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Green Extraction of Natural Products
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Green Extraction of Natural Products

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

Deadline for manuscript submissions: closed (1 December 2019) | Viewed by 80427

Special Issue Editors

Dr. Maria Lisa Clodoveo

E-Mail Website
Guest Editor
Interdisciplinary Department of Medicine, University of Bari, Bari, Italy
Interests: emerging food technologies; food process scale-up; functional foods; food by-product; sustainability; circular economy; unitary operations of the gastronomic sciences
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Filomena Corbo

E-Mail Website
Guest Editor
Department of Pharmacy-Pharmaceutical Sciences, Università degli studi Aldo Moro, Bari, Italy
Interests: natural product chemistry
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Green and sustainable extraction methods of natural products is currently a hot research topic in the multidisciplinary area of applied chemistry, biology and technology.

Therefore, we believe that a Special Issue in the journal Molecules focused on new and innovative technologies, process intensification, agro-solvents and energy saving will be strategic to give an overview of the current status and future perspectives.

Considering your significant research background in the following fields:

► Alternative solvents for green extraction

•  Supercritical fluid extraction •  Subcritical water extraction • Agrosolvents  • Solvent free extraction • Green solvents: ionic liquids, micellar extraction, etc.

► Sustainable and clean extraction technologies • Ultrasound and microwave processes • High pressure assisted processes • Pulse Electric field processes • Extrusion • Enzymatic extraction

► Innovative extraction process design

• Experimental design • Optimal design • Intensification (mini, micro devices) • Reaction/separation coupling (Membrane reactors, Adsorptive reactors, Reactive distillation, Reactive extraction) • Cleaner production

► Valorization of by products and biorefinery

• Thermal processes • Innovative technologies • Product optimization, characterization, stabilization and applications • Industrial applications for the production of fuels, fine chemicals, flavoring agents and pharmaceuticals

► Industrial and case study applications

• Pharmaceutic • Food and nutrition • Cosmetic and perfume • Fuel and bio-energy enzymatic extraction • Fiscal and economic benefits of sustainable green processes 

► New tools for green extraction education and operator training 

We strongly believe that the main strength of this topic is the high value coming from the encounter between research and industry, in particular the research activities focused on the scale-up process, from the lab experiment to the full scale plant, moving up through technological readiness levels, so, from the invention to the market.

We cordially invite you to contribute the original research papers or reviews to this Special Issue of Molecules. 

Prof. Maria Lisa Clodoveo
Prof. Filomena Corbo
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Molecules is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Green extraction
  • Separation and purification
  • Intensification
  • Enabling technologies
  • Deep eutectic solvents
  • Natural products
  • Supercritical fluids

Published Papers (16 papers)

