The Experts below are selected from a list of 8343 Experts worldwide ranked by ideXlab platform
Gerd Brunner - One of the best experts on this subject based on the ideXlab platform.
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Extraction of methylxanthines from guarana seeds mate leaves and cocoa beans using supercritical carbon dioxide and ethanol
Journal of Agricultural and Food Chemistry, 2002Co-Authors: Marleny D.a. Saldaña, Rahoma S. Mohamed, Carsten Zetzl, Gerd BrunnerAbstract:New experimental data on the Extraction of caffeine from guarana seeds and mate tea leaves, and theobromine from cocoa beans, with supercritical CO2 were obtained using a high-pressure Extraction Apparatus. The effect of the addition of ethanol to carbon dioxide on the Extraction efficiency was also investigated. Caffeine Extraction yields of 98% of the initial caffeine content in both wet ground guarana seeds and mate tea leaves were obtained. Extractions of caffeine from guarana seeds and mate tea leaves also exhibited a retrograde behavior for the two temperatures considered in this work. In the removal of theobromine from cocoa beans, a much smaller Extraction yield was obtained with longer Extraction periods and consequently larger solvent requirements. The results of this study confirm the higher selectivity of CO2 for caffeine in comparison with that for theobromine, and also the influence of other components in each particular natural product on the Extraction of methylxanthines. The effect of the...
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Decaffeination of guaraná seeds in a microExtraction column using water-saturated CO2
The Journal of Supercritical Fluids, 2002Co-Authors: Marleny D.a. Saldaña, Rahoma S. Mohamed, Carsten Zetzl, Gerd BrunnerAbstract:Abstract Experimental data on the reduction of the caffeine content of guarana seeds with water-saturated supercritical carbon dioxide were obtained in order to provide information on the ability of supercritical fluids for the decaffeination of widely consumed caffeine-rich natural products. The Extraction was performed using a semi-continuous flow high-pressure micro-Extraction Apparatus at 40 and 70 °C and pressures of 100, 200 and 400 bar. Carbon dioxide flow rates of 5.7 and 9.4 g min−1 were used. The Extraction curves obtained showed the existence of thermodynamic solubility dependent, intermediate and diffusion controlled regions. Extraction at 400 bar and 70 °C using water-saturated supercritical carbon dioxide at a flow rate of 5.7 g min−1 allowed the removal of almost 98% of the initial caffeine content in wet ground guarana seeds, in a period of 240 min. When Extractions were performed at lower pressures or temperatures, additional time and larger amounts of carbon dioxide were necessary to achieve the same yield. Increasing carbon dioxide flow rate did not present any economic advantage unless the Extraction was limited to the thermodynamic solubility region. For total Extraction of caffeine, the use of low flow rates resulted in a similar final product yield but at a much lower solvent consumption. A retrograde behavior for the Extraction of caffeine from guarana seeds was also observed at 100 bar for the 40 and 70 °C isotherms.
Marleny D.a. Saldaña - One of the best experts on this subject based on the ideXlab platform.
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Extraction of methylxanthines from guarana seeds mate leaves and cocoa beans using supercritical carbon dioxide and ethanol
Journal of Agricultural and Food Chemistry, 2002Co-Authors: Marleny D.a. Saldaña, Rahoma S. Mohamed, Carsten Zetzl, Gerd BrunnerAbstract:New experimental data on the Extraction of caffeine from guarana seeds and mate tea leaves, and theobromine from cocoa beans, with supercritical CO2 were obtained using a high-pressure Extraction Apparatus. The effect of the addition of ethanol to carbon dioxide on the Extraction efficiency was also investigated. Caffeine Extraction yields of 98% of the initial caffeine content in both wet ground guarana seeds and mate tea leaves were obtained. Extractions of caffeine from guarana seeds and mate tea leaves also exhibited a retrograde behavior for the two temperatures considered in this work. In the removal of theobromine from cocoa beans, a much smaller Extraction yield was obtained with longer Extraction periods and consequently larger solvent requirements. The results of this study confirm the higher selectivity of CO2 for caffeine in comparison with that for theobromine, and also the influence of other components in each particular natural product on the Extraction of methylxanthines. The effect of the...
