 ± 1.55 mg/g, episperm 43.21 ± 0.87 mg/g, and arillus 38.47 ± 0.74 mg/g), followed by in leaves (sheath 19.5 ± 0.38 mg/g and blade 17.81 ± 0.33 mg/g). In addition, the content of specific phenolic compounds in aqueous and DES extracts was determined. Chlorogenic acid was the most abundant phenol in most organs of the rattan plant. Gallic acid was mainly distributed in the arillus; protocatechuic acid was mainly distributed in the arillus, sheath, and blade; protocatechuic aldehyde was mainly distributed in the blade, seed, and sheath; (+)-catechins were mainly distributed in the episperm, seed, and sheath; and epigallocatechin gallate was mainly distributed in the blade. The recovery rates of gallic acid, protocatechuic acid, protocatechuic aldehyde, (+)-catechins, chlorogenic acid, and epigallocatechin gallate were 93.77%, 94.09%, 97.32%, 97.83%, 94.41%, and 92.47%, respectively, by AB-8 resin. Full article
(This article belongs to the Special Issue Green Extraction, Separation and Purification Processes)
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Open AccessArticle
Supercritical CO2 Extraction of Eruca sativa Using Cosolvents: Phytochemical Composition by LC-MS Analysis
Molecules 2018, 23(12), 3240; https://doi.org/10.3390/molecules23123240
Received: 10 November 2018 / Revised: 30 November 2018 / Accepted: 4 December 2018 / Published: 7 December 2018
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Abstract
Background: Eruca sativa Mill. is a good source of glucosinolates (GLS), phenolic compounds and unsaturated fatty acids, being a valuable material for the production of functional-foods or nutraceutical ingredients. Extraction by supercritical CO2 (SCO2) can be used and the limitations [...] Read more.
Background: Eruca sativa Mill. is a good source of glucosinolates (GLS), phenolic compounds and unsaturated fatty acids, being a valuable material for the production of functional-foods or nutraceutical ingredients. Extraction by supercritical CO2 (SCO2) can be used and the limitations due to the apolar nature of CO2 can be overcome using co-solvents. In this paper different cosolvents and conditions were used for SCO2 extraction and the composition of the obtained extracts was studied by LC-MS. Results: Water resulted the ideal co-solvent, allowing the extraction of glucosinolates in comparable amounts to the classical procedure with boiling water, as it can be carried out at mild temperatures (45 °C vs. >100 °C). Increasing the pressure improved the GLS extraction. On the other hand polyphenol extraction under the studied conditions was not influenced by pressure and temperature variations. The in vitro antioxidant effect of the obtained extracts was also measured, showing significant activity in the DPPH and FC tests. Conclusions: The GLS, flavonoids and lipids composition of the obtained extracts was studied, showing the presence of numerous antioxidant constituents useful for nutraceutical applications. The extraction method using SCO2 and water as co-solvent presents advantages in terms of safety because these solvents are generally recognised as safe. Water as cosolvent at 8% resulted useful for the extraction of both glucosinolates and phenolics in good amount and is environmentally acceptable as well as safe for food production. Full article
(This article belongs to the Special Issue Green Extraction, Separation and Purification Processes)
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Open AccessArticle
Extraction of Triterpenic Acids and Phytosterols from Apple Pomace with Supercritical Carbon Dioxide: Impact of Process Parameters, Modelling of Kinetics, and Scaling-Up Study
Molecules 2018, 23(11), 2790; https://doi.org/10.3390/molecules23112790
Received: 21 September 2018 / Revised: 19 October 2018 / Accepted: 23 October 2018 / Published: 27 October 2018
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Abstract
Apple pomace, a byproduct of juice production, is a rich source of bioactive compounds and nutrients. Supercritical fluid extraction was proposed as a method for a fast and selective extraction of hydrophobic compounds with a pharmaceutical potential from this matrix. Chromatographic analysis showed [...] Read more.