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17 pages, 4132 KiB  
Article
Optimization of Ultrasound-Assisted Extraction Condition for Phenolic Compounds, Antioxidant Activity, and Epigallocatechin Gallate in Lipid-Extracted Microalgae
by Da Hye Gam, Song Yi Kim and Jin Woo Kim
Molecules 2020, 25(3), 454; https://doi.org/10.3390/molecules25030454 - 21 Jan 2020
Cited by 24 | Viewed by 4140
Abstract
Lipid-extracted microalgae (LEM, Tetraselmis KCTC 12236BP), a solid waste by-product obtained from algal biodiesel production, is typically considered a rich source of antioxidant compounds, including phenolic compounds. The purpose of this study was to apply a statistically-based methodology to enhance the extraction of [...] Read more.
Lipid-extracted microalgae (LEM, Tetraselmis KCTC 12236BP), a solid waste by-product obtained from algal biodiesel production, is typically considered a rich source of antioxidant compounds, including phenolic compounds. The purpose of this study was to apply a statistically-based methodology to enhance the extraction of total phenolic compounds (TPCs) and antioxidant activity (AA) from LEM and to verify the production of epigallocatechin gallate (EGCG), a bioactive material, under optimum conditions. The optimal extractions of TPC and AA were explored by varying the key variables, including the extraction temperature, ethanol concentration, extraction time, and ultrasonic power, through statistical optimization. The optimal extraction conditions were identified through 27 runs following the central composite design. The regression analyses of TPC and AA showed good fit of the experimental data to the second-order polynomial models, with coefficient of determination (R2) values of 0.8769 and 0.8432, respectively. In the variation experiment, the maximum TPC and AA values of 9.8 mg GAE/g and 91.8% were obtained respectively with an extraction temperature of 74.4 °C, ethanol concentration of 55.4%, extraction time of 59.6 min, and ultrasonic power of 700 W. HPLC coupled with diode array detection was used to identify and quantify the phenolic compounds in the extracts, and EGCG (0.12 mg/g DM) was identified as a major peak in the analysis, demonstrating that high value-added material with a bioactive property can be produced from LEM. The results indicated that statistical optimization is applicable for optimizing the extraction of TPC and AA from LEM and provided a scientific basis for applying ultrasound-assisted extraction on an industrial scale by optimizing the conditions. LEM has a high TPC value, particularly with regard to EGCG, and excellent AA, considering it is highly used as a functional material for food, cosmetics, and medicine. Full article
(This article belongs to the Special Issue Green Extraction of Natural Products)
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15 pages, 879 KiB  
Article
Understanding Olive Oil Stability Using Filtration and High Hydrostatic Pressure
by Lorenzo Guerrini, Bruno Zanoni, Carlotta Breschi, Giulia Angeloni, Piernicola Masella, Luca Calamai and Alessandro Parenti
Molecules 2020, 25(2), 420; https://doi.org/10.3390/molecules25020420 - 20 Jan 2020
Cited by 23 | Viewed by 3515
Abstract
Veiled extra virgin olive oil (VEVOO) is very attractive on the global market. A study was performed to highlight the role of different amounts of water and microorganisms on the evolution of VEVOO quality during storage, using the selective effects of the application [...] Read more.
Veiled extra virgin olive oil (VEVOO) is very attractive on the global market. A study was performed to highlight the role of different amounts of water and microorganisms on the evolution of VEVOO quality during storage, using the selective effects of the application of individual or combined filtration and high hydrostatic pressure (HHP) treatments. Four oil processing trials were carried out in four replicates, resulting in a full factorial design with two independent fixed factors: filtration and HPP treatments. The turbidity of all the olive oil samples was characterized. Furthermore, all the olive oil samples were analysed for legal parameters, volatile organic compounds and phenolic compounds during the storage tests. The microbial contamination in the presence of a high level of water activity (>0.6 Aw) was related to the formation of volatile aroma compounds, which were responsible for the “fusty” sensory defect. Furthermore, high water activity values were related to an increase in the hydrolytic degradation rate of the phenolic compounds. The oil turbidity has to be planned and controlled, starting from adjustment of the water content and application of good manufacturing practices. Full article
(This article belongs to the Special Issue Green Extraction of Natural Products)
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11 pages, 885 KiB  
Article
Optimization of Microwave-Assisted Extraction of Antioxidants from Bamboo Shoots of Phyllostachys pubescens
by Gualtiero Milani, Francesca Curci, Maria Maddalena Cavalluzzi, Pasquale Crupi, Isabella Pisano, Giovanni Lentini, Maria Lisa Clodoveo, Carlo Franchini and Filomena Corbo
Molecules 2020, 25(1), 215; https://doi.org/10.3390/molecules25010215 - 05 Jan 2020
Cited by 24 | Viewed by 4238
Abstract
Bamboo is a well-known medicinal plant in Southeast Asia that recently has attracted attention for its high polyphenol content and its medical and nutraceutical applications. In this work, polyphenols have been recovered for the first time by microwave-assisted extraction (MAE) from an unusual [...] Read more.