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Decaffeination of guaraná seeds in a microExtraction column using water-saturated CO2
The Journal of Supercritical Fluids, 2002Co-Authors: Marleny D.a. Saldaña, Rahoma S. Mohamed, Carsten Zetzl, Gerd BrunnerAbstract:Abstract Experimental data on the reduction of the caffeine content of guarana seeds with water-saturated supercritical carbon dioxide were obtained in order to provide information on the ability of supercritical fluids for the decaffeination of widely consumed caffeine-rich natural products. The Extraction was performed using a semi-continuous flow high-pressure micro-Extraction Apparatus at 40 and 70 °C and pressures of 100, 200 and 400 bar. Carbon dioxide flow rates of 5.7 and 9.4 g min−1 were used. The Extraction curves obtained showed the existence of thermodynamic solubility dependent, intermediate and diffusion controlled regions. Extraction at 400 bar and 70 °C using water-saturated supercritical carbon dioxide at a flow rate of 5.7 g min−1 allowed the removal of almost 98% of the initial caffeine content in wet ground guarana seeds, in a period of 240 min. When Extractions were performed at lower pressures or temperatures, additional time and larger amounts of carbon dioxide were necessary to achieve the same yield. Increasing carbon dioxide flow rate did not present any economic advantage unless the Extraction was limited to the thermodynamic solubility region. For total Extraction of caffeine, the use of low flow rates resulted in a similar final product yield but at a much lower solvent consumption. A retrograde behavior for the Extraction of caffeine from guarana seeds was also observed at 100 bar for the 40 and 70 °C isotherms.
Carsten Zetzl - One of the best experts on this subject based on the ideXlab platform.
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Extraction of methylxanthines from guarana seeds mate leaves and cocoa beans using supercritical carbon dioxide and ethanol
Journal of Agricultural and Food Chemistry, 2002Co-Authors: Marleny D.a. Saldaña, Rahoma S. Mohamed, Carsten Zetzl, Gerd BrunnerAbstract:New experimental data on the Extraction of caffeine from guarana seeds and mate tea leaves, and theobromine from cocoa beans, with supercritical CO2 were obtained using a high-pressure Extraction Apparatus. The effect of the addition of ethanol to carbon dioxide on the Extraction efficiency was also investigated. Caffeine Extraction yields of 98% of the initial caffeine content in both wet ground guarana seeds and mate tea leaves were obtained. Extractions of caffeine from guarana seeds and mate tea leaves also exhibited a retrograde behavior for the two temperatures considered in this work. In the removal of theobromine from cocoa beans, a much smaller Extraction yield was obtained with longer Extraction periods and consequently larger solvent requirements. The results of this study confirm the higher selectivity of CO2 for caffeine in comparison with that for theobromine, and also the influence of other components in each particular natural product on the Extraction of methylxanthines. The effect of the...
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Decaffeination of guaraná seeds in a microExtraction column using water-saturated CO2
The Journal of Supercritical Fluids, 2002Co-Authors: Marleny D.a. Saldaña, Rahoma S. Mohamed, Carsten Zetzl, Gerd BrunnerAbstract:Abstract Experimental data on the reduction of the caffeine content of guarana seeds with water-saturated supercritical carbon dioxide were obtained in order to provide information on the ability of supercritical fluids for the decaffeination of widely consumed caffeine-rich natural products. The Extraction was performed using a semi-continuous flow high-pressure micro-Extraction Apparatus at 40 and 70 °C and pressures of 100, 200 and 400 bar. Carbon dioxide flow rates of 5.7 and 9.4 g min−1 were used. The Extraction curves obtained showed the existence of thermodynamic solubility dependent, intermediate and diffusion controlled regions. Extraction at 400 bar and 70 °C using water-saturated supercritical carbon dioxide at a flow rate of 5.7 g min−1 allowed the removal of almost 98% of the initial caffeine content in wet ground guarana seeds, in a period of 240 min. When Extractions were performed at lower pressures or temperatures, additional time and larger amounts of carbon dioxide were necessary to achieve the same yield. Increasing carbon dioxide flow rate did not present any economic advantage unless the Extraction was limited to the thermodynamic solubility region. For total Extraction of caffeine, the use of low flow rates resulted in a similar final product yield but at a much lower solvent consumption. A retrograde behavior for the Extraction of caffeine from guarana seeds was also observed at 100 bar for the 40 and 70 °C isotherms.