Apple pomace, a byproduct of juice production, is a rich source of bioactive compounds and nutrients. Supercritical fluid extraction was proposed as a method for a fast and selective extraction of hydrophobic compounds with a pharmaceutical potential from this matrix. Chromatographic analysis showed that the pomace contained significant amounts of such substances, the most abundant of them were ursolic acid, oleanolic acid, and β-sitosterol. The solubility was chosen as a primary factor for a selection of the extraction conditions; the best results were acquired for a temperature of 80 °C and a pressure of 30 MPa. The equation proposed by Chrastil was applied for the description of the impact of the process parameters on the solubility of the analytes; the obtained values of coefficients of determination were satisfactory, despite the fact that the equation was developed for binary systems. The extraction curves obtained during the experiments were used for the description of the process kinetics using the Broken plus Intact Cell model. The impact of the temperature, pressure, and flow rate of carbon dioxide on the mass transfer phenomena was investigated. The data obtained allowed the prediction of the extraction curve for the process conducted on the larger scale. Full article
(This article belongs to the Special Issue Green Extraction, Separation and Purification Processes)
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Open AccessArticle
Microwave-Assisted Extraction of Phenolic Compounds from Melastoma sanguineum Fruit: Optimization and Identification
Molecules 2018, 23(10), 2498; https://doi.org/10.3390/molecules23102498
Received: 5 September 2018 / Revised: 18 September 2018 / Accepted: 27 September 2018 / Published: 29 September 2018
Cited by 3 | PDF Full-text (1515 KB) | HTML Full-text | XML Full-text
Abstract
A microwave-assisted extraction (MAE) technology optimized by response surface methodology (RSM) was established to extract phenolic compounds from the fruit of Melastoma sanguineum. The effects of solvent composition, ratio of solvent to material, temperature, time and microwave power on phenol yield were [...] Read more.
A microwave-assisted extraction (MAE) technology optimized by response surface methodology (RSM) was established to extract phenolic compounds from the fruit of Melastoma sanguineum. The effects of solvent composition, ratio of solvent to material, temperature, time and microwave power on phenol yield were evaluated in single-factor tests. The three parameters exerting main impacts on phenol yield were further optimized by RSM. Under optimal extraction conditions (31.33% ethanol, solvent/material ratio of 32.21 mL/g, 52.24 °C, 45 min and 500 W), the total phenolic content was 39.02 ± 0.73 mg gallic acid equivalent (GAE)/g dry weight (DW). This MAE method performed better in comparison with two conventional methods, those being maceration (25.79 ± 1.03 mg GAE/g DW) and Soxhlet extraction (18.40 ± 1.34 mg GAE/g DW), using lower process temperature, shorter irradiation time, and lower organic solvent consumption. In addition, five flavonoids (epicatechin gallate, epicatechin, rutin, pigallocatechin and quercetin) and two phenolic acids (protocatechuic acid and chlorogenic acid) in the extract were identified and quantified using UPLC-MS/MS. Full article
(This article belongs to the Special Issue Green Extraction, Separation and Purification Processes)
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Open AccessArticle
Microwave (MW), Ultrasound (US) and Combined Synergic MW-US Strategies for Rapid Functionalization of Pharmaceutical Use Phenols
Molecules 2018, 23(9), 2360; https://doi.org/10.3390/molecules23092360
Received: 28 August 2018 / Revised: 10 September 2018 / Accepted: 13 September 2018 / Published: 15 September 2018
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Abstract
Increasingly stringent regulations aimed at protection of the natural environment have stimulated the search for new synthetic methodologies in organic and medicinal chemistry having no or minimum harmful effect. An interesting approach is the use of alternative activation factors, microwaves (MW) or ultrasounds [...] Read more.
