Rebaudioside A Composition and Method for Purifying Rebaudioside A

1. A method for purifying rebaudioside A comprising the steps of:

combining crude rebaudioside A and an aqueous organic solvent to form a rebaudioside A solution, the aqueous organic solution comprising water in an amount from about 10% to about 25% by weight; and

crystallizing from the rebaudioside A solution in a single step a substantially pure rebaudioside A composition comprising rebaudioside A in a purity greater than about 95% by weight on a dry basis.

2. The method of claim 1, further comprising the step of heating the rebaudioside A solution.

3. The method of claim 2, further comprising the step of cooling the rebaudioside A solution.

4. The method of claim 1, wherein rebaudioside A solution in the single crystallization step is stirred or unstirred.

5. The method of claim 1, further comprising the step of seeding (optional) the rebaudioside A solution at an appropriate temperature with an amount of rebaudioside A sufficient to promote crystallization of rebaudioside A.

6. The method of claim 1, further comprising the steps of separating and washing the substantially pure rebaudioside A composition.

7. The method of claim 6, further comprising the step of drying the substantially pure rebaudioside A composition.

8. The method of claim 1, wherein the crude rebaudioside A comprises substantially no rebaudioside D impurity, and the method further comprises slurrying the substantially pure rebaudioside A composition in an aqueous organic solvent or in an organic solvent.

9. The method of claim 8, further comprising the steps of separating and washing the substantially pure rebaudioside A composition.

10. The method of claim 9, further comprising the step of drying the composition of a substantially pure rebaudioside A.

11. The method of claim 1, wherein the aqueous organic solvent comprises a mixture of at least one organic solvent and water.

12. The method of claim 11, wherein at least one organic solvent comprises an alcohol.

13. The method of claim 12, wherein the alcohol comprises ethanol.

14. The method of claim 12, wherein the alcohol comprises methanol.

15. The method of claim 12, wherein the alcohol comprises a mixture of ethanol and methanol.

16. The method of claim 15, wherein the ethanol and methanol are present in the aqueous organic solution in a weight ratio from about 20 parts to about 1 parts ethanol to about 1 part methanol.

17. The method of claim 15, wherein the ethanol and methanol are present in the aqueous organic solution in a weight ratio from about 3 parts to about 1 part ethanol to about 1 part methanol.

18. The method of claim 1, wherein the at least one aqueous organic solvent comprises an organic solvent selected from the group consisting of acetone, acetonitrile, methanol, ethanol, 1-propanol, isopropanol, 1-butanol, 2-butanol, tert-butanol, and mixtures thereof.

19. The method of claim 1, wherein the aqueous organic solvent and the crude rebaudioside A are present in the rebaudioside A solution in a weight ratio from about 4 to about 10 parts aqueous organic solvent to about 1 part crude rebaudioside A.

20. The method of claim 1, wherein the aqueous organic solvent and the crude rebaudioside A are present in the rebaudioside A solution in a weight ratio from about 3 to about 5 parts aqueous organic solvent to about 1 part crude rebaudioside A.

21. The method of claim 1, wherein aqueous organic solvent comprises water in an amount from about 10% to about 25% by weight.

22. The method of claim 1, wherein the crude rebaudioside A mixture comprises rebaudioside A in a purity from about 40% to about 95% by weight.

23. The method of claim 1, wherein the crude rebaudioside A mixture comprises rebaudioside A in a purity from about 60% to about 85% by weight.

24. The method of claim 1, wherein the crude rebaudioside A mixture comprises rebaudioside A in a purity from about 70% to about 85% by weight.

25. The method of claim 1, wherein the method is carried out at approximately room temperature.

26. The method of claim 2, wherein the step of heating the rebaudioside A solution comprises heating the rebaudioside A solution to a temperature in a range from about 20° C. to about 40° C.

27. The method of claim 2, wherein the step of heating the rebaudioside A solution comprises heating the rebaudioside A solution to a temperature in a range from about 40° C. to about 60° C.

28. The method of claim 2, wherein the step of heating the rebaudioside A solution comprises heating the rebaudioside A solution to about a reflux temperature.

29. The method of claim 3, wherein the step of cooling the rebaudioside A solution comprises cooling the rebaudioside A solution to a temperature in a range from about 4° C. to about 25° C.

30. The method of claim 3, wherein the step of cooling the rebaudioside A solution comprises cooling the rebaudioside A solution for about 0.5 hours to about 24 hours.

31. The method of claim 1, wherein the substantially pure rebaudioside A product comprises rebaudioside A in a purity greater than about 97% rebaudioside A by weight on a dry basis.

32. The method of claim 1, wherein the substantially pure rebaudioside A product comprises rebaudioside A in a purity greater than about 98% rebaudioside A by weight on a dry basis.

33. The method of claim 1, wherein the substantially pure rebaudioside A product comprises rebaudioside A in a purity greater than about 99% rebaudioside A by weight on a dry basis.

34. The method of claim 1, further comprising the steps of:

heating the rebaudioside A aqueous organic solvent mixture;

cooling the rebaudioside A solution;

separating and washing a substantially pure rebaudioside A composition; and

drying the substantially pure rebaudioside A composition.

35. A substantially pure rebaudioside A composition made according to the method of claim 1, wherein the substantially pure rebaudioside A composition comprises a polymorph having an X-ray diffraction pattern substantially similar to FIG. 7.

36. A substantially pure rebaudioside A composition made according to the method of claim 1, wherein the substantially pure rebaudioside A composition comprises a polymorph having an X-ray diffraction pattern substantially similar to FIG. 8.

37. A substantially pure rebaudioside A composition made according to the method of claim 1, wherein the substantially pure rebaudioside A composition comprises a polymorph having an X-ray diffraction pattern substantially similar to FIG. 9.

38. A substantially pure rebaudioside A composition made according to the method of claim 1, wherein the substantially pure rebaudioside A composition comprises a polymorph having an X-ray diffraction pattern substantially similar to FIG. 10.

39. A substantially pure rebaudioside A composition made according to the method of claim 1, wherein the substantially pure rebaudioside A composition comprises an amorphous form having an X-ray diffraction pattern substantially similar to FIG. 11.

40. The method of claim 1, further comprising the step of forming an amorphous form of the substantially pure rebaudioside A composition.

41. The method of claim 38, wherein the step of forming an amorphous form of the substantially pure rebaudioside A composition comprises a method selected from the group consisting of ball milling, precipitation, lyophilization, cryogrinding, and spray-drying

42. A substantially pure rebaudioside A composition made according to the method of claim 1.