Stepwise membrane filtration for Rebaudioside A and Stevioside enrichment in aqueous and ethanolic stevia extracts

Enriching steviol glycosides derived from the stevia plant is an important step in producing stevia natural sweeteners. This study investigated the enrichment of Rebaudioside A and Stevioside compounds of aqueous and ethanol stevia extracts using cascade membrane filtration techniques. Accordingly, extracts from stevia leaves were processed using membrane filtration techniques such as ultrafiltration and nanofiltration. In particular, the 30 kDa ultrafiltration membrane was highly effective in enriching steviol glycosides. The highest concentrations of Rebaudioside A (21.47 g L-1) and Stevioside (19.97 g L-1) compounds were reached at the 30 kDa ultrafiltration retentate fraction in both aqueous and ethanolic extracts. However, it was found that the permeate fluxes and the extracts obtained after the nanofiltration process had very low concentrations of these compounds. The findings highlight the importance of membrane selection in effectively enriching steviol glycosides.