Increasingly stringent regulations aimed at protection of the natural environment have stimulated the search for new synthetic methodologies in organic and medicinal chemistry having no or minimum harmful effect. An interesting approach is the use of alternative activation factors, microwaves (MW) or ultrasounds (US) and also their cross-combination, which has been tested in the fast and efficient creation of new structures. At present, an easy and green hybrid strategy (“Lego” chemistry) is generally recommended for the design of new substances from different chemistry building blocks. Often, selected biologically active components with specific chemical reactivities are integrated by a suitably designed homo- or heterodifunctional linker that modifies the functionality of the starting structure, allowing easy covalent linkage to another molecule. In this study, a fast introduction of heterodifunctional halogenoacidic linker to selected mono-, di- and triphenolic active substances, allowing their functionalization, was investigated. Nucleophilic substitution reaction was chosen to produce final ethers with the reactive carboxylic group from phenols. The functionalization was performed using various green factors initiating and supporting the chemical reactions (MW, US, MW-US). The benefits of the three green supporting methods and different conditions of reactions were analyzed and compared with the results of the reaction performed by conventional methods. Full article
(This article belongs to the Special Issue Green Extraction, Separation and Purification Processes)
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Open AccessArticle
Environmentally-Friendly Extraction of Flavonoids from Cyclocarya paliurus (Batal.) Iljinskaja Leaves with Deep Eutectic Solvents and Evaluation of Their Antioxidant Activities
Molecules 2018, 23(9), 2110; https://doi.org/10.3390/molecules23092110
Received: 26 July 2018 / Revised: 14 August 2018 / Accepted: 14 August 2018 / Published: 22 August 2018
Cited by 2 | PDF Full-text (1185 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Deep eutectic solvents (DESs) are commonly employed as environmentally-friendly solvents in numerous chemical applications owing to their unique physicochemical properties. In this study, a novel and environmentally-friendly extraction method based on ultrasound assisted-deep eutectic solvent extraction (UAE-DES) was investigated for the extraction of [...] Read more.
Deep eutectic solvents (DESs) are commonly employed as environmentally-friendly solvents in numerous chemical applications owing to their unique physicochemical properties. In this study, a novel and environmentally-friendly extraction method based on ultrasound assisted-deep eutectic solvent extraction (UAE-DES) was investigated for the extraction of flavonoids from Cyclocarya paliurus (Batal.) Iljinskaja (C. paliurus) leaves, and the antioxidant activities of these flavonoids were evaluated. Nine different DES systems based on either two or three components were tested, and the choline chloride/1,4–butanediol system (1:5 molar ratio) was selected as the optimal system for maximizing the flavonoid extraction yields. Other extraction conditions required to achieve the maximum flavonoid extraction yields from the leaves of C. paliurus were as follows: DES water content (v/v), 30%; extraction time, 30 min; temperature, 60 °C; and solid-liquid ratio, 20 mg/mL. Liquid chromatography-mass spectrometry allowed the detection of five flavonoids in the extract, namely kaempferol-7-O-α-l-rhamnoside, kaempferol, quercetin, quercetin-3-O-β-d-glucuronide, and kaempferol-3-O-β-d-glucuronide. In vitro antioxidant tests revealed that the flavonoid-containing extract exhibited strong DPPH and ABTS radical-scavenging abilities. Results indicate that UAE-DES is a suitable approach for the selective extraction of flavonoids from C. paliurus leaves, and DESs can be employed as sustainable extraction media for other bioactive compounds. Full article
(This article belongs to the Special Issue Green Extraction, Separation and Purification Processes)
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Open AccessArticle
Increasing Yield and Antioxidative Performance of Litchi Pericarp Procyanidins in Baked Food by Ultrasound-Assisted Extraction Coupled with Enzymatic Treatment
Molecules 2018, 23(9), 2089; https://doi.org/10.3390/molecules23092089
Received: 20 July 2018 / Revised: 12 August 2018 / Accepted: 14 August 2018 / Published: 21 August 2018
Cited by 2 | PDF Full-text (2864 KB) | HTML Full-text | XML Full-text
Abstract
Extraction with organic solvents is a traditional method to isolate bioactive compounds, which is energy-wasting and time-consuming. Therefore, enzyme and ultrasound treatments were combined to assist the extraction of oligomeric procyanidins from litchi pericarp (LPOPC), as an innovative approach to replace conventional extraction [...] Read more.
