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Ultrasound- and Microwave-Assisted Extraction of Bioactive Compounds

A topical collection in Molecules (ISSN 1420-3049). This collection belongs to the section "Ultrasound Chemistry".

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Editors

Faculty of Food Technology, Josip Juraj Strossmayer University of Osijek, Osijek, Croatia
Interests: innovative green extraction methods: supercritical CO2 extraction, subritical water extraction, ultrasound- and microwave-assisted extraction of bioactive compounds from different raw materials, and biological investigation of the extracts. Production of high quality powders using spray drying technique and physical-chemical, biochemical, and pharmacological analyses of obtained extracts
Special Issues, Collections and Topics in MDPI journals
Faculty of Technology, University of Novi Sad, Novi Sad, Serbia
Interests: pharmaceutical technologies and chemistry; green extraction technologies (supercritical carbon dioxide, subcritical water, ultrasound- and microwave-assisted extraction); production of dry extracts using spray drying technique, physical-chemical, biochemical, and pharmacological analyses of obtained extracts; valorisation of (food, agricultural, industry, marine, communal) waste/byproducts by applying green engineering
Special Issues, Collections and Topics in MDPI journals

Topical Collection Information

Dear Colleagues,

We are pleased to invite you to submit original articles or reviews to the Special Issue of Molecules entitled “Ultrasound- and Microwave-Assisted Extraction of Bioactive Compounds”.

Microwave- and ultrasonic-assisted technologies represent promising environment-friendly processes that are recognized as highly efficient with regard to time and energy saving and simple manipulation, while providing high process yield and quality of products. These techniques are important in the extraction of bioactive components from various natural resources and in the valorization of different types of waste and byproducts. Moreover, they can be used independently or coupled with other technologies for the separation of bioactive components.

Considering that the constant and ultimate goal is to provide efficient exploitation of natural resources, maximal efficiency, feasibility, and sustainability of the process, and high-quality products, this Special Issue will present an overview of the current state of the field, future developments, and possibilities for application of ultrasound- and microwave-assisted processes.

The Special Issue will cover the following topics:

  • Ultrasound- and microwave-assisted extraction and distillation of bioactive compounds from different sources:
  • Medicinal plants • Food • Food/agricultural waste and byproducts • Marine products • Environmental samples
  • Ultrasound- and microwave-assisted pretreatment
  • Product characterization and application
  • Valorization of waste and/or byproducts
  • Innovative green extraction process design:
  • Optimization study • Intensification of extraction
  • Scale-up of ultrasound and microwave process and challenges
  • Improvement of properties, quality, and safety of the obtained products

We would like to kindly invite and encourage you to submit your original articles or reviews.

We look forward to receiving your work.

Yours sincerely,

Prof. Dr. Stela Jokić
Dr. Jelena Vladić
Collection Editors

Manuscript Submission Information

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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

  • Ultrasound-Assisted Extraction
  • Microwave-Assisted Extraction
  • Bioactivity
  • Valorization of waste and byproducts
  • Optimization
  • Natural products
  • Separation and purification
  • Isolation
  • Sustainability
  • Green chemistry

Published Papers (14 papers)

2024

Jump to: 2022, 2021

17 pages, 4228 KiB  
Article
The Effect of Ultrasound on the Extraction and Functionality of Proteins from Duckweed (Lemna minor)
by Vicente Antonio Mirón-Mérida, Cintya Soria-Hernández, Alejandro Richards-Chávez, Juan Carlos Ochoa-García, Jorge Luis Rodríguez-López and Cristina Chuck-Hernández
Molecules 2024, 29(5), 1122; https://doi.org/10.3390/molecules29051122 - 01 Mar 2024
Viewed by 581
Abstract
The inclusion of protein in the regular human diet is important for the prevention of several chronic diseases. In the search for novel alternative protein sources, plant-based proteins are widely explored from a sustainable and ecological point of view. Duckweed (Lemna minor [...] Read more.
The inclusion of protein in the regular human diet is important for the prevention of several chronic diseases. In the search for novel alternative protein sources, plant-based proteins are widely explored from a sustainable and ecological point of view. Duckweed (Lemna minor), also known as water lentil, is an aquatic plant with potential applications for human consumption due to its protein content and carbohydrate contents. Among all the conventional and novel protein extraction methods, the utilization of ultrasound has attracted the attention of scientists because of its effects on improving protein extraction and its functionalities. In this work, a Box–Behnken experimental design was proposed to optimize the alkaline extraction of protein from duckweed. In addition, an exploration of the effects of ultrasound on the morphological, structural, and functional properties of the extracted protein was also addressed. The optimal extraction parameters were a pH of 11.5 and an ultrasound amplitude and processing time of 60% and 20 min, respectively. These process conditions doubled the protein content extracted in comparison to the value from the initial duckweed sample. Furthermore, the application of ultrasound during the extraction of protein generated changes in the FTIR spectra, color, and structure of the duckweed protein, which resulted in improvements in its solubility, emulsifying properties, and foaming capacity. Full article
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2022