Bamboo is a well-known medicinal plant in Southeast Asia that recently has attracted attention for its high polyphenol content and its medical and nutraceutical applications. In this work, polyphenols have been recovered for the first time by microwave-assisted extraction (MAE) from an unusual Italian cultivar of Phyllostachys pubescens bamboo shoots. The effects of three independent variables, such as extraction time, temperature, and solid/liquid ratio, on polyphenol recovery yield were investigated and successfully optimized through the response surface methodology. We demonstrated that MAE is an excellent polyphenols extraction technique from bamboo shoots because the total phenolic content obtained under microwave irradiation optimal conditions (4 min at 105 °C with 6.25 mg/mL ratio) was about eight-fold higher than that obtained with the conventional extraction method. Furthermore, higher total flavonoid content was also obtained under MAE. Consistent with these results, MAE enhanced the extract antioxidant properties with significant improved DPPH, ABTS, and FRAP scavenging ability. Therefore, this innovative extraction process enhances the recovery of biologically active compounds from Phyllostachys pubescens bamboo shoots with a dramatic reduction of time and energy consumption, which paves the way for its industrial application in functional food production. Full article
(This article belongs to the Special Issue Green Extraction of Natural Products)
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14 pages, 1557 KiB  
Article
Optimization of Ultrasound Assisted Extraction (UAE) of Kinsenoside Compound from Anoectochilus roxburghii (Wall.) Lindl by Response Surface Methodology (RSM)
by Biyun Yang, Mengyuan Zhang, Haiyong Weng, Yong Xu and Lihui Zeng
Molecules 2020, 25(1), 193; https://doi.org/10.3390/molecules25010193 - 02 Jan 2020
Cited by 22 | Viewed by 3518
Abstract
The purpose of this study was to establish an extraction method for the kinsenoside compound from the whole plant Anoectochilus roxburghii. Ultrasound assisted extraction (UAE) and Ultra-high performance liquid chromatography (UPLC) method were used to extract and determine the content of kinsenoside, [...] Read more.
The purpose of this study was to establish an extraction method for the kinsenoside compound from the whole plant Anoectochilus roxburghii. Ultrasound assisted extraction (UAE) and Ultra-high performance liquid chromatography (UPLC) method were used to extract and determine the content of kinsenoside, while response surface method (RSM) was used to optimize the extraction process. The best possible range for methanol concentration (0–100%), the liquid-solid ratio (5:1–30:1 mL/g), ultrasonic power (240–540 W), duration of ultrasound (10–50 min), ultrasonic temperature (10–60 °C), and the number of extractions (1–4) were obtained according to the single factor experiments. Then, using the Box-Behnken design (BBD) of response surface analysis, the optimum extraction conditions were obtained with 16.33% methanol concentration, the liquid-solid ratio of 10.83:1 mL/g and 35.00 °C ultrasonic temperature. Under these conditions, kinsenoside extraction yield reached 32.24% dry weight. The best conditions were applied to determine the kinsenoside content in seven different cultivation ages in Anoectochilus roxburghii. Full article
(This article belongs to the Special Issue Green Extraction of Natural Products)
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15 pages, 3870 KiB  
Article
Simultaneous Optimization of Ultrasound-Assisted Extraction for Flavonoids and Antioxidant Activity of Angelica keiskei Using Response Surface Methodology (RSM)
by Lei Zhang, Yuhuan Jiang, Xuening Pang, Puyue Hua, Xiang Gao, Qun Li and Zichao Li
Molecules 2019, 24(19), 3461; https://doi.org/10.3390/molecules24193461 - 24 Sep 2019
Cited by 43 | Viewed by 4030
Abstract
Angelica keiskei Koidzumi (A. keiskei), as a Japanese edible herbal plant, enjoys a variety of biological activities due to the presence of numerous active compounds, especially flavonoids. This study aims for the optimization of ultrasound-assisted extraction (UAE) for flavonoids in A. [...] Read more.
Angelica keiskei Koidzumi (A. keiskei), as a Japanese edible herbal plant, enjoys a variety of biological activities due to the presence of numerous active compounds, especially flavonoids. This study aims for the optimization of ultrasound-assisted extraction (UAE) for flavonoids in A. keiskei and their antioxidant activity by using the response surface methodology (RSM). Single-factor experiments and a four-factor three-level Box–Behnken design (BBD) were performed to explore the effects of the following parameters on flavonoid extraction and antioxidant activity evaluation: ultrasonic temperature (X1), ultrasonic time (X2), ethanol concentration (X3) and liquid–solid ratio (X4). The optimum conditions of the combination of total flavonoid content (TFC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity (DPPH-RSC) and ferric-reducing antioxidant power (FRAP) were as follows: X1 = 80 °C, X2 = 4 min, X3 = 78%, X4 = 35 mL/g, respectively. The experimental results provide a theoretical basis for the extensive utilization of A. keiskei and flavonoids extraction from A. keiskei as a potential source of antioxidants. Full article
(This article belongs to the Special Issue Green Extraction of Natural Products)
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17 pages, 1344 KiB  
Article
Quickly Identifying High-Risk Variables of Ultrasonic Extraction Oil from Multi-Dimensional Risk Variable Patterns and a Comparative Evaluation of Different Extraction Methods on the Quality of Forsythia suspensa Seed Oil
by Liangshan Ming, Hao Huang, Yumao Jiang, Gengjinsheng Cheng, Daoying Zhang and Zhe Li
Molecules 2019, 24(19), 3445; https://doi.org/10.3390/molecules24193445 - 23 Sep 2019
Cited by 10 | Viewed by 2840
Abstract
Generally, essential oils and components of interest are extracted from plants using organic solvent, distillation, ultrasound and supercritical extraction methods. Ultrasonic extraction (UE) has the advantage of high efficiency, but its process is complicated and it has numerous variables. In this study, an [...] Read more.