Extraction with organic solvents is a traditional method to isolate bioactive compounds, which is energy-wasting and time-consuming. Therefore, enzyme and ultrasound treatments were combined to assist the extraction of oligomeric procyanidins from litchi pericarp (LPOPC), as an innovative approach to replace conventional extraction methods. Under optimum conditions (enzyme concentration 0.12 mg/mL, ultrasonic power 300 W, ultrasonic time 80 min, and liquid/solid ratio 10 mL/g), the yield of LPOPC could be improved up to 13.5%. HPLC analysis indicated that the oligomeric procyanidins (OPC) content of LPOPC from proposed extraction was up to 89.6%, mainly including (−)-epicatechin, procyanidin A1, A2, and A-type procyanidin trimer. Moreover, LPOPC powder was added in baked food to inhibit the lipid peroxidation. It was found that 0.2% (w/w) of LPOPC could maintain the quality of cookies in the first 7 days, by decreasing the peroxide values. The procyanidin dimers and trimers in LPOPC played more important roles as antioxidants compared to monomers during storage. The results also showed that the combined extraction process can be considered as a useful and efficient method for the extraction of functional components from other plant sources. Full article
(This article belongs to the Special Issue Green Extraction, Separation and Purification Processes)
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Open AccessArticle
Preparation and Application of Standardized Typical Volatile Components Fraction from Turmeric (Curcuma longa L.) by Supercritical Fluid Extraction and Step Molecular Distillation
Molecules 2018, 23(7), 1831; https://doi.org/10.3390/molecules23071831
Received: 29 June 2018 / Revised: 18 July 2018 / Accepted: 19 July 2018 / Published: 23 July 2018
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Abstract
A green and reliable method using supercritical fluid extraction (SFE) and molecular distillation (MD) was optimized for the separation and purification of standardized typical volatile components fraction (STVCF) from turmeric to solve the shortage of reference compounds in quality control (QC) of volatile [...] Read more.
A green and reliable method using supercritical fluid extraction (SFE) and molecular distillation (MD) was optimized for the separation and purification of standardized typical volatile components fraction (STVCF) from turmeric to solve the shortage of reference compounds in quality control (QC) of volatile components. A high quality essential oil with 76.0% typical components of turmeric was extracted by SFE. A sequential distillation strategy was performed by MD. The total recovery and purity of prepared STVCF were 97.3% and 90.3%, respectively. Additionally, a strategy, i.e., STVCF-based qualification and quantitative evaluation of major bioactive analytes by multiple calibrated components, was proposed to easily and effectively control the quality of turmeric. Compared with the individual calibration curve method, the STVCF-based quantification method was demonstrated to be credible and was effectively adapted for solving the shortage of reference volatile compounds and improving the QC of typical volatile components in turmeric, especially its functional products. Full article
(This article belongs to the Special Issue Green Extraction, Separation and Purification Processes)
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Open AccessArticle
Influence of Extraction Conditions on Ultrasound-Assisted Recovery of Bioactive Phenolics from Blueberry Pomace and Their Antioxidant Activity
Molecules 2018, 23(7), 1685; https://doi.org/10.3390/molecules23071685
Received: 28 June 2018 / Revised: 8 July 2018 / Accepted: 9 July 2018 / Published: 11 July 2018
Cited by 5 | PDF Full-text (1427 KB) | HTML Full-text | XML Full-text
Abstract
The increase in diet-related chronic diseases has prompted the search for health-promoting compounds and methods to ensure their quality. Blueberry pomace is a rich yet underutilized source of bioactive polyphenols. For these high-value bioactive molecules, ultrasound-assisted extraction (USAE) is an attractive and green [...] Read more.
The increase in diet-related chronic diseases has prompted the search for health-promoting compounds and methods to ensure their quality. Blueberry pomace is a rich yet underutilized source of bioactive polyphenols. For these high-value bioactive molecules, ultrasound-assisted extraction (USAE) is an attractive and green alternative to conventional extraction techniques for improving purity and yields. This study aimed to assess the impact of USAE parameters (sonication time, solvent composition, solid/liquid ratio, pH and temperature) on the recovery of phenolic compounds from blueberry pomace and antioxidant activity of the extracts. Total phenolic, flavonoid and anthocyanin contents (TPC, TFC and TAC) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity were analysed. USAE in 50% ethanol/water was the most efficient, yielding the highest TPC (22.33 mg/g dry matter (DM)), TFC (19.41 mg/g DM), TAC (31.32 mg/g DM) and DPPH radical scavenging activity (41.79 mg Trolox/g DM). USAE in water showed the lowest values even at low (1/40) solid/liquid ratio (7.85 mg/g DM, 3.49 mg/g DM, and 18.96 mg/g DM for TPC, TFC and TAC, respectively). Decreasing the solid/liquid ratio in water or 50% ethanol significantly increased TPC, TFC, TAC and DPPH radical scavenging. With ethanol, increasing the temperature in the range 20–40 °C decreased TPC but increased TFC and DPPH radical scavenging activity. Anthocyanin profiles of water and ethanolic extracts were qualitatively similar, consisting of malvidin, delphinidin, petunidin and cyanidin. These findings indicate that USAE is a method of choice for extracting high-value bioactive phenolics from blueberry pomace. Selective enrichment of different phenolic fractions is possible under select extraction conditions. Full article
(This article belongs to the Special Issue Green Extraction, Separation and Purification Processes)
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Open AccessArticle
Using Natural Biomacromolecules for Adsorptive and Enzymatic Removal of Aniline Blue from Water
Molecules 2018, 23(7), 1606; https://doi.org/10.3390/molecules23071606
Received: 6 June 2018 / Revised: 24 June 2018 / Accepted: 25 June 2018 / Published: 2 July 2018
Cited by 2 | PDF Full-text (3301 KB) | HTML Full-text | XML Full-text
Abstract
The present study investigated the adsorptive and enzymatic removal of aniline blue dye (AB) from aqueous solution using waxy riceprocessing waste (RW), peanut shell (PS), microbial waste of Aspergillus niger (MW) as low cost adsorbents, and laccase (Lac) as a biocatalyst. Commercial activated [...] Read more.
