Extraction of essential oils from Mentha piperita using advanced techniques: Microwave versus ohmic assisted hydrodistillation

Ohmic and microwave assisted hydrodistillation (OAHD and MAHD, respectively) are advanced hydrodistillation (HD) techniques utilizing ohmic and microwave heating processes for extraction of essential oils. OAHD and MAHD of essential oils from the aerial parts of peppermint were studied and the results were compared with those of the traditional HD. The results showed that OAHD and MAHD methods require less than half an hour for extraction process while HD require about 1 h. Scanning electron microscopy of mint leaves undergone OAHD and MAHD provided evidences as to a sudden rupture of essential oil glands. GC–MS analysis did not indicate any noticeable changes in the compounds of the essential oils obtained by novel studied methods in comparison with HD. The results introduced OAHD as the greenest technique in terms of energy consumption. MAHD was superior in terms of rate of essential oils accumulation and also extraction duration parameter.     

Microwave‐assisted hydrodistillation of essential oil from Zataria multiflora Boiss

Microwave‐assisted hydrodistillation (MAHD) has recently gained attention for the extraction of essential oils. A concern with the use of MAHD is the possibility of sample deterioration during the extended exposure to microwave irradiation. In this study, MAHD was applied as a new and green technology for the extraction of essential oil from Zataria multiflora Boiss. (Shirazi thyme) aerial parts. Superior results were obtained with the proposed method in terms of extraction time [1 h vs. 4 h in hydrodistillation (HD)] for an essential oil recovery of 3.66 and 3.44%, respectively. Images obtained from thyme leaves using scanning electron microscopy indicated a sudden eruption of essential oil glands undergoing MAHD. GC‐MS analysis of the essential oils did not indicate any new or missing compounds in the essential oil obtained by MAHD in comparison with that by HD. Therefore, a microwave oven can be safely used for the extraction of essential oil from Shirazi thyme.     

Comparative Study of Essential Oils Extracted from Algerian Myrtus communis L. Leaves Using Microwaves and Hydrodistillation

Two different extraction methods were used for a comparative study of Algerian Myrtle leaf essential oils: solvent-free-microwave-extraction (SFME) and conventional hydrodistillation (HD). Essential oils analyzed by GC and GC-MS presented 51 components constituting 97.71 and 97.39% of the total oils, respectively. Solvent-Free-Microwave-Extract Essential oils SFME-EO were richer in oxygenated compounds. Their major compounds were 1,8-cineole, followed by α-pinene as against α-pinene, followed by 1,8-cineole for HD. Their antimicrobial activity was investigated on 12 microorganisms. The antioxidant activities were studied with the 2,2-diphenyl-1-picrylhydrazyl (DPPH^•) radical scavenging method. Generally, both essential oils showed high antimicrobial and weak antioxidant activities. Microstructure analyses were also undertaken on the solid residue of myrtle leaves by Scanning Electronic Microscopy (SEM); it showed that the SFME-cellular structure undergoes significant modifications compared to the conventional HD residual solid. Comparison between hydrodistillation and SFME presented numerous distinctions. Several advantages with SFME were observed: faster kinetics and higher efficiency with similar yields: 0.32% dry basis, in 30 min as against 180 min for HD.     

Extraction of Essential Oil from Laurel Leaves by Using Microwaves

Abstract

The effects of microwave power and time in solvent-free microwave extraction (SFME) on the yield and composition of the essential oil obtained from laurel (Laurus nobilis L.) leaves were studied. The extraction was also performed by hydrodistillation as a control. Specific gravities and refractive indices of the essential oils obtained by different methods and at various conditions were also examined. The main constituent of laurel essential oil was 1,8-cineole (630–730 mg/mL). Essential oils obtained by SFME and hydrodistillation were comparable with respect to both yield and composition while the process time was reduced by 55–60% when SFME was used.     

A new kinetic model for the common juniper essenstial oil extraction by microwave hydrodistillation

The main objective of the present study was to model the kinetics of essential oil extraction from swelled ground juniper berries by classic hydrodistillation (HD) and microwave-assisted hydrodistillation (MAHD). A new phenomenological kinetic model was developed on the basis of the juniper essential oil extraction mechanism that assumed three mass transfer processes occurring simultaneously: washing, unhindered diffusion and hindered diffusion. The new model was compared to the existing kinetic models. Among the tested models, the new model had the smallest mean relative percentage deviation and the highest corrected Akaike information criterion value. In addition, that, the new model was verified for HD and MAHD of essential oils from some other plant materials. On the basis of the above-mentioned facts, the new model can be recommended for modeling the kinetics of essential oil extraction by both HD and MAHD.     