Generally, essential oils and components of interest are extracted from plants using organic solvent, distillation, ultrasound and supercritical extraction methods. Ultrasonic extraction (UE) has the advantage of high efficiency, but its process is complicated and it has numerous variables. In this study, an L18-Hunter experimental design was applied for the first time to investigate the practicability of applying UE to Forsythia suspensa seed oil. Six potential high-risk variables, including numerical and non-numeric types, were obtained from the risk analysis and their impacts on global yield and antioxidant activity were screened. Furthermore, oils obtained by different extraction processes (i.e., UE, supercritical fluid extraction (SFE), soxhlet extraction (SE) and hydrodistillation extraction (HD)) were analyzed. A comparative study of these oils was characterized and compared by FT-IR, GC-MS and antioxidant activity. The obtained results show that the type of solvent, solvent-to-solid ratio, extraction power and time were the significant variables affecting the extraction yield, whereas antioxidant activity was only affected by the type of solvent. The regression coefficients of the yield and antioxidant activity models were 0.79 and 0.91, and the ANOVA of the models were 0.013 and <0.0001, respectively. Beta-Pinene was the main abundant component in the oils for the UE, SFE, SE and HD methods and the content was about 46%~52.4%. In conclusion, the L18-Hunter design could be used as an effective experimental design method for rapid screening of high-risk variables. Regarding extraction efficiency, chemical composition and biological activity, UE not only offered a robust Forsythia suspensa seed oil extraction process, but also provided a time- and cost-effective advantage to the food and pharmaceutical industry when compared to the SFE, SE and HD extraction processes. Full article
(This article belongs to the Special Issue Green Extraction of Natural Products)
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13 pages, 2450 KiB  
Article
Green Approach Extraction of Perezone from the Roots of Acourtia platyphilla (A. Grey): A Comparison of Four Activating Modes and Supercritical Carbon Dioxide
by René Escobedo-González, Andrea Vázquez Vázquez Cabañas, Armando Martínez González, Pablo Mendoza Sánchez, Zenaida Saavedra-Leos, Julián Cruz-Olivares, Juan Nava Serrano, Joel Martínez and René Miranda Ruvalcaba
Molecules 2019, 24(17), 3035; https://doi.org/10.3390/molecules24173035 - 21 Aug 2019
Cited by 8 | Viewed by 2866
Abstract
Perezone, a sesquiterpene quinone, is a very important molecule due to its pharmacological activities in addition to the fact that it is considered to be the first secondary metabolite isolated in the new world (America–Mexico, 1852). This study aims to offer a green [...] Read more.
Perezone, a sesquiterpene quinone, is a very important molecule due to its pharmacological activities in addition to the fact that it is considered to be the first secondary metabolite isolated in the new world (America–Mexico, 1852). This study aims to offer a green comparative study about the extraction of the target molecule from the roots of the vegetable specimen Acourtia platyphilla (A. Grey). The study was performed comparing five different modes of extraction: supercritical CO2, electromagnetic infrared and microwave irradiations, mechanical-wave ultrasound versus typical mantle heating procedure. An exhaustive comparative-discussion of the obtained results is provided. It is worth noting that the corresponding quantifications were established using 1H NMR, correlating appropriately the integrals of the vinylic proton H-6 of perezone with the aromatic singlet of p-dinitrobenzene employed as an internal reference. It is also important to highlight that the four presented procedures are novel modes to extract perezone. Finally, a complementary study about the solubility of the target sesquiterpene quinone related to the use of supercritical CO2 is also reported. Full article
(This article belongs to the Special Issue Green Extraction of Natural Products)
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14 pages, 600 KiB  
Article
Technology and Process Design for Phenols Recovery from Industrial Chicory (Chicorium intybus) Leftovers
by Camilla Maria Cova, Luisa Boffa, Marco Pistocchi, Silver Giorgini, Rafael Luque and Giancarlo Cravotto
Molecules 2019, 24(15), 2681; https://doi.org/10.3390/molecules24152681 - 24 Jul 2019
Cited by 15 | Viewed by 3044
Abstract
Vegetal leftovers from the agro–food industry represent a huge source of primary and secondary metabolites, vitamin, mineral salts and soluble as well as insoluble fibers. Economic reports on the growth in the polyphenol market have driven us to focus our investigation on chicory [...] Read more.
Vegetal leftovers from the agro–food industry represent a huge source of primary and secondary metabolites, vitamin, mineral salts and soluble as well as insoluble fibers. Economic reports on the growth in the polyphenol market have driven us to focus our investigation on chicory (Chicorium intybus L.), which is one of the most popular horticultural plants in the world and a rich source of phenolic compounds. Ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE) and their simultaneous combination, using either ethanol/water or water alone (also sub-critical), have been investigated with the aim of designing a green and efficient extraction process. Higher total-polyphenol yields as well as dramatic reductions in extraction times and solvent consumption have been obtained under these conditions. ANOVA test for analyses of variance followed by the Tukey honestly significant difference (HSD) post-hoc test of multiple comparisons was used in the statistical analysis. MAE experiments performed with sub-critical water, and MW/US experiments with an ethanol solution have shown polyphenol recovery values of up to ~3 g of gallic acid equivalents (GAE) per kg of fresh material in only 15 min, while conventional extraction required 240 min to obtain the same result. Full article
(This article belongs to the Special Issue Green Extraction of Natural Products)
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16 pages, 2241 KiB  
Article
Flavonoids from Morus alba L. Leaves: Optimization of Extraction by Response Surface Methodology and Comprehensive Evaluation of Their Antioxidant, Antimicrobial, and Inhibition of α-Amylase Activities through Analytical Hierarchy Process
by Hao Cui, Tenghui Lu, Mingxin Wang, Xintong Zou, Yang Zhang, Xiudong Yang, Yao Dong and Hongli Zhou
Molecules 2019, 24(13), 2398; https://doi.org/10.3390/molecules24132398 - 28 Jun 2019
Cited by 40 | Viewed by 4385
Abstract
To explore the flavonoids from Morus alba L. leaves (MLF), the process of extracting was optimized by a response surface methodology and the antimicrobial and antioxidant activities were evaluated in vitro. The yield of flavonoids reached 50.52 mg g−1 under the optimized [...] Read more.
