Solvent-free Microwave Extraction Method Research Articles

Chemical Composition of Algerian Pinus halepensis Mill. Essential Oils Obtained by Hydrodistillation and Solvent-Free Microwave Extraction Methods and Their Biological Activities

Chemical Composition of Algerian Pinus halepensis Mill. Essential Oils Obtained by Hydrodistillation and Solvent-Free Microwave Extraction Methods and Their Biological Activities

Extraction of essential oil from fresh basil leaves (Ocimum basilicum L.) using solvent-free microwave extraction method: Extraction parameter optimization, electric consumption, and CO2 emission study

Essential oil extraction is often still done using conventional methods. This process requires a long time, a lot of energy, and a large amount of solvent. Therefore, solvent-free microwave extraction (SFME) was chosen as a better and greener alternative. The objectives of this study were: (i) to determine the optimum conditions for basil oil extraction in the SFME method using Box-Behnken Design (BBD) and (ii) to analyze the electric consumption and CO2 emissions produced during the extraction process. The results showed that microwave power, F/D ratio, and extraction time to obtain optimum conditions were 600 W, 100 g/L, and 18.12 min, respectively. Extraction using hydro distillation (HD) method consumes 1 kWh of electricity and produces 0.80 kg of CO2 emission more than the SFME method. The yield of essential oil carried out using SFME method produces more oil than the HD method. The use of less energy and more optimal results make the extraction process with SFME greener and environmentally friendly.

COMPARISON PROCESS OF SOLVENT-FREE MICROWAVE EXTRACTION AND MICROWAVE HYDRO-DISTILLATION METHODS IN ESSENTIAL OIL PRODUCTION FROM CABBAGE ROSES FLOWER (Rose × centifolia)

Indonesia has many diverse natural resources that still cannot be utilized optimally such as the extraction of essential oil from Cabbage Roses flowers (Rose × centifolia). This study compares the extraction amendments, extraction time, and essential oil composition of fresh rose flowers obtained by the Solvent-Free Microwave Extraction (SFME) method to those obtained using the Microwave Hydro-Distillation (MHD) extraction method. Optimum conditions using the same amount of raw material in this study for the MHD method optimum conditions of operation: time of 90 minutes; the ratio of 1 g/mL; the power of 450 W, obtained a yield of 0.152% and SFME method optimum conditions of operation: time of 90 minutes, ratio 0.2 g/mL; power 450 W, obtained a yield of 0.358%. Electricity consumption to obtain 1 g of rose essential oil extracted using the MHD method is 4.087 kWh, while for the SFME method, it is 1.073 kWh. So it can also be said that the MHD method requires electricity consumption which is 3.8 times higher when compared to the SFME method.

Variation in Yield, Chemical Composition and Biological Activities of Essential Oil of Three Curcuma Species: A Comparative Evaluation of Hydrodistillation and Solvent-Free Microwave Extraction Methods.

The essential oils of three medicinally important Curcuma species (Curcuma alismatifolia, Curcuma aromatica and Curcuma xanthorrhiza) were extracted using conventional hydro-distillation (HD) and solvent free microwave extraction (SFME) methods. The volatile compounds from the rhizome essential oils were subsequently analysed by GC-MS. The isolation of essential oils of each species was carried out following the six principles of green extraction and comparison was made between their chemical composition, antioxidant, anti-tyrosinase and anticancer activities. SFME was found to be more efficient than HD in terms of energy savings, extraction time, oil yield, water consumption and waste production. Though the major compounds of essential oils of both the species were qualitatively similar, there was a significant difference in terms of quantity. The essential oils extracted through HD and SFME methods were dominated by hydrocarbon and oxygenated compounds, respectively. The essential oils of all Curcuma species exhibited strong antioxidant activity, where SFME was significantly better than HD with lower IC50 values. The anti-tyrosinase and anticancer properties of SFME-extracted oils were relatively better than that of HD. Further, among the three Curcuma species, C. alismatifolia essential oil showed the highest rates of inhibition in DPPH and ABTS assay, significantly reduced the tyrosinase activity and exhibited significant selective cytotoxicity against MCF7 and PC3 cells. The current results suggested that the SFME method, being advanced, green and fast, could be a better alternative for production of essential oils with better antioxidant, anti-tyrosinase and anticancer activities for application in food, health and cosmetic industries.