Enhanced extraction of essential oil from Cinnamomum cassia bark by ultrasound assisted hydrodistillation

Cinnamon essential oil with many bioactivities is an important raw material for the production of various chemicals,and the conventional hydrodistillation(HD) for cinnamon oil extraction always require a longer extraction time. In this work, ultrasound-assisted hydrodistillation extraction(UAHDE) technique was employed to enhance the extraction efficiency of essential oils from cinnamon barks. The parameters with significant effects on the essential oil extraction efficiency(ultrasound time, ultrasound power, extraction time, liquid–solid ratio) were optimized, and the proposed UAHDE was compared with the conventional HD extraction in terms of the extraction time, extraction yield, and physicochemical properties of extracted oils. Compared to the HD extraction, the UAHDE resulted in a shorter extraction time and a higher extraction yield. Using GC–MS analysis, the UAHDE provided more valuable essential oil with a high content of the vital trans-cinnamaldehyde compounds compared with the HD. Scanning electron micrograph(SEM) confirmed the efficiency of ultrasound irradiation for cinnamon oil extraction. In addition, the analysis of electric consumption and CO2 emission shows that the UAHDE process is a more economic and environment-friendly approach. Thus, UAHDE is an efficient and green technology for the cinnamon essential oil extraction, which could improve the quantity and quality of cinnamon oils.     

微波、超声波和水蒸气蒸馏在紫苏籽挥发油分析中的对比研究

采用水蒸气蒸馏法、微波提取和超声波萃取紫苏籽挥发油。运用毛细管气相色谱-质谱联用仪结合计算机检索对所得挥发油成分进行分析和鉴定,用气相色谱峰面积归一法测定各组分的相对质量分数。结果表明,3种方法分别从紫苏籽所得挥发油中鉴定出33、31及29种化合物,各占总峰面积的97.16%、97.38%及96.6%。不同方法所得紫苏籽挥发油化学组成各有异同,但主要成分是正十六酸、(Z,Z,Z)-9,12,15-十八三烯-1-醇和戊基-2-呋喃基酮。     

Optimization of Ultrasonic Enhanced Salt‐Containing Hydrodistillation by Response Surface Methodology

An ultrasonic enhanced salt‐containing hydrodistillation (UESHD) method for separating essential oil from lavender (Lavandula angustifolia) flowers was investigated using response surface methodology (RSM). The experimental data obtained from a 27‐run experiment were fitted to a second‐order polynomial equation. The optimal conditions were determined by the 3D response surface and the contour plots derived from the models. The efficiency of UESHD and conventional hydrodistillation (HD) was compared. The extraction yield of UESHD was two‐fold higher than that of HD. In addition, GC‐MS results indicated some differences in composition and content between the two essential oils from UESHD and HD.     

不同方法提取鸦胆子挥发油化学成分的GC-MS分析

分别采用水蒸气蒸馏法(HD)和微波辅助水蒸气蒸馏法(MAHD)提取鸦胆子挥发油。运用毛细管气相色谱-质谱联用仪结合计算机检索对所得挥发油成分进行分析和鉴定,用气相色谱面积归一法测定各组分的相对质量分数。结果显示,两种方法分别从鸦胆子挥发油中鉴定出42种和37种化合物,分别占总峰面积的94.09%和94.13%。不同方法所得鸦胆子挥发油化学组成不同,但主要成分是黄樟脑、(+)-4-蒈烯、β-香叶烯、丁香油酚甲醚、2,6-二甲氧基甲苯、柠檬烯和甲基胡椒酚。     

Subcritical water extraction of essential oil from Aquilaria malaccensis leaves

ABSTRACT

Hydro-distillation (HD) has been widely used in the extraction of essential oil, yet it is a low efficient method that consumes time and energy. In this work, A. malaccensis’ oils have been extracted using subcritical water extraction (SCWE) from its leaves to determine the optimum parameters using analysis of variance. Quadratic model was deduced to be most suitable to analyze SCWE parameters. Regression analysis indicated that interaction of temperature and reaction time parameters exerted great influence on the yield. Kinetic modeling was conducted to study SCWE’s mechanism, and second-order model was concluded to be the best model for SCWE. Optimum extraction conditions of essential oil were 156°C, 0.2 w/w, 25 min. Gas chromatography/mass spectroscopy characterization was conducted and results indicated that the quality of A. malaccensis’ leaves oils extracted by SCWE significantly improved compared to previous studies. Additionally, the essential oils extracted by SCWE contained several value-added compounds useful in medicine such as furfural and guaiacol. Fourier transform infrared, scanning electron microscopy, and Brunauer–Emmett–Teller and Barrett–Joyner–Halenda on the leaves samples provided further evidence for better performance of SCWE, as the sample’s pores, cell walls, cellulose, and hemicellulose were more damaged. The result showed that compared to extraction yield of HD method, that of SCWE was 2.5 times higher, while the requiring time was 8.4 times shorter. Therefore, it was concluded that SCWE is a better extraction method in terms of time, efficiency, yield, and quality.     

