Graphical Abstract

Stevioside is a natural sweetener extracted from leaves of Stevia rebaudiana (Bertoni) Bertoni. The occurrence of the sweeteners, their biosynthetic pathway and toxicological aspects are discussed. The metabolism of stevioside is discussed in relation with the possible formation of steviol. The conclusion is that Stevia and stevioside are safe when used as a sweetener.

Abstract

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.