Yield, chemical composition, and antioxidant activity of essential oil obtained from Ferula persica oleo-gum-resin: Effect of the originated region, type of oleo-gum-resin, and extraction method

In the present study, we investigated the effect of extraction methods (hydro-distillation, microwave-assisted hydro-distillation, and solvent-free microwave extraction), oleo-gum-resin types (Kokh and Shir), and regions (Sepidan and Darb-e-Behesht) on yield, composition and antioxidant activity of essential oils obtained from oleo-gum-resin of Ferula persica. The results showed that oleo-gum-resins originating from Darb-e-Behesht produced more essential oil than oleo-gum-resins of Sepidan using each of the extraction methods. Each of the extraction methods isolated more essential oil from Kokh samples as compared with Shir. The highest essential oil was achieved by the solvent-free microwave extraction method from Kokh samples. A total of 51 compounds were identified in essential oil samples. Monoterpene hydrocarbons and sulfur compounds were dominant in all essential oils. The main compounds of essential oil in the samples were β-pinene, α-pinene, (E)− 1-Propenyl sec-butyl disulfide, and (Z)− 1-Propenyl sec-butyl disulfide. The antioxidant activity of the essential oils was affected by the region and type of oleo-gum-resin. The essential oils showed less antioxidant activity than butylated hydroxyanisole. The research suggests that the area of oleo-gum-resin collection, type of oleo-gum-resin collected, and essential oil extraction method should be selected and optimized based on the intended purpose and the desired active ingredients. Also, the results show that microwave-assisted hydro-distillation and solvent-free microwave extraction methods can be introduced as quick and suitable alternative methods for extracting essential oils from oleo-gum-resins of F.persica.

Solvent-Free Microwave Extraction of Essential Oils from Litsea cubeba (Lour.) Pers. at Different Harvesting Times and Their Skin-Whitening Cosmetic Potential.

Litsea cubeba fruit, which has the highest content of essential oils in the plant, is an important woody oil plant resource. In this study, the influence of the solvent-free microwave extraction (SFME) and hydrodistillation (HD) techniques on the extraction of L. cubeba fruit essential oils was investigated in terms of yield, kinetics, and chemical composition, where the former conditions were optimized by the response surface design. The maximal essential oil yield was obtained under the optimal SFME process conditions (442 W and 24 min), where the irradiation time was the most important variable (p < 0.0001). Regardless of the extraction method used, the influence of harvesting time on L. cubeba fruit essential oils were quantitatively and qualitatively analyzed afterwards, where the SFME essential oil from July showed its superiority over the others regarding its higher extraction yield and better bioactivities. Compared with the HD method, the SFME approach could significantly enhance the yield of essential oils extracted from June to August by nearly 47% with the advantages of saving energy and low environmental impact. Interestingly, the SFME method could selectively extract monoterpene hydrocarbons such as D-limonene with relation to different compositions and bioactivities. Moreover, SFME essential oil showed a better inhibitory effect on tyrosinase and melanogenesis, indicating its skin-whitening potential as a new promising natural cosmetic ingredient.

Optimization of Essential Oil Extraction of Beluntas (Pluchea Indica L.) Leaves by Using Solvent-Free Microwave Extraction

Beluntas (Pluchea Indica L.) which commonly used as astringent and antipyretic has a high potential for the feedstock of essential oil production. The objective of this work is to optimize solvent-free microwave extraction (SFME) of Beluntas leaves by using response surface methodology (RSM). Box-Behnken Design with the variations of extraction time (60-120 min), feed/distiller ratio (0.06-0.1 g/ml), and heating power (150-450 W) was utilized to optimize essential oil yield. The feed/distiller ratio factor had the highest significant effect on the essential oil yield (P<0.05). Essential oil yield increased as the increase of oil heating power and time extraction, and vice versa. On the other hand, the increase in the feed/distiller ratio gave a negative impact on the essential oil yield. The maximum essential oil yield using SFME method of 0.2728 b/b% was obtained for the optimized condition of extraction time of 90 min, microwave heating power of 450 W, and feed/distiller ratio of 0.06.