To explore the flavonoids from Morus alba L. leaves (MLF), the process of extracting was optimized by a response surface methodology and the antimicrobial and antioxidant activities were evaluated in vitro. The yield of flavonoids reached 50.52 mg g−1 under the optimized extraction conditions (i.e., extraction temperature, 70.85 °C; solvent concentration, 39.30%; extraction time, 120.18 min; and liquid/solid ratio, 34.60:1). The total flavonoids were extracted in organic solvents with various polarities, including petroleum ether (MLFp), ethyl acetate (MLFe), and n-butanol (MLFb). In vitro, the four MLF samples exhibited good antioxidant activities for scavenging of 2, 2′-azinobis-(3-ethylbenz-thiazoline-6-sulphonate) radical, 1, 1-diphenyl-2-picrylhydrazyl radical, and total reducing power. Regarding antimicrobial efficacy, the MLF samples suppressed the development of Staphylococcus aureus, Bacillus subtilis, and Bacillus pumilus. The MLF samples inhibited α-amylase activity to a certain extent. The analytical hierarchy process (AHP) was used to evaluate comprehensively the bioactivities of the MLF samples. The AHP results revealed that the bioactivity comprehensive score (78.83 μg mL−1) of MLFe was optimal among the four MLF samples. Morus alba L. leaves also exhibited non-hemolytic properties. All bioactivities suggested the potential of MLFe as a candidate resource in the food and drug industries. Full article
(This article belongs to the Special Issue Green Extraction of Natural Products)
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18 pages, 3815 KiB  
Article
Rapid and Efficient Separation of Decursin and Decursinol Angelate from Angelica gigas Nakai using Ionic Liquid, (BMIm)BF4, Combined with Crystallization
by Alice Nguvoko Kiyonga, Ji-Hun An, Ki Yong Lee, Changjin Lim, Young-Ger Suh, Young-Won Chin and Kiwon Jung
Molecules 2019, 24(13), 2390; https://doi.org/10.3390/molecules24132390 - 28 Jun 2019
Cited by 4 | Viewed by 3748
Abstract
Ionic liquids (ILs) have gained much attention as alternative solvents to volatile organic solvents due to their attractive properties. This study aimed to develop an efficient method for the selective separation of decursin (D) and decursinol angelate (DA) from Angelica gigas Nakai ( [...] Read more.
Ionic liquids (ILs) have gained much attention as alternative solvents to volatile organic solvents due to their attractive properties. This study aimed to develop an efficient method for the selective separation of decursin (D) and decursinol angelate (DA) from Angelica gigas Nakai (A. gigas) using ILs and crystallization. The IL 1-butyl-3-methylimidazolium tetrafluoroborate ((BMIm)BF4) was the most efficient at extracting D and DA. Parameters including solid-to-liquid ratio, time, and temperature were optimized by response surface methodology (RSM). Under optimal extraction conditions (1 g/6.5 mL solid-to-liquid ratio, 60 °C temperature, and 120 min time), the extraction yields of D and DA were 43.32 mg/g (97.06%) and 17.87 mg/g (97.12%), respectively. Moreover, drowning out crystallization using deionized water (DW) as an anti-solvent offered an excellent ability to recover D and DA from the A. gigas–(BMIm)BF4 extraction solution. The rates of recovery and the total purity of D and DA were found to be greater than 97%. Therefore, a rapid and efficient method of combining ILs with crystallization was effectively achieved for the selective separation of D and DA. This approach is assumed to be beneficial in the pharmaceutical industry for the effective obtention of D- and DA-enriched products. Full article
(This article belongs to the Special Issue Green Extraction of Natural Products)
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13 pages, 1248 KiB  
Article
Implementation of the Sono-Heat-Exchanger in the Extra Virgin Olive Oil Extraction Process: End-User Validation and Analytical Evaluation
by Lorenzo Cecchi, Maria Bellumori, Filomena Corbo, Gualtiero Milani, Maria Lisa Clodoveo and Nadia Mulinacci
Molecules 2019, 24(13), 2379; https://doi.org/10.3390/molecules24132379 - 27 Jun 2019
Cited by 10 | Viewed by 3330
Abstract
The use of innovative systems, such as the heat exchanger, for production of extra virgin olive oil should allow maintenance of the same quality of those oils derived from traditional processes, and presents specific advantages. The performance of this system was evaluated by [...] Read more.
The use of innovative systems, such as the heat exchanger, for production of extra virgin olive oil should allow maintenance of the same quality of those oils derived from traditional processes, and presents specific advantages. The performance of this system was evaluated by (i) determining the parameters directly measurable by the olive millers (i.e., end-user validation based on the production yields when the plant is located in different processing lines) and (ii) assessing the product quality through estimation of the content of phenolic and volatile compounds. The phenols were determined by High Performance Liquid Chromatography with Diode Array Detector (HPLC–DAD) before and after acidic hydrolysis while the volatile fraction was studied by Head-Space Solid-Phase-Micro-Extraction Gas-Chromatography with Mass Detector (HS–SPME–GC–MS). The use of the sono-heat-exchanger presents several advantages: it is a flexible machine, able to interface with all devices of the world’s leading manufacturers of the Extra Virgin Olive Oil (EVOO) extraction plant, and it guarantees shorter processing times and energy savings. Our results also pointed out its capability to increase the oil yields up to 5.5%, particularly when it extracts oil from unripe fruits, which in traditional processes yield oils with higher phenolic contents, but with lower oil yields. Overall, the quality of virgin olive oils was maintained, avoiding decreases of phenolic content or detrimental effects on the sensory characteristics. Full article
(This article belongs to the Special Issue Green Extraction of Natural Products)
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15 pages, 3358 KiB  
Article
