• Food Science and Preservation
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• v.9 no.4
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• pp.385-390
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• 2002

Functional activities of Lyophyllum ulmarium microwave-assisted extracts under different conditions including electron donating ability, tyrosinase inhibition activity and nitrite scavenging effect were examined. Total polyphenol content increased as increasing microwave power up to 90 W in the water extracts. Electron donating ability increased with microwave power up to 90 W in 50% ethanol extract and 99% ethanol extract. Tyrosinase inhibition activity and nitrite scavenging effect in the extract increased as microwave power increased during extraction. Total polyphenol content increased as extending extraction time up to 5 min in the water extract. But the highest electron donating ability and tyrosinase inhibition activity was obtained after 10 min extraction. Significantly higher total polyphenol content and electron donating ability were found in the water extract whereas greater tyrosinase inhibition activity and nitrite scavenging effect were observed in 99% ethanol extract. The maxium nitrite scavenging effect was found at pH 1.2 and decreased as pH increased.

• Food Science and Preservation
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• v.9 no.3
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• pp.332-337
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• 2002

This study was undertaken in order to compare reflux extraction(RE) and microwave-assisted extraction(MAE) in extraction efficiency and establish optimum microwave extraction conditions in obtaining Ligularia fischeri extracts. A considerable reduction in extraction time was accomplished by MAE. When 70% methanol 50% methanol 70% ethanol, or 50% ethanol was used, MAE extract contained equal levels of soluble solid and total polyphenol as obtained by RE. The optimum microwave-assisted extraction conditions for Ligularia fischeri were achieved by 120∼150 watts of microwave energy and 4∼8 minutes of extraction time. No significant changes were found in antioxidant activity with DPPH scavenging method over the variation of microwave energy or extraction time. The use of diluted methanol or ethanol improved soluble solid content(30%), total polyphenol content(2.7%) and antioxidant activity(68%).

• Korean Journal of Food Science and Technology
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• v.34 no.6
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• pp.1013-1017
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• 2002

Functional activities of Flammulina velutipes extract including electron donating ability, nitrite-scavenging effect, and tyrosinase inhibition activity was examined. Extraction were carried out by microwave-assisted extraction (MAE) under different conditions including solvent and microwave power. Tyrosinase inhibition activity and nitrite-scavenging effect increased as microwave power increased during extraction. Total phenol content and electron-donating ability reached maximum at the microwave power of 90 W. Total polyphenol content and electron-donating ability increased as extraction time extended up to 15 min, with the highest tyrosinase inhibition obtained after 5 min extraction. Significantly higher tyrosinase inhibition activity was found in 99% ethanol extract, whereas greater nitrite-scavenging effect was observed in the water extract. The maximum nitrite-scavenging effect was found at pH 1.2 and decreased as pH increased.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.3
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• pp.586-592
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• 1999

Microwave assisted extraction(MAE) is known as a more environmental friendly process with economic advantages in terms of less time, less solvent, less energy and less wastes than the current time consuming reflux method. It was applied to develop a rapid extraction method for soluble ginseng components that are major materials used for the processing of ginseng products. In a comparative study between pre established MAE(ethanol 60%, power 80 W, process time 4 min$\times$5) and current extraction method(ethanol 80%, temp. 85oC, time 8 hr$\times$5), MAE was more efficient than the current method to obtain an extract yield(soluble solid), but it was insufficient to extract individual ginsenosides, total phenols, reducing components and acidic polysaccharides. MAE with 80% ethanol by 5 times showed, however, that its extraction efficiency on soluble solid, crude saponin, major ginsenosides, and the other components was equal or superior to that of the current method, indicating that ethanol concentration is one of the critical parameters influencing the MAE process. The quality of ginseng extracts from MAE was assured by evaluating the corresponding standards and by comparing TLC and HPLC patterns with the control.

• Food Science and Preservation
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• v.15 no.1
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• pp.133-138
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• 2008

This study investigated the antioxidant activities of extracts from Angelica dahurica roots after microwave-assisted extraction with different levels of energy (120, 240W) and extraction time (5, 10, 15 and 30 min). The highest extraction yield was 11.77 mg% in water at 240W for 30 min followed by 11.42 mg% in water at 120Wand 30 min. The highest total polyphenol contents was 32.36 mg/g in an ethanol extract, followed by 31.77mg/g in water extract at the same conditions of 240W, 30 min. The electron donating abilities both the ethanol extract obtained using 240W and 30 min and the water extract obtained employing 120W and 5min showed the highest values, 83.55% and 82.49% respectively at a concentration 1.0mg/mL. The highest superoxide dismutase (SOD)-like activity was 14.16% in ethanol extract at 120Wand 15min, followed by 13.22% in the water extract at 120W and 5 min. The best extraction yield and polyphenol content after microwave-assisted extraction were achieved with 240W and 30 min using water. The best condition for extraction of electron donating ability and SOD-like activity from A dahurica roots were 120W and 5 minutes using water.

• Journal of Environmental Science International
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• v.12 no.4
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• pp.447-459
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• 2003

This study was carried out to develop an efficient process far the elimination of phenol pollutant from soils. An microwave-assisted process (MAP) and a conventional Soxhlet extraction method (SEM) were employed to extract phenol from two types of soils. The effects of extraction methods, aged time of the spiked soil samples, extraction solvent and extraction time on the extraction performance were compared. Our results demonstrate that the recoveries from standard soil spiked were at least 10% higher fer MAP than these f3r the conventional Soxhlet. The extraction time by MAP requires significantly shelter time (1 min) than 15 h of the conventional Soxhlet. The recoveries from non-contaminated soil spiked with phenol were also almost identical f3r above results. The reduction of the extraction times with efficiency higher than that afforded by the conventional Soxhlet technique supports the suitability of the MAP method.