Essential oil extraction and evaluation from the fresh Platycladus orientalis (L.) Franco seed peel waste by an environment-friendly method

In this study, the essential oil was extracted and characterized from fresh seed peel waste of Platycladus orientalis (L.) Franco by enzymatic pretreatment combined with solvent-free microwave extraction method (EP-SME) for the first time. The optimal preparation conditions were obtained by single-factor and response surface optimization. Under the optimum conditions, the essential oil yield was 1.13%, which was 24.18% higher than that by traditional steam distillation method (SD) (0.91%), and the essential oil was rich in more polyphenols and flavonoids. The results of gas chromatography-mass spectrometry showed that the essential oil from EP-SME method had the high percentage of oxygenated compound (13.38%). Compared with SD method, the content increments of the first three components were cedrol (+4.91%), 2-carene (+2.31%), caryophyllene (+0.81%), respectively. In addition, the essential oil from the EP-SFME method showed higher comprehensive antioxidant activity and stronger acetylcholinesterase inhibitory activity than those from the hydrodistillation method. The results of extraction kinetics and energy consumption showed that EP-SME method had high extraction efficiency and reached the extraction equilibrium point in a short time (50 min). Its energy consumption and gas emission were only 15.16% of SD.

Comparison of chemical composition and activities of essential oils from fresh leaves of Pelargonium graveolens L′Herit. extracted by hydrodistillation and enzymatic pretreatment combined with a solvent-free microwave extraction method

In this study, enzymatic pretreatment combined with solvent-free microwave extraction (EP-SFME) was used to extract essential oils from fresh leaves of Pelargonium graveolens L′Herit. The effects of hydrodistillation and enzymatic pretreatment combined with solvent-free microwave extraction on the yield and quality of essential oils were compared. The essential oil yield from the EP-SFME method (0.29% ± 0.04%) was 26.09% higher than that from the conventional hydrodistillation method. The gas chromatography-mass spectrometry analysis results showed that the content of main components in the essential oil from the EP-SFME method was significantly increased, including citronellol (+8.60%), geraniol (+3.14%), citronellyl formate (+2.77%), and geranic acid (+1.54%). The content of oxygenated compounds was also far higher than that of the hydrodistillation method. The essential oil from the EP-SFME method showed stronger antidepressant potential, as determined by the inhibition rate of acetylcholinesterase (IC50 =73.3 µg/mL). In contrast, the essential oil from the EP-SFME method showed higher comprehensive antimicrobial activity, including Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii, and Candida albicans, and antioxidant activity than that from the hydrodistillation method. Therefore, the EP-SFME method is a green and effective method for the extraction of high-quality essential oils from fresh leaves of Pelargonium graveolens L′Herit.

One-pot extraction and enrichment of diallyl trisulfide in garlic oil using an eco-friendly solvent-free microwave extraction method

The H2S-releasing donor capabilities of garlic polysulfanes, particularly diallyl trisulfide, have been shown to exhibit cardioprotective, antiatherosclerotic, and anticarcinogenic effects. These properties lead to the ubiquitous use of garlic oil in pharmaceuticals; nevertheless, there is a lack of a simple, optimal, and environmentally friendly approach for increasing diallyl trisulfide levels. This study aimed to establish a one-pot extraction and enrichment method for diallyl trisulfide in garlic oil using solvent-free microwave extraction (SFME). In the SFME processes, a face-centered central composite design (FCCCD) was applied by treating the moisture content, microwave power, and irradiation time as independent factors, whereas the response was volatile oil yield. The extraction method was optimized using response surface methodology and Derringer’s desirability function. Under optimal conditions, SFME was implemented to assure the maximum qualitative and quantitative quality of garlic oils collected from different origins. The volatile oils obtained were analyzed by gas chromatography−mass spectrometry. The optimum conditions for SFME were a 68% moisture content and irradiation at 640 W for 20 min, yielding 0.30 ± 0.02% w/w garlic oil. The proposed SFME conditions were more efficient than hydrodistillation (HD) in production yields and the proportion of diallyl trisulfides. When the proposed conditions were implemented, garlic oil yields varied between 0.14% w/w and 0.32% w/w, with a high proportion of the target diallyl trisulfide. This finding highlights an appropriate model for extracting diallyl trisulfide-rich garlic oil using an eco-friendly technology that is more efficient than the conventional HD method.