Jump to: 2024, 2021

12 pages, 1517 KiB  
Article
Optimization of Ultrasonic—Assisted Extraction (UAE) Method Using Natural Deep Eutectic Solvent (NADES) to Increase Curcuminoid Yield from Curcuma longa L., Curcuma xanthorrhiza, and Curcuma mangga Val.
by Desy Rosarina, Dimas Rafi Narawangsa, Nabila Shaffa Rizky Chandra, Eka Sari and Heri Hermansyah
Molecules 2022, 27(18), 6080; https://doi.org/10.3390/molecules27186080 - 18 Sep 2022
Cited by 6 | Viewed by 2432
Abstract
This study aims to optimize ultrasonic-assisted natural deep eutectic solvents (NADES) based extraction from C. longa. Choline chloride-lactic acid (CCLA-H2O = 1:1, b/v) was used to investigate the impact of various process parameters such as solvent’s water content, solid loading, [...] Read more.
This study aims to optimize ultrasonic-assisted natural deep eutectic solvents (NADES) based extraction from C. longa. Choline chloride-lactic acid (CCLA-H2O = 1:1, b/v) was used to investigate the impact of various process parameters such as solvent’s water content, solid loading, temperature, and extraction time. The optimal yield of 79.635 mg/g of C. longa was achieved from extraction in 20% water content NADES with a 4% solid loading in 35 °C temperature for 1 h. Peleg’s model was used to describe the kinetics of the optimized ultrasonic-assisted extraction (UAE) method, and the results were found to be compatible with experimental data. The optimum conditions obtained from C. longa extraction were then used for the extraction of C. xanthorriza and C. mangga, which give yields of 2.056 and 31.322 mg/g, respectively. Furthermore, n-hexane was utilized as an anti-solvent in the separation process of curcuminoids extract from C. longa, C. xanthorriza, and C. mangga, which gave curcuminoid recovery of 39%, 0.74%, and 27%, respectively. Solidification of curcuminoids was also carried out using the crystallization method with n-hexane and isopropanol. However, the solution of CCLA and curcuminoids formed a homogeneous mixture with isopropanol. Hence, the curcuminoids could not be solidified due to the presence of NADES in the extract solution. Full article
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16 pages, 1365 KiB  
Article
Ultrasound-Assisted Extraction and Characterization of Polyphenols from Apple Pomace, Functional Ingredients for Beef Burger Fortification
by Luna Pollini, Francesca Blasi, Federica Ianni, Luca Grispoldi, Simone Moretti, Alessandra Di Veroli, Lina Cossignani and Beniamino Terzo Cenci-Goga
Molecules 2022, 27(6), 1933; https://doi.org/10.3390/molecules27061933 - 16 Mar 2022
Cited by 22 | Viewed by 2844
Abstract
Currently, there is an increasing interest to valorise agri-food waste containing bioactive compounds with potential health benefits. In this paper, the recovery of functional molecules from apple pomace, the most abundant by-product of the apple processing industry, was carried out by ultrasound-assisted extraction [...] Read more.
Currently, there is an increasing interest to valorise agri-food waste containing bioactive compounds with potential health benefits. In this paper, the recovery of functional molecules from apple pomace, the most abundant by-product of the apple processing industry, was carried out by ultrasound-assisted extraction (UAE) on fresh and freeze-dried samples. UAE extract, obtained by double extraction of freeze-dried apple pomace, was subjected to chromatographic and spectrophotometric characterization. It showed good levels of total phenol content, high antioxidant activity, and interesting antioxidant compounds (quercetin derivatives, chlorogenic acid, phloridzin). Subsequently, freeze-dried apple pomace, containing 40.19% of dietary fibre, was used as a fortifying agent for beef burgers (4% and 8%). The results concerning colour and sensory analysis of the fortified products were graded even better than the control (0%). The improved fibre and phenol content, together with the neutral flavour, represent the most interesting characteristics of fortified burgers. The results confirm that UAE was a successful technique for extracting phenol compounds and that the addition of apple pomace represents a valid approach to increase the health properties and palatability of beef burgers, including for consumers who do not like meat. Full article