Effects of Operating Parameters on the Cinnamaldehyde Content of Extracted Essential Oil Using Various Methods

Supercritical fluid extraction (SFE) of essential oils from commercial cinnamon bark was compared with essential oils that were obtained by hydrodistillation. Effects of operating parameters (pressure, temperature and extraction time of SFE) on the extraction yield and the composition of the extracted volatile oil were studied. Moreover, in the hydrodistillation process, the effect of the pH of the solvent on the concentration of cinnamaldehyde in the extracted volatile oil was studied. The maximum yield of extract in the SFE process is about 7.8 % at 70 °C and 240 bar. The maximum concentration of cinnamaldehyde in the SFE process was obtained at 70 °C and 160 bar, and the maximum concentration of this component in hydrodistillation was achieved at pH = 4.1.     

Antioxidant and Antibacterial Activity of Nutraceutical Compounds from Chlorella vulgaris Extracted in Hydrothermal Condition

Abstract

Water in hydrothermal condition has been used for extraction of nutraceutical compounds from Chlorella vulgaris. Hydrothermal extraction was carried out in a semi-batch and a batch extractor at various temperatures (120–200°C), pressures (2–10 MPa), and extraction times (30–300 min) to extract antioxidant and antibacterial compounds. The effect of extraction condition on the yield of extract was investigated. The antioxidant and antibacterial activity of extracts obtained by hydrothermal extraction were examined. The increasing extraction temperature resulted in higher antioxidant activity, but lower antimicrobial activity. As comparison with hot water extraction, the antioxidant activity of extract obtained by hydrothermal extraction was higher than that obtained by hot water extraction, but the antibacterial activity of the extract obtained by hydrothermal extraction was lower.     

Antiradical Efficiency of Essential Oils from Plant Seeds Obtained by Supercritical CO2, Soxhlet Extraction,and Hydrodistillation

The effect of supercritical CO₂ (SCCO₂) extraction conditions (pressure and temperature) on the system performance as well as the antiradical efficiencies of the essential oils from Japanese pepper (Xanthoxylum piperitum DC.), cardamom (Elettaria cardamomum Maton), and fennel (Foeniculum vulgare) seeds were investigated. A control study with the conventional Soxhlet extraction and hydrodistillation was also conducted to compare the performance of those processes. Antiradical efficiencies were investigated by utilizing 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay with a UV-vis spectrophotometer. Higher pressure and temperature had positive effects on the supercritical process performance due to higher CO₂ density and substrate solubility in SCCO₂. Antiradical efficiencies of cardamom and pepper were almost the same, being significantly higher than that of fennel seeds. However, this effect decreased dramatically for all the spices when the extraction method was changed to Soxhlet extraction and hydrodistillation. SCCO₂ extraction was found to yield more quality and effective essential oils than Soxhlet extraction and hydrodistillation.     

Optimization of ethanol modified supercritical carbon dioxide on the extract yield and antioxidant activity from Biebersteinia multifida DC

Essential oil of Biebersteinia multifida DC cultivated in Iran was obtained by hydrodistillation (HD) and supercritical fluid extraction (SFE) methods. The oil was analyzed by capillary gas chromatography using flame ionization and mass spectrometric detections. The effects of different parameters such as temperature, pressure, static extraction time, dynamic extraction time, and mole fraction of modifier on the supercritical fluid extraction (SFE) and radical scavenging activity of B. multifida oil were optimized using central composite design. Fifty two compounds were identified in the HD oil. The major components of B. multifida were (E)-Nerolidol (31.45%), Hexadecanoic acid (11.84%), Phytol (17.1%), and 6,10,14-trimethyl-2-pentadecanone (15.4%). However, by using supercritical carbon dioxide in optimum conditions, obtained only four components contain more than 91.74% of the essential oil. The optimum extraction yield and DPPH EC₅₀ via SFE method were 96% (w/w) and 27.19, respectively.     

Optimization of pressurized hot water extraction on the extract yield and antioxidant activity from Biebersteinia multifida DC using a modified supercritical fluid extractor

Essential oil of Biebersteinia multifida DC cultivated in Iran was obtained by hydrodistillation (HD) and pressurized hot water extraction (PHWE) methods. The oil was analyzed by capillary gas chromatography using flame ionization and mass spectrometric detections. The effects of different parameters such as temperature, pressure, static extraction time, dynamic extraction time, and flow rate on the PHWE and radical scavenging activity of B. multifida oil were optimized using circumscribed central composite. Fifty two compounds were identified in the HD oil. The major components of B. multifida were (E)-Nerolidol (31.45%), Hexadecanoic acid (11.84%), Phytol (17.1%), and 6,10,14-trimethyl-2-pentadecanone (15.4%). However, by using pressurized hot water extraction in optimum conditions, obtained only four components contain more than 86% of the essential oil. The optimum extraction yield and DPPH EC₅₀ via PHWE method were 5.1% (w/w) and 28.40, respectively.     

