Statistical design for optimization of extraction of polyphenols from an inert matrix using carbon dioxide-based fluids

A systematic study concerning the extract ability of eight polyphenolic compounds found in grapes has been performed. The compounds were extracted from spiked sand. An experimental design allowed us to determine the effects of 11 extraction and trap variables on recovery. The relationships between all variables were examined. By applying graphical analysis, the best extraction conditions via supercritical (or near critical) fluid carbon dioxide within the range of the parameters that were studied were obtained. The average recovery of the eight phenols was 88%. After modification of these "best" conditions via a change in modifier content and restrictor/trap temperature, recoveries for all eight studied compounds ranged between 92% and 100%. Polyphenols can, therefore, be quantitatively extracted with a carbon dioxide-based fluid under mild conditions in approximately 30 min from an inert matrix. (C) 1999 Elsevier Science B.V. All rights reserved.