Chemical profile and antimicrobial activity of essential oil and methanol extract from peels of four Durio zibethinus L. varieties

Durio zibethinus L. (durian) belongs to the Malvaceae family. It is known as the “King of Tropical Fruit” because of its unique characteristics. The edible part of durian, however, is only about 33% of the fruit while the non-edible parts such as the seed and peels (rinds) are considered as fruit waste responsible for environmental pollution. Thus, the present study was carried out to compare the percentage yields and volatile components from methanol extract and essential oils of the peels of four varieties of durian (Raja Kunyit [D197], Hajah Hasmah [D168], Sultan [D24], and Golden Bun [D13]). The antimicrobial activity of all the extracts and their volatile chemical constituents were also evaluated. Cold maceration was used for the solvent (methanol) extraction. The essential oil extraction was carried out using hydro-distillation and solvent-free microwave extraction (SFME) methods. The antimicrobial activity was evaluated against selected microbes using the well diffusion method while the characterization of chemical constituents in the essential oils and crude methanolic extracts was carried out using gas chromatography-mass spectrometry (GC–MS). The highest yields of essential oils were obtained from D24 which were 0.030% and 0.014% from SFME and hydro-distillation extraction, respectively, while the highest and most significant (p < 0.05) yield of methanol extract (8.79%) was obtained from D197. From the GC–MS analysis, butanoic acid was the major compound in the essential oil of durian peels in the four varieties of durians evaluated. Besides butanoic acid, 1-tridecene, 1-pentadecene, and 1-heptadecene were also present in the four varieties. The D168 possesses strong activity against three bacteria (Bacillus subtilis, Staphylococcus aureus, and Pseudomonas aeruginosa). More novel extraction techniques, bioactivity assays, and characterization are, however, recommended to further explore the potential benefits of durian peels.

A comparison of essential oil extraction from the leaves of lemongrass (Cymbopogon nardus L.) using two microwave-assisted methods

The extraction of essential oils from Lemongrass leaves (Cymbopogon nardus L.) has become more promising than ever before due to the oils' increasing demand in the market in addition to the dynamic breakthrough in its technology advancement. This study presents a comparison of two different methods of microwave-assisted essential oil extraction, namely Microwave Hydrodistillation (MHD) and Solvent-Free Microwave Extraction (SFME), both of which exhibit a better quality in terms of essential oil recovery compared to the conventional extraction methods. This study investigated the effect of extraction time, microwave power, as well as feed-to-distiller volume ratio (F/D). Experimental results suggest that although there is a tendency to increase yield along with the increasing power, the yield turns out to decrease at higher power, with the optimum power for the MHD method being 420 W and that of the SFME method being 560 W. Smaller F/D ratios appear to give higher yields for both methods and the smaller the size of the material, the higher the yield obtained. The MHD method produces a smaller yield but has a better quality of citronella oil compared to the SFME method. Two first-order and second-order extraction kinetics models were compared for both the MHD and SFME methods, and the results suggest that the first-order model was slightly better at representing the experimental data based on the RMSD and R2 values. This applies to both experimental data using the MHD and SFME methods, respectively.

Solvent-Free Microwave Extraction of Thymus mastichina Essential Oil: Influence on Their Chemical Composition and on the Antioxidant and Antimicrobial Activities.

Solvent-free microwave extraction (SFME) is a combination of microwave heating and dry distillation performed at atmospheric pressure without the addition of water or organic solvents that has been proposed as a green method for the extraction of essential oils from aromatic and medicinal herbs. In this work, SFME and the conventional techniques of steam distillation (SD) and hydrodistillation (HD) were compared with respect to the extraction and antioxidant and antimicrobial activities of Thymus mastichina essential oil. The main constituent of essential oils obtained using different methods was 1,8-cineole (eucalyptol). The results showed that the essential oils extracted by means of SFME in 30 min were quantitatively (yield) and qualitatively (aromatic profile) similar to those obtained using conventional HD over 120 min. In addition, SFME generates less waste and less solvent, consumes less energy, and provides a higher yield for a shorter extraction time, which is advantageous for the extraction of the T. mastichina essential oil compared to SD. The antioxidant and antimicrobial activities of the T. mastichina essential oil obtained from either SFME or conventional extraction methods (SD or HD) showed a similar pattern. Large-scale experiments using this SFME procedure showed a potential industrial application.

Increasing the essential oil yield from Shorea roxburghii inflorescences using an eco-friendly solvent-free microwave extraction method for fragrance applications