A predictive approach in modeling and simulation of heat and mass transfer during microwave heating. Application to SFME of essential oil of Lavandin Super

Solvent Free Microwave Extraction (SFME) is a new and faster process with higher energy efficiency used to extract essential oils. Nevertheless, so far no modeling efforts have been found on the subject. In this work a predictive modeling approach to the microwave extraction of essential oils applied to the SFME is proposed. The model includes the interaction between electromagnetic energy and the material through the use of Maxwell's equations together with estimation of the dielectric constants. The evaporation of water from the plant is also simulated. The results indicate that it is possible to model this process with a predictive approach of the properties of the system. The microwave heating is underpredicted in the area closer to the walls, thus the evaporation resulting in simulations is lower than the measured values. Nevertheless, the results show a behavior very similar to the experimental values.     

Supercritical fluid extraction of wormwood (Artemisia absinthium L.)

The objective of the work was to optimize the extraction of wormwood oil by supercritical fluid extraction (SFE) of growth-controlled plant material. Different extraction conditions, two growth techniques and various crops were tested and the evolution of the extracted oil composition was screened chromatographically. A comparison with conventional techniques such as hydrodistillation (HD) or organic solvent extraction (OSE) was also presented. Particularly, six CO₂ densities ranging from 285.0 kg/m³ to 819.5 kg/m³ were studied in the range of 9.0-18.0 MPa and 40-50 °C. A systematic study was carried out with plant material from 2005, while SFE of 2006, 2008 and aeroponically grown crops was performed for comparative purposes. The effect of ethanol as a modifier of the supercritical fluid extraction was also studied. The major compounds found in the SFE extracts as well as in the HD essential oils were Z-epoxyocimene, chrysanthenol and chrysanthenyl acetate. A model based on mass transfer equations, the Sovová model, was successfully applied to correlate the experimental data.     

Extraction of essential oil from geranium (Pelargonium graveolens) with supercritical carbon dioxide

This study investigated the supercritical fluid extraction (SFE) of geranium essential oil from geranium (Pelargonium graveolens) using supercritical carbon dioxide solvent. The extraction yield was measured as a function of pressure, temperature and carbon dioxide flow rate. At low pressure (10 MPa) and high temperature (343 K), waxes were co‐extracted with the essential oil, resulting in artificially elevated essential oil extraction yields as no method was available with the SFE apparatus used to separate co‐extracted waxes and oil. At high pressure (30 MPa) and low temperature (313 K), the amount of wax co‐extracted decreased. Under these ‘optimum’ conditions, the extraction yield increased with decrease in flow rate giving a maximum extraction yield of 2.53%. All samples were analyzed by gas chromatography–mass spectrometry and the effect of pressure and extraction time on oil composition was studied. The percentage compositions of terpene hydrocarbons, terpenols, geraniol and geranyl esters were significantly affected by pressure and extraction time. The oil samples obtained by SFE were also compared with commercially obtained steam distilled samples. All major components of the commercially obtained oils were present in the SFE‐obtained oils; however, the percentage composition of the major components differed greatly between steam distilled and SFE oils. Copyright © 2005 Society of Chemical Industry     

微波无溶剂提取的应用进展

微波无溶剂提取法是近年发展起来的一种用于提取植物挥发油及其它具有挥发性固体样品的新技术。具有快速、简便、无需溶剂、环保节能等优点,近年来得到广泛应用。文章总结了微波无溶剂提取技术的基本原理及其近年来的应用进展。     

Antibacterial polymer composites based on low‐density polyethylene and essential oils immobilized on various solid carriers

In this study, we investigated the antibacterial modification of polymers with biologically active substances in essential oils [EOs; linalool, 4‐allylanisole (ALY), and trans‐anethole]. These compounds were thermoplastically incorporated into a low‐density polyethylene matrix via solid inert carriers [wood flour (WF) and talc and molecular sieves] with physically immobilized EOs. The concentrations of the antibacterial modifiers on the carriers and in the resulting composites were determined with three chromatographic techniques (gas chromatography with mass spectrometry, pyrolysis and gas chromatography with mass spectrometry, and high‐performance liquid chromatography). The effects of such modifications to the mechanical properties of the prepared composites were studied by stress–strain analysis. Interactions on the polymer matrix carriers were observed by scanning electron microscopy. The prepared composites were also tested for antibacterial activity against both Gram‐negative and Gram‐positive bacterial strains. The highest efficiency of isothermal immobilization was found for systems consisting of ALY and WF. This finding was in accordance with microbiological studies. The phase of immobilizing the EOs did not influence the mechanical properties of the studied composites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42816.