Method for making rebaudioside X
Methods of preparing highly purified steviol glycosides, particularly rebaudiosides A, D and X are described. The method includes expression of UDP-glucosyltransferases from Stevia rebaudiana Bertoni, which are capable converting certain steviol glycosides to rebaudiosides A, D and X. The highly purified rebaudiosides A, D and X, are useful as non-caloric sweetener in edible and chewable compositions such as any beverages, confectioneries, bakery products, cookies, and chewing gums.
1. A method for making Rebaudioside X comprising a step of converting Rebaudioside D to Rebaudioside X using a UDP-glucosyltransferase, wherein the conversion of Rebaudioside D to Rebaudioside X is at least about 50% complete.
2. The method of claim 1 , wherein the UDP-glucosyltransferase comprises any UDP-glucosyltransferase capable of adding at least one glucose unit to Rebaudioside D to form Rebaudioside X.
3. The method of claim 2 , wherein the UDP-glucosyltransferase is capable of adding a glucose unit to a C-19 position of Rebaudioside D.
4. The method of claim 1 , further comprising the step of purifying the Rebaudioside X to a purity of greater than about 80% by weight.
5. The method of claim 1 , further comprising the step of purifying the Rebaudioside X to a purity of greater than about 90% by weight.
6. The method of claim 1 , further comprising the step of purifying the Rebaudioside X to a purity of greater than about 95% by weight.
7. The method of claim 1 , wherein the conversion is at least about 60% complete.
8. The method of claim 1 , wherein the conversion is at least about 70% complete.
9. The method of claim 1 , wherein the conversion is at least about 80% complete.
10. The method of claim 1 , wherein the conversion is at least about 90% complete.
11. The method of claim 1 , wherein the conversion is at least about 95% complete.
12. The method of claim 1 , wherein the UDP-glucosyltransferase is expressed in a host microorganism.
13. The method of claim 12 , wherein the UDP-glucosyltransferase host microorganism is selected from the group consisting of: Escherichia coli, Saccharomyces species, Aspergillus species, and Pischia species.
14. The method of claim 1 , wherein the UDP-glucosyltransferase comprises UGT76G1.