The short bloom period of Shorea roxburghii G.Don is a technical challenge in the development of a fast and efficient process for recovering essential oils. This study aimed to optimize the conditions for the isolation of essential oil and the determination of the resulting oil's possible bioactivities for fragrance applications. Solvent-free microwave extraction (SFME) coupled with response surface methodology (RSM) was applied to study essential oil from fresh inflorescences. The microwave power and irradiation time were chosen as crucial independent variables, while essential oil yield was the response variable. The physicochemical, antioxidant, olfactory, cytotoxic, and irritant properties of the resulting oil were evaluated. SFME yielded essential oil with a unique and pleasant scent, similar to that of fresh flowers. Increased microwave power and irradiation time increased the oil yield. The proportions of oxygenated compounds with high antioxidant properties were notably higher after SFME than after hydrodistillation. The optimal conditions for maximizing the oil yield were 800 W and 35 min. Among 51 volatile substances, germacrene B, kaur-16-ene, β-caryophyllene, and (E)-linalool oxide (furanoid) were the oil's main components. Low toxicity to primary human dermal fibroblast cells was defined at an oil concentration < 50 μg/mL. Moreover, the application of the extracted volatile oil to hen’s egg-chorioallantoic membrane resulted in a low degree of irritation. This research establishes optimal extraction conditions for the isolation of essential oil with potential for fragrance applications.

Chemical Composition of Essential Oils Obtained from Heteromorpha arborescens (Spreng.) Cham. and Schltdl Leaves Using Two Extraction Methods.

This study was aimed at comparing the essential oils obtained from Heteromorpha arborescens leaves by Solvent-Free Microwave Extraction (SFME) and Hydrodistillation (HD) methods in terms of their chemical compositions, yield, CO2 emission, and energy consumption. The solvent-free microwave extraction method indicated a higher oil yield of 0.7 mL/200 g (0.35%) as compared to 0.59 mL/200 g (0.295%) obtained through hydrodistillation. GC-MS analysis of the oils revealed a total of 52 chemical components from both methods with the presence of 35 (96.52%) and 30 (71.15%) chemical constituents for HD and SFME, respectively. The major constituents observed in the essential oil extracted by SFME methods include α-pinene (6%), D-limonene (11.27%), β-ocimene (9.09%), β-phellandrene (6.33%), β-mycene (8.49%), caryophyllene (5.96%), and camphene (4.28%). However, in the hydrodistillation method, the oil was majorly composed of a-pinene (4.41%), β-pinene (10.68%), β-ocimene (6.30%), germacrene-D (5.09%), humulene (5.55%), and α-elemene (6.18%). The SFME method was better in terms of saving energy (0.25 kWh against 4.2 kWh of energy consumed), reduced CO2 emission (200 g against 3360 g of CO2), a higher yield, and better quality of essential oil due to the presence of higher valuable oxygenated compounds (8.52%) against that of the hydrodistillation method (2.96%). The SFME method is, therefore, a good alternative for extracting the oils of H. arborescens leaves since the essential oil yield is higher with more oxygenated compounds, considerable energy savings, lower cost, and reduced environmental burden at substantially reduced extraction time (30 min as opposed to 180 min).

The Extraction of Essential Oil from Piper Cubeba by Using Solvent Free Microwave Extraction Method

This research aims to study the production of essential oil from Piper Cubeba using the solvent-free microwave extraction (SFME) method. Before extraction, the raw materials are prepared in the form of grains and powders to vary the size of the raw materials. Time variation was carried out at microwave power 180 Watt Analyses were then performed on the resulting essential oil using both physical and chemical tests of density and solubility with 96% alcohol. Analyses of chemical compounds within the essential oil were then performed using the Gas Chromatograph Mass Spectrometry (GC-MS). It was found that the production of essential oil from Piper Cubeba using the SFME method was affected by microwave power, grain size, and treatment duration. Results from physical and chemical analyses revealed that the resulting cubeb oil has 0.86 g/mL density, which means that essential oil produced using the SFME method is lighter compared than those produced using MAHD methods. Results from GC-MS analyses showed eight components detected from the production of essential oil from Piper cubeba using the SFMEmethod; Copaene (39.28%), Cubebene (23.83%), Isoledene (11.66%), Naphthalene (6.65%), Phellandrene (5.81%), Asarone (5.71%), Cadidene (4.90%), and Caryophyllene (2.16%) which contents belong to the sesquiterpene group

Antioxidant, cytotoxic and antibacterial activity of Rosmarinus officinalis L. essential oil against bacteria isolated from urinary tract infection

