SEPARATION OF ANTIOXIDANT COMPONENTS FROM WHITE GRAPE SKIN AND SEEDS USING COMPRESSED CARBON DIOXIDE. Catarina M.M. Duarte,* Ana A. Matias, Ana V. M. Nunes, M. Rosário Bronze, Helena I. Motta Veiga, M. Nunes da Ponte. Instituto de Biologia Experimental e Tecnológica, Aptd. 12 – 2780 Oeiras, Portugal. Email: cduarte@itqb.unl.pt Fax: 351-21-4421161 The possibility of extracting antioxidant components with supercritical carbon dioxide from a hydroalcoholic mixture was investigated. High-pressure phase equilibrium behaviour on quaternary systems (CO 2 + ethanol + water + antioxidant compound) was investigated at 40ºC and between 15 and 19 MPa. The separation factors for mixtures of different compositions – 60%(v/v) water + 40% (v/v) ethanol and 90 %(v/v) water + 10%(v/v) ethanol were determined and compared. The viability of scCO 2 extraction process is discussed for Quercetin-3-glucoside. Different combinations of pressures and solvent ratios were studied. The separation factors are determined and discussed. INTRODUCTION Since the last decade there is a considerable interest in the food industry and in preventive medicine in the development of “natural antioxidants” from plant material.[1] Grapes, wines and grape byproducts contain large amounts of phenolic compounds, mostly flavonoids, at high concentrations.[2] Previously, several studies have reported grape’s phenolic composition, which, comprises flavonols, flavan-3-ols and hydroxycinnamic acids. The polyphenolic compounds present in grapes pass to wine more or less depending on the characteristics of the wine making process, however a high proportion remains in the wine production residues or wastes.[3] The work presented is part of a major project designed to study the viability of an alternative clean process for the extraction of antioxidant compounds from botanical source matter. Supercritical carbon dioxide is perceived as a non-toxic solvent. If it is to be used only in a second step of a separation process, the first extraction should use one of the few other solvents that are also considered suitable for contact with products for human consumption. Hydroalcoholic mixtures are in this category and they are currently used to extract many different substances from plants. Moreover, phase equilibrium in the ternary system water + ethanol + carbon dioxide has been extensively studied.[4] In this work, several extractions using dried solid mixtures of white grape skin and seeds, as the matrix feed, were performed using different water-ethanol compositions. Furthermore the possibility of extracting the antioxidant compounds from the hydroalcoholic mixtures using supercritical fluid extraction was studied. This possibility is attracting considerable interest in