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15 pages, 1058 KiB  
Article
Recovery of Bioactive Ellagitannins by Ultrasound/Microwave-Assisted Extraction from Mexican Rambutan Peel (Nephelium lappaceum L.)
by Luis Estrada-Gil, Juan C. Contreras-Esquivel, Carolina Flores-Gallegos, Alejandro Zugasti-Cruz, Mayela Govea-Salas, Marco A. Mata-Gómez, Raúl Rodríguez-Herrera and Juan A. Ascacio-Valdés
Molecules 2022, 27(5), 1592; https://doi.org/10.3390/molecules27051592 - 28 Feb 2022
Cited by 10 | Viewed by 2773
Abstract
Rambutan (Nephelium lappaceum L.) is a tropical fruit from Asia which has become the main target of many studies involving polyphenolic analysis. Mexico produces over 8 million tons per year of rambutan, generating a huge amount of agro-industrial waste since only the [...] Read more.
Rambutan (Nephelium lappaceum L.) is a tropical fruit from Asia which has become the main target of many studies involving polyphenolic analysis. Mexico produces over 8 million tons per year of rambutan, generating a huge amount of agro-industrial waste since only the pulp is used and the peel, which comprises around 45% of the fruit’s weight, is left behind. This waste can later be used in the recovery of polyphenolic fractions. In this work, emerging technologies such as microwave, ultrasound, and the hybridization of both were tested in the extraction of phenolic compounds from Mexican rambutan peel. The results show that the hybrid technology extraction yielded the highest polyphenolic content (176.38 mg GAE/g of dry rambutan peel). The HPLC/MS/ESI analysis revealed three majoritarian compounds: geraniin, corilagin, and ellagic acid. These compounds explain the excellent results for the biological assays, namely antioxidant activity evaluated by the DPPH, ABTS, and LOI (Lipid oxidation inhibition) assays that exhibited great antioxidant capacity with IC50 values of 0.098, 0.335, and 0.034 mg/mL respectively, as well as prebiotic activity demonstrated by a µMax (maximum growth) of 0.203 for Lactobacillus paracasei. Lastly, these compounds have shown no hemolytic activity, opening the door for the elaboration of different products in the food, cosmetic, and pharmaceutical industries. Full article
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13 pages, 1002 KiB  
Article
Effect of Ultrasound-Assisted, Microwave-Assisted and Ultrasound-Microwave-Assisted Extraction on Pectin Extraction from Industrial Tomato Waste
by Patareeya Lasunon and Nipaporn Sengkhamparn
Molecules 2022, 27(4), 1157; https://doi.org/10.3390/molecules27041157 - 09 Feb 2022
Cited by 27 | Viewed by 3143
Abstract
This work aimed to study the effect of ultrasound-assisted (UAE), microwave-assisted (MAE), and ultrasound-microwave-assisted (UMAE) methods for pectin extraction from industrial tomato waste. The overall performance index from the fuzzy analytical method with three criteria, pectin yield, galacturonic acid, and lycopene content, was [...] Read more.
This work aimed to study the effect of ultrasound-assisted (UAE), microwave-assisted (MAE), and ultrasound-microwave-assisted (UMAE) methods for pectin extraction from industrial tomato waste. The overall performance index from the fuzzy analytical method with three criteria, pectin yield, galacturonic acid, and lycopene content, was applied to evaluate the best extraction conditions by using the weight of 75, 20, and 5, respectively. The UAE conditions was performed at a temperature of 80 °C for 20 min with the variations in the extraction pH and the solid liquid (SL) ratio. The best UAE conditions with high pectin yield, and high total carboxyl group, as well as a lycopene content, was the pH of 1.5 and the SL ratio of 1:30. The MAE conditions was performed with variations in the microwave powers and times. The results showed that the best MAE conditions were 300 W for 10 min, which gave high pectin yield with high galacturonic acid and lycopene content. Various conditions of UMAE at the best conditions of MAE and UAE were performed and exhibited that the UAE had more positively affected the pectin yield. However, the FTIR spectra of obtained pectins from different extraction techniques showed a similar pectin structure. Full article
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2021