Comparison of Artificial Neural Networks and Response Surface Methodology towards an Efficient Ultrasound-Assisted Extraction of Chlorogenic Acid from Lonicera japonica
by Hui-Chuan Yu, Shang-Ming Huang, Wei-Min Lin, Chia-Hung Kuo and Chwen-Jen Shieh
Molecules 2019, 24(12), 2304; https://doi.org/10.3390/molecules24122304 - 21 Jun 2019
Cited by 26 | Viewed by 3235
Abstract
Chlorogenic acid (CGA), a bioactive compound commonly found in plants, has been demonstrated possessing nutraceutical potential in recent years. However, the more critical issue concerning how to improve production efficacy of CGA is still limited. It is a challenge to harvest a large [...] Read more.
Chlorogenic acid (CGA), a bioactive compound commonly found in plants, has been demonstrated possessing nutraceutical potential in recent years. However, the more critical issue concerning how to improve production efficacy of CGA is still limited. It is a challenge to harvest a large amount of CGA without prolonging extraction time. In this study, the feasibility of using ultrasound for CGA extraction from Lonicera japonica was investigated. A central composite design (CCD) was employed to evaluate the effects of the operation parameters, including temperature, ethanol concentration, liquid to solid ratio, and ultrasound power on CGA yields. Meanwhile, the process of ultrasound-assisted extraction was optimized through modeling response surface methodology (RSM) and artificial neural network (ANN). The data indicated that CGA was efficiently extracted from the flower of Lonicera japonica by ultrasound assistance. The optimal conditions for the maximum extraction of CGA were as follows: The temperature at 33.56 °C, ethanol concentration at 65.88%, L/S ratio at 46:1 mL/g and ultrasound power at 150 W. ANN possessed greater optimization capacity than RSM for fitting experimental data and predicting the extraction process to obtain a maximum CGA yield. In conclusion, the process of ultrasound-assisted extraction can be well established by a methodological approach using either RSM or ANN, but it is worth mentioning that the ANN model used here showed the superiority over RSM for predicting and optimizing. Full article
(This article belongs to the Special Issue Green Extraction of Natural Products)
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16 pages, 1286 KiB  
Article
The EFSA Health Claim on Olive Oil Polyphenols: Acid Hydrolysis Validation and Total Hydroxytyrosol and Tyrosol Determination in Italian Virgin Olive Oils
by Maria Bellumori, Lorenzo Cecchi, Marzia Innocenti, Maria Lisa Clodoveo, Filomena Corbo and Nadia Mulinacci
Molecules 2019, 24(11), 2179; https://doi.org/10.3390/molecules24112179 - 10 Jun 2019
Cited by 72 | Viewed by 6354
Abstract
The health claims of olive oil represent an important marketing lever in raising the willingness to pay for a product, but world producers of extra virgin olive oil (EVOO) do not take advantage of it because there are still obstacles to their use. [...] Read more.
The health claims of olive oil represent an important marketing lever in raising the willingness to pay for a product, but world producers of extra virgin olive oil (EVOO) do not take advantage of it because there are still obstacles to their use. Among these, one issue is the lack of an official method for determination of all free and linked forms derived from secoiridoidic structures of hydroxytyrosol and tyrosol. In this study, different acidic hydrolytic procedures for analyzing the linked forms were tested. The best method was validated and then applied to more than 100 EVOOs. The content of oleuropein and ligstroside derivatives in EVOOs was indirectly evaluated comparing the amount of phenols before and after hydrolysis. After acidic hydrolysis, a high content of total tyrosol was found in most of the EVOOs. The use of a suitable corrective factor for the evaluation of hydroxytyrosol allows an accurate determination only using pure tyrosol as a standard. Further knowledge on the concentration of total hydroxytyrosol will assist in forecasting the resistance of oils against aging, its antioxidant potential and to better control its quality over time. Full article
(This article belongs to the Special Issue Green Extraction of Natural Products)
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23 pages, 7349 KiB  
Article
Alternate Ultrasound/Microwave Digestion for Deep Eutectic Hydro-distillation Extraction of Essential Oil and Polysaccharide from Schisandra chinensis (Turcz.) Baill
by Jun-Han Li, Wei Li, Sha Luo, Chun-Hui Ma and Shou-Xin Liu
Molecules 2019, 24(7), 1288; https://doi.org/10.3390/molecules24071288 - 02 Apr 2019
Cited by 24 | Viewed by 3834
Abstract
An alternating synergetic ultrasound/microwave method was applied to the simultaneous extraction of essential oils and polysaccharides with deep eutectic solvent (DES) from Schisandra chinensis. Under the optimal conditions, extract in the selected choline chloride-ethylene glycol 1:3 solvent yielded 12.2 mL/kg and 8.56 [...] Read more.
An alternating synergetic ultrasound/microwave method was applied to the simultaneous extraction of essential oils and polysaccharides with deep eutectic solvent (DES) from Schisandra chinensis. Under the optimal conditions, extract in the selected choline chloride-ethylene glycol 1:3 solvent yielded 12.2 mL/kg and 8.56 g/100g of essential oils and polysaccharides, respectively. The free radical scavenging and immunological activities of the polysaccharides and the antioxidant activity of the essential oils have also been investigated. The lymphocyte proliferation capacity was substantially improved by adding concanavalin A or lipopolysaccharides to polysaccharides (0.20 mg/mL). The IC50 values of the essential oils for scavenging DPPH obtained by hydro-distillation and DES ultrasound/microwave-assisted hydro-distillation (DES UMHD) were 52.34 µg/mL and 29.82 µg/mL, respectively. The essential oil obtained by DES UMHD had the highest reducing power (856.05 (TE)/g) at 150 g/mL and had the strongest inhibitory capacity (SC% = 18.12%). S. chinensis has the potential to be developed as a natural antioxidant. Full article
(This article belongs to the Special Issue Green Extraction of Natural Products)
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Review

