Isolation of Stevioside and related compounds from two types of Stevia rebaudiana (Bertoni) species from Bangladesh.

Abstract

The sweet Stevia rebaudiana (Bert.) leaf of South American region mainly contains Stevioside and rebaudioside-A which are two commercially important diterpenoid glycoside. Stevioside is 300 times sweeter than sugar, while rebaudioside-A is 1.6 to 1.8 times sweeter than stevioside. Some of the modern techniques of extraction and purification have been found to be complex and expensive. Therefore, the aim of the work reported here was to extract and purify stevioside and rebaudioside A using easy, simple and less expensive way. A solvent Extraction method has been chosen to evaluate the individual effect of different solvents (i.e. water, acidic, basic, methanol and ethanol solvent), time, temperature, pH. Dried leaves were blended to make fine powder and macerated by using different solvents at different temperature and time. Best result was found with 70% ethanol solution which procedure is less time consuming and can be carried out at room temperature. The stevia powder to ethanol solvent ratio was 1:15. Percentage of yield obtained after completing extraction steps was 24.71% which needs to undergo further purification process to obtain pure stevioside and rebaudioside A crystals. This green extraction process provided a simple and cost effective path to obtain almost pure stevioside and rebaudioside A.