Jump to: 2024, 2022

15 pages, 800 KiB  
Article
Microwave-Assisted Extraction of Phenolic Compounds from Spent Coffee Grounds. Process Optimization Applying Design of Experiments
by José P. Coelho, Maria P. Robalo, Stanislava Boyadzhieva and Roumiana P. Stateva
Molecules 2021, 26(23), 7320; https://doi.org/10.3390/molecules26237320 - 02 Dec 2021
Cited by 11 | Viewed by 2994
Abstract
In this study, sustainable technology microwave-assisted extraction (MAE) in association with green solvents was applied to recover phenolic compounds from spent coffee grounds (SCGs). A design of experiments (DOE) was used for process optimization. Initially, a 24−1 two level Fractional Factorial Design [...] Read more.
In this study, sustainable technology microwave-assisted extraction (MAE) in association with green solvents was applied to recover phenolic compounds from spent coffee grounds (SCGs). A design of experiments (DOE) was used for process optimization. Initially, a 24−1 two level Fractional Factorial Design was used and ratios “solvent to solute” and “ethanol to water” were identified as the significant experimental factors. Consequently, Central Composite Design (CCD) was applied to analyze the effects of the significant variables on the response yield, total polyphenols content (TPC), and antioxidant activity (AA) by the DPPH assay method, and quadratic surfaces to optimize those responses were generated. The values of the significant factors of 16.7 (solvent/solute) and 68.9% (ethanol/water) were optimized simultaneously the yield (%) at 6.98 ± 0.27, TPC (mg GAE/g) at 117.7 ± 6.1, and AA (µmol TE/g) at 143.8 ± 8.6 and were in excellent agreement with those predicted from the CCD model. The variations of the compositions of the lipids, caffeine, pentacyclic diterpenes, and FAME as a function of the dominant factor % ethanol in the solvent mixture were analyzed by applying NMR and GC-FID, and the results obtained confirmed their determinative significance. Full article
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16 pages, 966 KiB  
Article
Phenolic Profile, Antioxidant Capacity and Antimicrobial Activity of Nettle Leaves Extracts Obtained by Advanced Extraction Techniques
by Ivona Elez Garofulić, Valentina Malin, Maja Repajić, Zoran Zorić, Sandra Pedisić, Meta Sterniša, Sonja Smole Možina and Verica Dragović-Uzelac
Molecules 2021, 26(20), 6153; https://doi.org/10.3390/molecules26206153 - 12 Oct 2021
Cited by 20 | Viewed by 3070
Abstract
Nettle is a widely known plant whose high biological activity and beneficial medicinal effects are attributed to various bioactive compounds, among which polyphenols play an important role. In order to isolate polyphenols and preserve their properties, advanced extraction techniques have been applied to [...] Read more.
Nettle is a widely known plant whose high biological activity and beneficial medicinal effects are attributed to various bioactive compounds, among which polyphenols play an important role. In order to isolate polyphenols and preserve their properties, advanced extraction techniques have been applied to overcome the drawbacks of conventional ones. Therefore, microwave-assisted extraction (MAE) has been optimized for the isolation of nettle leaves polyphenols and it was compared to pressurized liquid extraction (PLE) and conventional heat-reflux extraction (CE). The obtained extracts were analyzed for their individual phenolic profile by UPLC MS2 and for their antioxidant capacity by ORAC assay. MAE proved to be the more specific technique for the isolation of individual phenolic compounds, while PLE produced extracts with higher amount of total phenols and higher antioxidant capacity. Both techniques were more effective compared to CE. PLE nettle extract showed antimicrobial activity against bacteria, especially against Gram-negative Pseudomonas fragi ATCC 4973 and Campylobacter jejuni NCTC 11168 strains. This suggests that PLE is suitable for obtaining a nettle extract with antioxidant and antimicrobial potential, which as such has great potential for use as a value-added ingredient in the food and pharmaceutical industry. Full article
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12 pages, 1236 KiB  
Article
A Fast and Efficient Ultrasound-Assisted Extraction of Tocopherols in Cow Milk Followed by HPLC Determination
by Archimede Rotondo, Giovanna Loredana La Torre, Teresa Gervasi, Giacomo di Matteo, Mattia Spano, Cinzia Ingallina and Andrea Salvo
Molecules 2021, 26(15), 4645; https://doi.org/10.3390/molecules26154645 - 30 Jul 2021
Cited by 6 | Viewed by 2165
Abstract
