A comparative study of the ability of different solvents and adsorbents to extract aroma compounds from alcoholic beverages.

Seven liquid solvent systems--dichloromethane, dichloromethane-pentane (1:1), freon 113, diethyl ether-pentane (1:1 and 1:9), ethyl acetate-pentane (with and without an additional salting-out effect) (1:3 and 1:20), and seven solid-phase extraction (SPE) systems (Amberlite XAD-2, 4, 7, and 16; Porapak Q; C8; and C18)--are comparatively studied. The distribution coefficients between the extraction system and a hydroalcoholic solution (12% v/v in ethanol, pH = 3.2) of 14 selected volatile compounds belonging to different chemical families and polarities are calculated. The results are processed by factor analysis and cluster analysis, and the following conclusions are reached. First, the efficiency of extraction decreases in this order: polymeric sorbents > silica-based sorbents > liquid-liquid systems with salting-out effect approximately dichloromethane > rest of liquid solvents. Second, the addition of salt mainly increases the recovery of compounds with Lewis acid properties. Third, the efficiency of the extraction of a liquid solvent depends not only on its polarity but also on its solubility in water. Fourth, in regards to the selectivity of the SPE systems, Porapak Q is the best to extract nonpolar compounds, Amberlite XAD 4 and 16 provide the least selective extraction profiles, and C8 and C18 have a special ability to extract compounds with a Brønstedt-Lowry character. Results indicate that in all cases liquid solvents can be replaced satisfactorily by SPE systems.