Modification of stevioside using transglucosylation activity of Bacillus amyloliquefaciens α-amylase to reduce its bitter aftertaste

Stevioside is a natural high-intensity sweetener with low calorie. However, the intrinsic bitter aftertaste limits its application in food products. Transglucosylation of stevioside by α-amylase from Bacillus amyloliquefaciens in the starch solution to produce transglucosylated steviosides with reduced bitter aftertaste was investigated. Under the optimal conditions, the conversion yield of stevioside attained 38.3%. Two major transglucosylated steviosides, which accounted for 96 g/100 g of the total transglucosylated steviosides, were identified to be 13-{[2-O-(β-d-glucopyranosyl)-β-d-glucopyranosyl]oxy} ent-kaur-16-en-19-oic acid 2-O-(α-d-glucopyranosyl)-β-d-glucopyranosyl ester, and 13-{[2-O-(β-d-glucopyranosyl)-β-d-glucopyranosyl]oxy} ent-kaur-16-en-19-oic acid 2-O-[(4- O-α-d-glucopyranosyl)-α-d-glucopyranosyl]-β-d-glucopyranosyl ester by liquid chromatography-tandem mass spectrometry and nuclear magnetic resonance spectroscopy. Sensory evaluation demonstrated that, by enzymatic modification, the sweetness of two major transglucosylated steviosides was significantly improved and the bitter aftertaste was significantly reduced.

► Transglucosylation of stevioside by commercial α-amylase BAN 480L was studied.
► Two new transglucosylated steviosides were isolated and identified for the first time.
► Bitter aftertaste of the modified stevioside has been significantly reduced.