A fast HPLC method with fluorescence detector (FD) was developed for the determination of three tocopherols (TOCs) in milk samples from Modicana cattle breed. The ultrasound-assisted procedure was optimized for the extraction of TOCs prior to HPLC/FD analysis, reducing sample preparation time and [...] Read more.
A fast HPLC method with fluorescence detector (FD) was developed for the determination of three tocopherols (TOCs) in milk samples from Modicana cattle breed. The ultrasound-assisted procedure was optimized for the extraction of TOCs prior to HPLC/FD analysis, reducing sample preparation time and allowing a fast quantification of α-tocopherol, δ-tocopherol and γ tocopherol. The optimized ultrasonic extraction combines an efficient and simple saponification at room temperature and a rapid HPLC quantification of TOCs in milk. The precision of the full analytical procedure was satisfactory and the recoveries at three spiked levels were between 95.3% and 87.8%. The linear correlations were evaluated (R2 > 0.99) and the relative standard deviation (RSD) values for intra-day and inter-day tests at three spiked levels were below 1% for the retention time and below 5.20% for the area at low level spiking. The proposed procedure, reducing the experimental complexity, allowed accurate extraction and detection of three TOCs in milk samples from Modicana cattle breed. Full article
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9 pages, 1288 KiB  
Article
Fatty Acid Ethyl Esters (FAEE): A New, Green and Renewable Solvent for the Extraction of Carotenoids from Tomato Waste Products
by Aurel Diacon, Ioan Călinescu, Mircea Vinatoru, Petre Chipurici, Alexandru Vlaicu, Aurelian Cristian Boscornea and Timothy J. Mason
Molecules 2021, 26(14), 4388; https://doi.org/10.3390/molecules26144388 - 20 Jul 2021
Cited by 9 | Viewed by 3648
Abstract
Currently there is a drive towards the minimisation and reclamation of valuable materials from the waste products of the food and beverage industry. This can be achieved through the extraction of residual nutraceuticals from such materials. Tomato pomace contains carotenoids and other chemicals [...] Read more.
Currently there is a drive towards the minimisation and reclamation of valuable materials from the waste products of the food and beverage industry. This can be achieved through the extraction of residual nutraceuticals from such materials. Tomato pomace contains carotenoids and other chemicals which can be extracted directly into edible oils to improve the health-giving properties of such oils. We report here a novel green solvent, fatty acid ethyl esters (FAEE), which is significantly more effective than sunflower oil and hexane for the extraction of lycopene and beta-carotene from tomato skin waste. FAEE are a non-toxic renewable resource that is environmentally friendly and to our knowledge has never been used as a vegetal extraction fluid. The efficiency of FAEE extraction was significantly improved relative to both sunflower oil and hexane under ultrasound-assisted extraction (UAE) conditions. In addition, FAEE have the additional and significant advantage that once enriched with the extracted nutraceuticals can be used directly as a food additive. Full article
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11 pages, 1524 KiB  
Article
Valorization of Artichoke Industrial By-Products Using Green Extraction Technologies: Formulation of Hydrogels in Combination with Paulownia Extracts
by Gabriela Órbenes, Paula Rodríguez-Seoane, María Dolores Torres, Rolando Chamy, María Elvira Zúñiga and Herminia Domínguez
Molecules 2021, 26(14), 4386; https://doi.org/10.3390/molecules26144386 - 20 Jul 2021
Cited by 12 | Viewed by 2339
Abstract
The integral valorization of artichoke bracts generated during industrial canning of artichoke was assessed. The extraction of bioactive compounds was addressed with pressurized hot water under subcritical conditions. The performance of this stage on the extraction of phenolics with antioxidant properties and the [...] Read more.
The integral valorization of artichoke bracts generated during industrial canning of artichoke was assessed. The extraction of bioactive compounds was addressed with pressurized hot water under subcritical conditions. The performance of this stage on the extraction of phenolics with antioxidant properties and the saccharidic fraction using conventional and microwave heating was compared. The microwave assisted process was more efficient than the conventional one regarding extraction yields of total solubles, and glucose and fructose oligomers and phenolics, because lower operational temperatures and shorter times were needed. Degradation of fructose oligomers was observed at temperatures higher than 160 °C, whereas the maximal phenolic content occurred at 220 °C. Both the extracts and the residual solids, obtained at conditions leading to maximum phenolics yields, were evaluated for the production of starch-based hydrogels, supplemented with Paulownia leaves’ aqueous extracts. Full article