• Natural Product Sciences
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• v.23 no.2
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• pp.75-83
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• 2017

The optimization and microwave assisted extraction of stem bark of Terminalia arjuna, quantitative estimation of the marker compounds arjunic acid and arjunolic acid using HPTLC and the evaluation of free radical scavenging activity has been performed in this study. The central composite design was used for optimization and the values of parameters for optimized batch of microwave assisted extraction were 1000 W (Power), 3 minutes (Time) and 1/120 (Solid/solvent ratio). The solvent system to carry out the HPTLC was toluene: acetic acid: ethyl acetate (5: 5: 0.5) and quantitative estimation was done using standard equations obtained from the marker compounds. The in-vitro free radical scavenging activity was performed spectrophotometrically using ascorbic acid as standard. The value of estimated percentage yield of arjunic acid and arjunolic acid was 1.42% and 1.52% which upon experimentation was obtained as 1.38% and 1.51% respectively. The DPPH assay of the different batches of microwave assisted extraction and marker compounds taken suggested that the marker compounds arjunic acid and the arjunolic acid were responsible for the free radical scavenging activity as the batch having the maximum percentage yield of the marker compounds showed best free radical scavenging effect as compared to standard ascorbic acid. The $IC_{50}$ value of the optimized batch was found to be 24.72 while that of the standard ascorbic acid was 29.83. Hence, the yield of arjunic acid and arjunolic acid has direct correlation with the free radical scavenging activity of stem bark extract of Terminalia arjuna and have potential to serve as active lead compounds for free radical scavenging activity.

• Analytical Science and Technology
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• v.16 no.2
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• pp.134-142
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• 2003

Comparison of a microwave-assisted extraction with sonication extraction was performed for arsenic speciation in fish tissue with chromatographic separation and inductively coupled plasma mass spectrometry detection. The detection limits of arsenicals with ultrasonic nebulizerand cross-flow nebulizer were shown to be similar. The arsenicals investigated were arsenobetaine (AsB), arsenite [As(III)], dimethylarsine acid (DMA), monomethylarsonic acid (MMA), arsenate [As(v)], and phenylarsonic acid (PAA). Quantitative extraction of arsenicals from dogfish muscle, DORM-2, standard reference material of NRCC (National Research Council of Canada) was achieved using 50% (v/v) methanol-water in both extraction methods. Extraction efficiency of arsenobetaine in both methods is greater than 82% with RSDs on replicates of less than 5%. The concentrations of AsB determined in extract of microwave assisted extraction and sonication methods were $14.18{\pm}0.42mg\;kg^{-1}$ and $13.54 {\pm}0.84mg\;kg^{-1}$, respectively. And the concentrations of DMA were $0.45{\pm}0.06mg\;kg^{-1}$ and $0.44{\pm}0.06mg\;kg^{-1}$, respectively.

• Bulletin of the Korean Chemical Society
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• v.30 no.11
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• pp.2687-2690
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• 2009

Due to the importance of isoflavone content in soybean extracts, the microwave-assisted process (MAP) was compared to the conventional extraction methods. For comparison of the three methods, all extraction parameters (solvent, sample to solvent ratio, temperature, etc.) were kept the same; the microwave extractor was operated at 187.5 W with an emission frequency of 2450 MHz under atmospheric pressure conditions and the extractions were carried out at 75 ${^{\circ}C}$ for 3 min while the conventional reflux was at 75 ${^{\circ}C}$ for 3 h. Total yield and crude isoflavone content were determined by ultraviolet spectrophotometric and compared with the three methods. Results indicated that the MAP was comparable to the conventional method in its capability to extract target compounds without causing any degradation; in addition it dramatically reduced the extraction time from 3 h to a few minutes, suggesting that it can be an alternative technique to the time-consuming conventional reflux method.

• Korean Journal of Plant Resources
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• v.32 no.6
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• pp.723-729
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• 2019

Fagopyrum esculentum (Buckwheat) is a globally used alternative crop that contains several useful substances with various effects; however, many of these substances (rutin, quercetin, etc.) are water insoluble. To extract these substances, alcohols is required, which is inconvenient because these solvents cause diverse problems. Many studies are underway to achieve effective extraction of these substances with water. Among of these studies, microwave assisted water extraction (MAE) has been performed extensively. In this study, we performed the extraction in various solvents and/or microwave from Fagopyrum esculentum. The analysis of the content of useful substances and the bioactivity were performed and shown to increase in MAE. Liquid chromatography-mass was performed in order to identify of the useful water-insoluble substances. Catechin, quercetin, and rutin, which are all insoluble in water, were hardly extracted with water even on heating (4.4 ppb, 3.9 ppb and 60.3 ppb, respectively). However, MAE was found to extract much more of these substances than water (1204 ppb, 110.8 ppb and 2946 ppb, respectively). Although less efficient than alcohols, MAE showed much higher efficiency than simple water extraction. These results indicate that water extraction using microwave technology is effective in cases where it is difficult to extract useful substances using water.