IntroductionUrinary tract infection (UTI) is a common infection in humans. The main disadvantage of antibiotic usage for UTI treatment is the emergence of antibiotic-resistant bacteria, which endanger antibiotic efficacy. The essential oil of some plants have antimicrobial activity without enhancing the antibiotic resistance. MethodsIn this study, Rosmarinus officinalis L. from Marivan (Kurdistan Province, Iran) was selected, and essential oil was prepared using a solvent-free microwave extraction method. The essential oil components were evaluated by Gas Chromatography-Mass Spectrometry. The agar diffusion and broth microdilution methods were used to investigate essential oil antibacterial effects against standard reference strains and clinical microbial strains isolated from UTI samples of Al-Zahra hospital in Najaf, Iraq. The antioxidant and cytotoxic activity of the oil was also examined by the β-carotene bleaching assay and brine shrimp lethality test, respectively. ResultsThe main components of the essential oil were 1,8-cineole (17.16 %) and α-pinene (16.95 %). The essential oil showed antibacterial activity against all the tested strains, with inhibition zones and minimum inhibitory concentrations (MIC) in the range of 7.00 ± 0.00–9.6 ± 0.32 mm and 0.06 ± 0.00 to 0.16 ± 0.07 mg/mL, respectively. The minimum bactericidal concentration (MBC) values were equal to MIC values. The greatest microbial inhibitory effect was against Staphylococcus aureus, Klebsiella pneumoniae, and Proteus vulgaris, respectively. Furthermore, the oil indicated good antioxidant capacity and high cytotoxicity. ConclusionThis study demonstrated that R. officinalis L. essential oil from Marivan has noteworthy antibacterial activity and can be useful for the treatment of UTI.

MICROWAVE ASSISTED-EXTRACTION OF ESSENTIAL OIL FROM FRESH BASIL (OCIMUM BASILICUM L.) LEAVES

In this research, the extraction of essential oil from fresh basil leaves using solvent-free microwave extraction (SFME)and microwave hydrodistillation (MHD) method. Several parameters influence the extraction of basil oil using SFME method: microwave power, the ratio between the mass of raw material with a volume of distiller (F/D), material size, and length of extraction time. Besides, the components contained in basil oil and changes in oil gland conditions in basil leaves before and after being extracted were also evaluated. The optimum condition was obtained as follows: microwave power of 380 W, the ratio between the mass of raw material with a volume of distiller (F/D) of 0.1 g/mL,  raw material size of intact (± 3 cm), with an extraction time of 60 min. Moreover, SFME has a shorter extraction time to produce yields than MHD methods. GC-MS analyzed the composition of basil oil, and there were 49 identified components. This study shows that SFME method more effective than the MHD method for extraction basil oil from fresh leaves based on time extraction and yield.

Volatile Components of Haplophyllum canaliculatum Boiss. by Different Extraction Procedures.

Volatile components of Haplophyllum canaliculatum Boiss. grown in Iran were extracted by hydrodistillation (HD), solvent-free microwave extraction (SFME), and headspace solid-phase microextraction (HS-SPME). The components were analyzed by means of GC and GC-MS. The extraction time and temperature for HS-SPME, microwave, power, and exposure time of extraction for SFME were optimized. Twenty-five compounds that represent 99.88% of total compounds in the oil were obtained by the HD method, and the major components for this method were identified as β-pinene (18.90%), 1,8-cineole (13.94%), and piperitone (12.22%). However, piperitone (34.50%), caryophyllene oxide (9.94%), and a-eudesmol were the main compounds among twenty-one constituents, representing 99.89% of the total composition that were characterized in volatiles extracted by the SFME method. Moreover, thirteen compounds, representing 99.95% of the total constituents, were characterized in volatile fraction extracted by the HS-SPME method, which were dominated by β-pinene (21.13%), a-pinene (13.07%), limonene (11.65%), and δ-2-carene (10.23%) as major constituents.

Optimization of solvent-free microwave extraction of Centella asiatica using Taguchi method

Centella asiatica (C. asiatica) is a common herb found in the Indian subcontinent, Southeast Asia, and wetland regions of the Southern US. Although it grows abundantly in these regions, very few reports are available on the modern extraction of C. asiatica, especially by the solvent-free microwave extraction (SFME) method. In this study, the process parameters (microwave power, extraction time, vacuum and stirrer) affecting SFME of asiaticoside from C. asiatica were optimized by the Taguchi method. Here, the vacuum was identified as the primary factor that contributes to the level of yield followed by microwave power, extraction time and stirrer. The highest amount of asiaticoside detected in the C. asiatica extract was 158.8 μg ml−1. The extraction carried out at optimized conditions for the confirmatory study was found to produce 0.38 % of more extract yield than the highest yield obtained in the test runs of Taguchi design, thereby supporting the accuracy of optimization of process parameters under the given set of experimental conditions.