J. of Supercritical Fluids 31 (2004) 9–25 Prediction of the solubility of aromatic components of wine in carbon dioxide Marta Vázquez da Silva, Domingos Barbosa ∗ Departamento de Engenharia Qu´ ımica, Faculdade de Engenharia da Universidade do Porto, Pólo FEUP do Centro de Biotecnologia e Qu´ ımica Fina, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal Received 11 March 2003; received in revised form 10 September 2003; accepted 30 September 2003 Abstract The possibility of using group contribution methods to predict the solubility of the most important families of aromatic compounds of wine—alcohols, esters and aldehydes—in carbon dioxide (CO 2 ) is analyzed in this work by comparing the results obtained with three different predictive methods, which couple equations of state and mixing rules based on the concept of the excess Gibbs free energy. The methods studied are the Predictive Soave–Redlich–Kwong (PSRK), the Linear Combination of the Vidal and Michelsen mixing rules (LCVM) and the Wong–Sandler mixing rule (WS). In all these models the excess Gibbs free energy is calculated by the UNIFAC method. For the WS mixing rule, interaction parameters between the groups CO 2 /CH 2 , CO 2 /OH, CO 2 /CCOO and CO 2 /CHO are obtained. For the LCVM mixing rule, interaction parameters are calculated for the groups CO 2 /CHO, and revised values for the groups CO 2 /OH are suggested. Finally, for the PSRK mixing rule, revised values are proposed for the interaction parameters between the groups CO 2 /OH and CO 2 /CHO. The results of this work show that the PSRK is the method that best predicts the phase equilibria for the systems studied, with a quadratic mean deviation lower than 5.5%. © 2003 Elsevier B.V. All rights reserved. Keywords: Phase equilibria; Prediction; Mixing rules; Wine; Carbon dioxide 1. Introduction Wine is one of the most complex alcoholic beverages, mainly due to the presence of numerous volatile organic compounds, of which more than 800 have already been identified [1,2]. These compounds belong to a wide variety of chemical families, namely, acids, esters, alcohols, aldehydes, lactones, terpenes, ∗ Corresponding author. Tel.: +351-22-508-1660; fax: +351-22-508-1449. E-mail address: dbarbosa@fe.up.pt (D. Barbosa). nor-isoprenoids, pyrazines, and many others. The characteristic bouquet of a wine is largely the balance of the contribution of these different compounds and not the result of an individual impact. Therefore, it seems clear that the implementation of a dealcoholiza- tion process, in which the main goal is to remove the ethanol while preserving the organoleptic proper- ties of the wine, is a very complex and challenging problem. In recent years, supercritical fluid extraction with carbon dioxide has been suggested as a promising alternative to other conventional dealcoholization 0896-8446/$ – see front matter © 2003 Elsevier B.V. All rights reserved. doi:10.1016/j.supflu.2003.09.018