Modification on the length of glucosyl chain in glucosyl steviol glycosides and its effect on product taste quality

Y The taste quality of steviol glycosides (SG) is highly dependent on the numbers and linkages of glucosyl units connecting to its diterpenoid core. In this work, the transglycosylation of stevioside (ST) catalyzed by cyclodextrin glucanotransferase were optimized initially. At a high conversion rate of similar to 65%, a mixture of ST derivatives was produced by adding 1- 6 glucosyl units to the ST molecule. By further treatment with alpha-glucosidase for 4- 24 h, the length of the glucosyl chain can be reduced to 1- 2 units. Based on a previous investigation, the SG recovered from the mother liquor of stevia production was used as the substrate. Taste quality evaluation on the obtained glucosyl steviol glycosides (GSG) suggested both the sweet and bitter aftertaste were significantly weakened after transglycosylation. The sweetness of GSG was obviously reduced with the increase in glucosyl-chain length, while the licorice flavor caused by the residual polyphenols can also be weakened after enzymatic modification. The GSG products presented unique taste quality different from rebaudioside A (RA) and rebaudioside M (RM), while their overall taste quality was close to that of RM. Conclusively, the research can provide a clean approach to promote the resource utilization of stevia, and new GSG products with improved taste quality can be the potential sweetener for food manufacture.

Automated summary

This study optimized the transglycosylation of stevioside (ST) catalyzed by cyclodextrin glucanotransferase, resulting in a mixture of ST derivatives with 1-6 glucosyl units. The length of the glucosyl chain was further reduced to 1-2 units through treatment with alpha-glucosidase. Taste quality evaluation showed that the sweet and bitter aftertaste of the obtained glucosyl steviol glycosides (GSG) were significantly weakened, and the sweetness decreased with the increase in glucosyl-chain length. The licorice flavor caused by residual polyphenols was also weakened after enzymatic modification. The GSG products had unique taste quality different from rebaudioside A (RA) and rebaudioside M (RM), but their overall taste quality was similar to RM. Overall, this research provides a clean approach to utilize stevia resources and develop GSG products with improved taste quality.