Supercritical fluid extraction from Stevia rebaudiana Bertoni using CO2 and CO2 plus water:: extraction kinetics and identification of extracted components

Stevia rebaudiana Bertoni contains glycosides, which are insoluble in carbon dioxide and soluble in mixtures of carbon dioxide and a polar solvent. The purpose of this work was to studs the supercritical fluid extraction of these glycosides from stevia leaves using a two-step process: (i) CO2 extraction at 200 bar and 30 degreesC, and (ii) CO2 + water extraction. The chemical compositions of the extracts were analyzed by GC-FID. GC-MS. TLC and HPLC. The overall extraction curves for the system stevia + CO2 had the typical shape and were successfully described by the Sovova's model, Approximately 72% of the CO2-soluble compounds were recovered and the major compound was austroinulin. The system stevia + CO, + water behaved as expected at 10 and 16 degreesC and 120 and 250 bar but its behavior was unusual at 30 degreesC and 250 bar. The process removed approximately 50% of the original stevioside and about 72% of the rebaudioside A. (C) 2002 Elsevier Science Ltd. All rights reserved.