Supercritical fluid extraction from Stevia rebaudiana Bertoni using CO2 and CO2+water: extraction kinetics and identification of extracted components Original Research Article

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 study the supercritical fluid extraction of these glycosides from stevia leaves using a two-step process: (i) CO2 extraction at 200 bar and 30 °C, 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 Sovová’s model. Approximately 72% of the CO2-soluble compounds were recovered and the major compound was austroinulin. The system stevia+CO2+water behaved as expected at 10 and 16 °C and 120 and 250 bar but its behavior was unusual at 30 °C and 250 bar. The process removed approximately 50% of the original stevioside and about 72% of the rebaudioside A.