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14 pages, 5713 KiB  
Article
Optimization of MAE for the Separation of Nicotine and Phenolics from Tobacco Waste by Using the Response Surface Methodology Approach
by Marija Banožić, Ines Banjari, Ivana Flanjak, Mate Paštar, Jelena Vladić and Stela Jokić
Molecules 2021, 26(14), 4363; https://doi.org/10.3390/molecules26144363 - 19 Jul 2021
Cited by 3 | Viewed by 3263
Abstract
This study intends to valorize by-products of the industrial processing of tobacco to obtain nicotine and phenolics as value-added compounds. Three influential parameters of the microwave-assisted extraction-MAE (temperature, treatment time, and solvent/solid ratio) were studied for the optimization of the extraction protocol for [...] Read more.
This study intends to valorize by-products of the industrial processing of tobacco to obtain nicotine and phenolics as value-added compounds. Three influential parameters of the microwave-assisted extraction-MAE (temperature, treatment time, and solvent/solid ratio) were studied for the optimization of the extraction protocol for tobacco leaves and three types of waste—scrap, dust, and midrib, respectively. Nicotine was the dominant bioactive compound in all extracts, ranging from 1.512 to 5.480% in leaves, 1.886 to 3.709% in scrap, 2.628 to 4.840% dust, and 0.867 to 1.783% in midrib extracts. Five phenolic compounds were identified and quantified, predominated by chlorogenic acid and rutin. Additionally, total phenol content and antioxidant activity were determined using spectrophotometric assays. Optimization was performed in two aspects: to obtain a maximum extraction yield with minimum nicotine content and to obtain a maximum extraction yield with maximum nicotine content. These findings demonstrate that tobacco waste is a valuable source of bioactive compounds and MAE can be a promising alternative technique to obtain extracts rich in targeted bioactive compounds, especially nicotine. Full article
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13 pages, 2811 KiB  
Article
Optimization of Ultrasound-Assisted Extraction of Phenolics from Sideritis raeseri Using Response Surface Methodology
by Katarina Šavikin, Jelena Živković, Teodora Janković, Nada Ćujić-Nikolić, Gordana Zdunić, Nebojša Menković and Zorica Drinić
Molecules 2021, 26(13), 3949; https://doi.org/10.3390/molecules26133949 - 28 Jun 2021
Cited by 6 | Viewed by 2100
Abstract
In this study we define the optimal conditions for ultrasound-assisted extraction of bioactive polyphenols from S. raeseri aerial parts using response surface methodology. The influence of ethanol concentration (10–90%), extraction temperature (20–80 °C), extraction time (10–60 min), and solid-to-solvent ratio (1:10–1:50) on total [...] Read more.
In this study we define the optimal conditions for ultrasound-assisted extraction of bioactive polyphenols from S. raeseri aerial parts using response surface methodology. The influence of ethanol concentration (10–90%), extraction temperature (20–80 °C), extraction time (10–60 min), and solid-to-solvent ratio (1:10–1:50) on total phenolic content as well as on content of individual flavonoids, and hypolaetin and isoscutellarein derivatives was studied. For the experimental design, a central composite design was chosen. In the obtained extracts, the following ranges of targeted compounds were detected: total phenol from 19.32 to 47.23 mg GAE/g dw, HYP from 1.05 to 11.46 mg/g dw, ISC 1 from 0.68 to 10.68 mg/g dw, and ISC 2 from 0.74 to 15.56 mg/g dw. The optimal extraction conditions were set as: ethanol concentration of 65%, extraction time of 50 min, extraction temperature of 63 °C, and solid-to-solvent ratio of 1:40. Contents of TP, HYP, ISC 1, and ISC 2 in optimal extracts were 47.11 mg GAE/g dw, 11.73 mg/g dw, 9.54 mg/g dw, and 15.40 mg/g dw, respectively. Experimentally set values were in good agreement with those predicted by the response surface methodology model, indicating suitability of the used model, as well as the success of response surface methodology in optimizing the conditions of the extraction. Full article
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15 pages, 1148 KiB  
Article
Ultrasound as a Promising Tool for the Green Extraction of Specialized Metabolites from Some Culinary Spices
