Now showing1 - 3 of 3
- Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Extraction of caffeine, theobromine, and cocoa butter from Brazilian cocoa beans using supercritical CO2 and ethane(American Chemical Society (ACS), 2002-11-19); ; ; ; Supercritical extraction using ethane and CO2, acceptable solvents for food products, was explored for the recovery of the methylxanthines caffeine and theobromine and cocoa butter from cocoa beans using a high-pressure apparatus. Continuous extraction of cocoa beans was performed at 343.2 K using CO2 at pressures of 20 and 40 MPa and ethane at pressures of 15.2, 24.8, and 28.3 MPa. The extraction yields of cocoa butter obtained with ethane were much higher than those obtained with CO2 because of the higher solubility of this fat in ethane. A pronounced effect of pressure on the extraction of methylxanthines and cocoa butter was observed for both solvents. Extraction curves revealed the greater facility of these solvents to extract cocoa butter followed by caffeine and theobromine. This behavior suggests a range of possible conditions under which the extraction and isolation of cocoa butter, caffeine, and theobromine from cocoa beans can be achieved. The methylxanthines in cocoa beans were slightly more soluble in ethane than in CO2 probably because of co-solvency effects of cocoa butter, which was extracted more easily using supercritical ethane. Despite the higher cost of ethane, its critical pressure is lower than that of CO2, and the higher butter solubility could render ethane a viable solvent through lower energy costs.Publicationtype: Journal Article62 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Extraction of methylxanthines from guaraná seeds, maté leaves, and cocoa beans using supercritical carbon dioxide and ethanol(American Chemical Society (ACS), 2002-07-17); ; ; New experimental data on the extraction of caffeine from guaraná seeds and maté 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 guaraná seeds and maté tea leaves were obtained. Extractions of caffeine from guaraná seeds and maté 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 addition of ethanol to carbon dioxide on the extraction of methylxanthines was significant, particularly in the extraction of theobromine from cocoa beans. In general, the use of ethanol results in lower solvent and energy requirements and thereby improved extraction efficiency.Publicationtype: Journal ArticleScopus© Citations 95 41 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Decaffeination of guaraná seeds in a microextraction column using water-saturated CO2(Elsevier, 2002-01-25); ; ; Experimental data on the reduction of the caffeine content of guaraná 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 guaraná 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 guaraná seeds was also observed at 100 bar for the 40 and 70 °C isotherms.Publicationtype: Journal Article37