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27 pages, 3495 KiB  
Review
Review of Alternative Solvents for Green Extraction of Food and Natural Products: Panorama, Principles, Applications and Prospects
by Farid Chemat, Maryline Abert Vian, Harish Karthikeyan Ravi, Boutheina Khadhraoui, Soukaina Hilali, Sandrine Perino and Anne-Sylvie Fabiano Tixier
Molecules 2019, 24(16), 3007; https://doi.org/10.3390/molecules24163007 - 19 Aug 2019
Cited by 290 | Viewed by 21732
Abstract
In recent years, almost all extraction processes in the perfume, cosmetic, pharmaceutical, food ingredients, nutraceuticals, biofuel and fine chemical industries rely massively on solvents, the majority of which have petroleum origins. The intricate processing steps involved in the industrial extraction cycle makes it [...] Read more.
In recent years, almost all extraction processes in the perfume, cosmetic, pharmaceutical, food ingredients, nutraceuticals, biofuel and fine chemical industries rely massively on solvents, the majority of which have petroleum origins. The intricate processing steps involved in the industrial extraction cycle makes it increasingly difficult to predict the overall environmental impact; despite the tremendous energy consumption and the substantial usage of solvents, often the yields are indicated in decimals. The ideal alternative solvents suitable for green extraction should have high solvency, high flash points with low toxicity and low environmental impacts, be easily biodegradable, obtained from renewable (non-petrochemical) resources at a reasonable price and should be easy to recycle without any deleterious effect to the environment. Finding the perfect solvent that meets all the aforementioned requirements is a challenging task, thus the decision for the optimum solvent will always be a compromise depending on the process, the plant and the target molecules. The objective of this comprehensive review is to furnish a vivid picture of current knowledge on alternative, green solvents used in laboratories and industries alike for the extraction of natural products focusing on original methods, innovation, protocols, and development of safe products. Full article
(This article belongs to the Special Issue Green Extraction of Natural Products)
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Other

