Stevioside purity

An oral LD50 of 17 g/kg body weight was shown for the Stevia extract (20 % of stevioside) and 15 g/kg for purified stevioside (purity of 93.5%). With rats and mice a LD50 of 8.2 g/kg was found for stevioside by oral intake, and given intraperitoneally, a LD50 of 2.99 g/kg of body weight [18]. 

The purity of the stevioside is not always the same in the various experiments or unknown in some experiments. However, in most experiments the purity of the stevioside used is over 90 % and often over 95%. The impurities occurring in the different stevioside preparations are due to compounds extracted from the Stevia leaves that themselves have been shown to be completely safe. Therefore, the problem of the purity of the stevioside is more a point for academic debate than a matter of concern of human health. Stevioside is safe as well as Stevia leaves and their crude extracts. Therefore, the occurrence of a slightly varying percentage (5-10%) of residual leaf extract in the stevioside preparation will not be... 

Potential widespread use of steviosides requires an easy and effective extraction method. Enzymatic extraction of stevioside from Stevia rebaudiana leaves with cellulase, pectinase, and hemicellulase, using various parameters, such as concentration of enzyme, incubation time, and temperature, has been reported [33]. Purification is achieved through adsorption, colunm chromatography, and ion-exchange electrolytic technique for rebaudioside A, rebaudioside C, and dulcoside A [34]. An ultrafiltration (UF) process was reported for recovery of 45 % steviosides from an extract of leaves. Final purification was achieved by two consecutive mixed bed ion-exchange processes. The ion exchangers improved purity of the final product to 90 % [35]. 

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