High-pressure solubility data of system ethanol (1) plus catechin (2) plus CO2 (3)

Supercritical fluid extraction posses several advantages over traditional liquid-solvent-based extraction methods including improved selectivity, expeditiousness, automation and environmental safety. Fluid phase equilibrium data is essential for study the viability of supercritical extraction and the design of the extraction columns often used for this type of separations. During the past few years it has been demonstrated that phenolic compounds, such catechins and procyanidins from seeds, contribute to both the flavour properties and the pharmacological effects of wine. The extraction of catechin using supercritical CO2 is not possible, it only extracts traces of product, probably due to its polar nature. So, it is necessary the use of a cosolvent. Ethanol is appropriate because it is a polar solvent permitted in food industry. This work uses different mixtures ethanol-CO2, ranging 5-30% the ethanol contained, to optimise the amount of catechin extracted. The solubility of catechin in their supercritical solvent was measured at 313 K and pressures ranging 80-120 bar. In order to correlate the obtained results, two equations of state (EOS) were successfully used (Peng-Robinson (PR) and Soave-Redlich-Kwong (SRK)). Generally both equations show similar deviations, but PR shows the better correlation with experimental data. The solubility of catechin shows an increase with the value of percentage of ethanol. The solubility rises with pressure. The extraction pressure will be limited by security cautions and, just such ethanol percentage, by operational costs. (C) 2001 Elsevier Science B.V. All rights reserved.