High-purity Rebaudioside D
The invention provides methods of purifying Rebaudioside D from the Stevia rebaudiana Bertoni plant extract along with Rebaudioside A. The methods are useful for producing high purity Rebaudioside D and Rebaudioside A. The high purity Rebaudiosides are useful as non-caloric sweeteners in edible and chewable compositions such as any beverages, confectionaries, bakeries, cookies, chewing gums, and alike.
1. A method for purifying Rebaudioside D from Stevia extract comprising the steps of:
a. providing an extract of Stevia rebaudiana Bertoni plant;
b. dissolving the extract in a first aqueous solution of organic solvent to result in a first mixture of steviol glycosides, wherein the organic solvent is selected from the group consisting of methanol, ethanol, l-propanol, isopropanol, and a mixture thereof, and the organic solvent is 75-99 vol. %;
c. inducing crystallization in the first mixture;
d. filtering the mixture from step (c) to obtain a first precipitate and a first filtrate;
e. dissolving the first precipitate in a second aqueous solution of organic solvent to result in a second mixture, wherein the organic solvent is selected from the group consisting of methanol, ethanol, l-propanol, isopropanol, and a mixture thereof, and the organic solvent is 70-80-vol. %;
f. inducing crystallization in the second mixture;
g. filtering the mixture from step (f) to obtain a second precipitate and a second filtrate;
h. dissolving the second precipitate in a third aqueous solution of organic solvent to result in a third mixture, wherein the organic solvent is selected from the group consisting of methanol, ethanol, l-propanol, isopropanol, and a mixture thereof, and the organic solvent is 10-80 vol. %;
i. inducing crystallization in the third mixture; and
j. filtering the mixture from step (i) to obtain a third precipitate and a third filtrate;
whereby drying the third precipitate yields purified Rebaudioside D.
2. The method of claim 1 , wherein the first aqueous solution of organic solvent is an ethanol-water solution with 75-99% ethanol.
3. The method of claim 1 , wherein the second aqueous solution or organic solvent is an ethanol-water solution with 70-80% ethanol.
4. The method of claim 1 , wherein the third aqueous solution of organic solvent is an ethanol-water solution with 10-80% ethanol.
5. The method of claim 1 , wherein the step of (c) inducing crystallization in the first mixture comprises adding Rebaudioside A.
6. The method of claim 1 , wherein the first filtrate is concentrated into a steviol glycoside mixture.
7. The method of claim 1 , wherein the second filtrate is added with Rebaudioside A to promote crystallization of Rebaudioside A; thereby the crystallized Rebaudioside A is recovered to yield Rebaudioside A with a purity of 97-99% by weight on a dry basis.
8. The method of claim 1 , wherein the step of (i) inducing crystallization in the third mixture comprises adding Rebaudioside D with at least about 91% to 100% purity to promote crystallization.
9. The method of claim 1 , further comprising:
k. dissolving the third precipitate in a fourth aqueous solution of organic solvent to result in a fourth mixture, wherein the organic solvent is selected from the group consisting of methanol, ethanol, l-propanol, isopropanol, and a mixture thereof, and the organic solvent is 10-80 vol. %;
l. inducing crystallization in the fourth mixture; and
m. filtering the mixture from step (l) to obtain a fourth precipitate;
whereby drying the fourth precipitate yields Rebaudioside D with purity greater than 95%.
10. The method of claim 9 , wherein the fourth aqueous solution of organic solvent is a methanol-water solution.
11. The method of claim 10 , wherein the concentration of said methanol is 10-80%.
12. The method of claim 9 , wherein the step of inducing crystallization in the fourth mixture comprises adding Rebaudioside D with at least about 91% to 100% purity to promote crystallization.
13. The method of claim 1 , wherein the purified Rebaudioside D comprises Rebaudioside D with a purity greater than about 80% Rebaudioside D by weight on a dry basis.
14. The method of claim 1 , wherein the purified Rebaudioside D comprises Rebaudioside D with a purity greater than about 90% Rebaudioside D by weight on a dry basis.
15. The method of claim 1 , wherein the purified Rebaudioside D comprises Rebaudioside D with a purity greater than about 95% Rebaudioside D by weight on a dry basis.
16. The method of claim 1 , wherein the purified Rebaudioside D comprises Rebaudioside D with a purity greater than about 97% Rebaudioside D by weight on a dry basis.
17. The method of claim 1 , wherein the purified Rebaudioside D comprises Rebaudioside D with a purity greater than about 98% Rebaudioside D by weight on a dry basis.
18. The method of claim 1 , wherein the purified Rebaudioside D comprises Rebaudioside D with a purity greater than about 99% Rebaudioside D by weight on a dry basis.