Production of rubusoside from high concentration of stevioside with or without rebaudioside A and its performance in micelle solubilization

The reaction pathway of Ru production and its solubilization on vitamin. • Rubusoside is produced from 55 wt.% of stevioside with a conversion of 98.8 %. • Reaction pathway of rubusoside production from stevioside with or without rebaudioside A. • 1% rubusoside promoted the solubility of vitamin E and D 2 at 25℃ by 10 5 and 111 times, respectively. Rubusoside is a natural botanic sweetener with capacity of micelle solubilization. This study revealed the reaction pathway of enzymatically producing rubusoside from a high concentration of stevioside in the absence or presence of rebaudioside A, the identification of the byproduct, as well as the performance of rubusoside in micelle solublization of vitamins. Rebaudioside A initially stimulated rubusoside yield by taking glucosyl from stevioside to form monoglucosyl rebaudioside A, although the β -glucosidase administered was absolutely specific towards stevioside. A trace byproduct was identified as steviol glucosyl ester, yielded from breaking the 13-( β -D-glucopyranosyloxy) linkage of stevioside instead of that of rubusoside. 1% Rubusoside promoted the solubility of vitamin E (VE) and vitamin D 2 at 25℃ by 10 5 and 111 times, respectively. The driving force for the solubilizing is the synergic effect of VE and rubusoside on the surface activity of rubusoside solution, presented as the erasing of the γ-lgC plateau by VE with increasing concentration, which dramatically increased the concentration for micelle formation. The results are beneficial for the use of concentrated stevia ( Stevia rebaudiana Bertoni) extracts to produce rare natural steviol glycoside, yet extend its application in addition to its function as a sweetener.