Rahoma S. Mohamed - One of the best experts on this subject based on the ideXlab platform.
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Extraction of methylxanthines from guarana seeds mate leaves and cocoa beans using supercritical carbon dioxide and ethanol
Journal of Agricultural and Food Chemistry, 2002Co-Authors: Marleny D.a. Saldaña, Rahoma S. Mohamed, Carsten Zetzl, Gerd BrunnerAbstract:New experimental data on the Extraction of caffeine from guarana seeds and mate tea leaves, and theobromine from cocoa beans, with supercritical CO2 were obtained using a high-pressure Extraction Apparatus. The effect of the addition of ethanol to carbon dioxide on the Extraction efficiency was also investigated. Caffeine Extraction yields of 98% of the initial caffeine content in both wet ground guarana seeds and mate tea leaves were obtained. Extractions of caffeine from guarana seeds and mate tea leaves also exhibited a retrograde behavior for the two temperatures considered in this work. In the removal of theobromine from cocoa beans, a much smaller Extraction yield was obtained with longer Extraction periods and consequently larger solvent requirements. The results of this study confirm the higher selectivity of CO2 for caffeine in comparison with that for theobromine, and also the influence of other components in each particular natural product on the Extraction of methylxanthines. The effect of the...
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Decaffeination of guaraná seeds in a microExtraction column using water-saturated CO2
The Journal of Supercritical Fluids, 2002Co-Authors: Marleny D.a. Saldaña, Rahoma S. Mohamed, Carsten Zetzl, Gerd BrunnerAbstract:Abstract Experimental data on the reduction of the caffeine content of guarana seeds with water-saturated supercritical carbon dioxide were obtained in order to provide information on the ability of supercritical fluids for the decaffeination of widely consumed caffeine-rich natural products. The Extraction was performed using a semi-continuous flow high-pressure micro-Extraction Apparatus at 40 and 70 °C and pressures of 100, 200 and 400 bar. Carbon dioxide flow rates of 5.7 and 9.4 g min−1 were used. The Extraction curves obtained showed the existence of thermodynamic solubility dependent, intermediate and diffusion controlled regions. Extraction at 400 bar and 70 °C using water-saturated supercritical carbon dioxide at a flow rate of 5.7 g min−1 allowed the removal of almost 98% of the initial caffeine content in wet ground guarana seeds, in a period of 240 min. When Extractions were performed at lower pressures or temperatures, additional time and larger amounts of carbon dioxide were necessary to achieve the same yield. Increasing carbon dioxide flow rate did not present any economic advantage unless the Extraction was limited to the thermodynamic solubility region. For total Extraction of caffeine, the use of low flow rates resulted in a similar final product yield but at a much lower solvent consumption. A retrograde behavior for the Extraction of caffeine from guarana seeds was also observed at 100 bar for the 40 and 70 °C isotherms.
Charngcherng Chyau - One of the best experts on this subject based on the ideXlab platform.
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composition and antioxidant activity of the essential oil from curcuma zedoaria
Food Chemistry, 2003Co-Authors: Naiphon Wang, Chienchou Chen, Chihuarng Chang, Charngcherng ChyauAbstract:Abstract Curcuma zedoaria (Berg.) Rosc. (Zingiberaceae) has long been used as a folk medicine. The essential oil of its dried rhizome was isolated using simultaneous steam-distillation and solvent-Extraction Apparatus and its fractions were prepared by silica gel column chromatography. Totally, 36 compounds were identified in the essential oil, including 17 terpenes, 13 alcohols and 6 ketones. The yields of Fractions 2 and 3 were 83.66 and 10.71%, respectively. Epicurzerenone and curzerene were found in the first and second highest amounts (24.1 and 10.4%). At 20 mg ml −1 , the essential oil of C. zedoaria was moderate to good in antioxidant activities by three different methods, good in reducing power and excellent in scavenging effect on 1,1-diphenyl-2-picrylhydrazyl radical but low in chelating effect on ferrous ion. However, after fractionation, with regard to all antioxidant properties assayed, fraction 4 showed consistently better effects than the essential oil did. The compound in fraction 4 responsible for better antioxidant properties might be 5-isopropylidene-3,8-dimethyl-1(5H)-azulenone.