The present study investigated the adsorptive and enzymatic removal of aniline blue dye (AB) from aqueous solution using waxy riceprocessing waste (RW), peanut shell (PS), microbial waste of Aspergillus niger (MW) as low cost adsorbents, and laccase (Lac) as a biocatalyst. Commercial activated carbon (AC) was also employed to compare the adsorption performance with the three adsorbents. Dye removal was examined under various parameters in batch experiments. It was found that dye removal by RW and Lac was 89–94% noticeably better than that by MW and PS (20–70%). In any cases, AC produced the highest dye removal among the tested materials. The kinetics, isotherms, and thermodynamics were then analyzed to elucidate the adsorption process by the four adsorbents. The pseudo-second order kinetic was superior to the pseudo first order kinetic model in describing adsorption for all adsorbents. The Langmuir model fitted the adsorption process very well, indicating monolayer coverage of dyes on a solid surface. A thermodynamic analysis of enthalpy (ΔH°), entropy (ΔS°), and Gibbs free energy (ΔG°) classified the adsorption as a nonspontaneous and endothermic process. The results reveal diverse natural materials (e.g., processing waste RW) as novel substitutes for traditional activated carbon, as well as laccase as a green catalyst for the treatment of dye wastewater. Full article
(This article belongs to the Special Issue Green Extraction, Separation and Purification Processes)
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Open AccessArticle
Process Optimization, Characterization and Antioxidant Capacity of Oat (Avena Sativa L.) Bran Oil Extracted by Subcritical Butane Extraction
Molecules 2018, 23(7), 1546; https://doi.org/10.3390/molecules23071546
Received: 21 May 2018 / Revised: 13 June 2018 / Accepted: 13 June 2018 / Published: 27 June 2018
Cited by 1 | PDF Full-text (1891 KB) | HTML Full-text | XML Full-text
Abstract
Oat bran is a traditional agricultural byproduct and rarely used in edible oil processing. In this paper, oat bran oil (OBO) was firstly extracted by subcritical butane extraction (SBE) and the extraction process was optimized using response surface methodology. Three variables involving liquid-to-solid [...] Read more.
Oat bran is a traditional agricultural byproduct and rarely used in edible oil processing. In this paper, oat bran oil (OBO) was firstly extracted by subcritical butane extraction (SBE) and the extraction process was optimized using response surface methodology. Three variables involving liquid-to-solid ratio, extraction time and extraction temperature were studied. The optimum conditions for extraction of OBO were obtained as follows: liquid-to-solid ratio 4.30, extraction time 48.15 min, and extraction temperature 46.52 °C. Based on this, an alternative method (SBE-e) for cosolvent (ethanol) was proposed to improve SBE method. Compared to conventional hexane extraction (CHE), the SBE-e had significant effect on yield, bioactive compounds (phytosterols and phenols) and antioxidant capacity (AC) in the extracted OBO. The results indicated that the proposed methods were appropriate for OBO extraction. Additionally, OBO had the potential to be an acceptable substitute for edible oil, owing to its desirable physicochemical characteristics, a balanced fatty acids composition and high antioxidant capacity. Full article
(This article belongs to the Special Issue Green Extraction, Separation and Purification Processes)
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