by Jana Šic Žlabur, Marko Brajer, Sandra Voća, Ante Galić, Sanja Radman, Suzana Rimac-Brnčić, Qiang Xia, Zhenzhou Zhu, Nabil Grimi, Francisco J. Barba and Nataša Hulak
Molecules 2021, 26(7), 1866; https://doi.org/10.3390/molecules26071866 - 25 Mar 2021
Cited by 10 | Viewed by 2827
Abstract
Spices are a popular food of plant origin, rich in various phytochemicals and recognized for their numerous properties. The aim of the study was to evaluate the antioxidant and antimicrobial activity, as well as the content of specialized metabolites, of aqueous extracts of [...] Read more.
Spices are a popular food of plant origin, rich in various phytochemicals and recognized for their numerous properties. The aim of the study was to evaluate the antioxidant and antimicrobial activity, as well as the content of specialized metabolites, of aqueous extracts of three spice species––garlic (Allium sativum L.), ginger (Zingiber officinalle L.) and turmeric (Curcuma longa L.)––prepared by green extraction methods. Ultrasound treatment increased the chromaticity parameter b value of turmeric and ginger extracts, thus indicating a higher yellow color predominantly due to curcuminoids characteristic of these species. Ultrasound-assisted extraction significantly increased the content of total soluble solids, phenolic compounds, total carotenoids and vitamin C. The temperature of the system was also an important factor, with the highest (70 °C) conditions in ultrasound-assisted extraction having a positive effect on thermolabile compounds (vitamin C, phenolics, total carotenoids). For example, turmeric extract treated with ultrasound at 70 °C had up to a 67% higher vitamin C content and a 69.4% higher total carotenoid content compared to samples treated conventionally at the same temperature, while ginger extracts had up to 40% higher total phenols. All different concentrations of spice extracts were not sufficient for complete inhibition of pathogenic bacterial strains of Salmonella, L. monocytogenes and S. aureus; however, only garlic extracts had an effect on slowing down the growth and number of L. monocytogenes colonies. Spice extracts obtained by ultrasonic treatment contained a significantly higher level of bioactive compounds and antioxidant capacity, suggesting that the extracts obtained have significant nutritional potential and thus a significant possibility for phytotherapeutic uses. Full article
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13 pages, 12155 KiB  
Article
Microwave-Assisted Extraction of Curcuma longa L. Oil: Optimization, Chemical Structure and Composition, Antioxidant Activity and Comparison with Conventional Soxhlet Extraction
by Rut Fernández-Marín, Susana C. M. Fernandes, María A. Andrés and Jalel Labidi
Molecules 2021, 26(6), 1516; https://doi.org/10.3390/molecules26061516 - 10 Mar 2021
Cited by 25 | Viewed by 4912
Abstract
Curcuma root (Curcuma longa L.) is a very important plant in gastronomy and medicine for its unique antiseptic, anti-inflammatory, antimicrobial and antioxidant properties. Conventional methods for the extraction of curcuma oil require long extraction times and high temperatures that can degrade the [...] Read more.
Curcuma root (Curcuma longa L.) is a very important plant in gastronomy and medicine for its unique antiseptic, anti-inflammatory, antimicrobial and antioxidant properties. Conventional methods for the extraction of curcuma oil require long extraction times and high temperatures that can degrade the active substances. Therefore, the objectives of the present study were: (i) first, to optimize the extraction yield of curcuma oil by applying a Box-Behnken experimental design using surface response methodology to the microwave-assisted extraction (MAE) technique (the independent variables studied were reaction time (10–30 min), microwave power (150–200 W) and curcuma powder/ethanol ratio (1:5–1:20; w/v); and, (ii) second, to assess the total phenolic content (TPC) and their antioxidant activity of the oil (at the optimum conditions point) and compare with the conventional Soxhlet technique. The optimum conditions for the MAE were found to be 29.99 min, 160 W and 1:20 w/v to obtain an optimum yield of 10.32%. Interestingly, the oil extracted by microwave-assisted extraction showed higher TPC and better antioxidant properties than the oil extracted with conventional Soxhlet technique. Thus, it was demonstrated that the method applied for extraction influences the final properties of the extracted Curcuma longa L. oil. Full article
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