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

Abstract

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 ~ 65%, a mixture of ST derivatives was produced by adding 1– 6 glucosyl units to the ST molecule. By further treatment with α-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.