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20 pages, 3645 KiB  
Perspective
Process Engineering Accelerating an Economic Industrialization Towards a Bio-Based World
by Lukas Uhlenbrock, Reinhard Ditz and Jochen Strube
Molecules 2019, 24(10), 1853; https://doi.org/10.3390/molecules24101853 - 14 May 2019
Cited by 6 | Viewed by 4662
Abstract
The transition towards a bio-based world is a challenging undertaking. This perspective paper, from an engineering point of view, aims to provide an overview of existing projects and academic disciplines highlighting the potential benefit of increased interdisciplinary exchanges. Furthermore, the current utilization of [...] Read more.
The transition towards a bio-based world is a challenging undertaking. This perspective paper, from an engineering point of view, aims to provide an overview of existing projects and academic disciplines highlighting the potential benefit of increased interdisciplinary exchanges. Furthermore, the current utilization of biomass to produce biogas is discussed, including an economic assessment, showing the need for new strategies of biomass valorization. One solution could be the development of separation processes for the isolation of secondary plant metabolites, which have been especially valuable for pharmaceutical applications, e.g., taxotere ® and artemisinin. The economic feasibility is demonstrated in a case study, evaluating the purification potential of curcuminoids from Curcuma longa L. Subsequently, the conclusion discusses the limitations of large-scale industrial applications and the need for new separation techniques as a step towards a bio-based world. Full article
(This article belongs to the Special Issue Green Extraction of Natural Products)
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