Determination of solubility and metastable zone of Rebaudioside A in ethanol-isopropanol-water system

The solubility and supersolubility curves of Rebaudioside A ( RA) in ethanol-isopropanol-water system were determined using the dynamic stabilization method. The solubility of RA at the different composition of solvent was also measured.Furthermore, the polynomial empirical equation was used to correlate the experimental data. The results showed that the solubility of RA increased with the temperature in ethanol-isopropanol-water system and decreased with the increasing of isopropanol's proportion, furthermore, it increased with increasing of H₂O's proportion. Moreover, the metastable zone width decreased with the increasing of temperature from 0 to 60 ℃.The metastable zone width was about 4 to 7 ℃. The error of polynomial empirical equation was small and it provided essential data for the crystallization process of Rebaudioside A.