Abstract
For the purpose of improving sweetness and a further study on the structure-sweetness relationship of steviol glycosides, transglycosylation of stevioside by a variety of commercial glucosidases was investigated. It was revealed that two α-glucosidases gave glucosylated products. Transglucosylation of stevioside by Pullulanase and pullulan exclusively afforded three products, 13-O-[β-maltotriosyl(1→2)-β-glucosyl]-19-O-β-D-glucosyl-steviol (1), 13-O-β-maltosyl-(1→2)-β-D-glucosyl]-19-O-β-D-glucosyl-steviol (2) and 13-O-β-sophorosyl-19-O-β-maltotriosyl-steviol (3). All of these products have already been obtained by trans-α-1, 4-glucosylation of stevioside by the cyclodextrin glucano-transferase starch system, and 1 and 2 have been proven to be tasty and potent sweeteners. Transglucosylation of stevioside by Biozyme L and maltose afforded three new products, 4, 5 and 6, the structures of these compounds being elucidated as 13-O-β-sophorosyl-19-O-β-isomaltosyl-steviol(4), 13-O-β-isomaltosyl(1→2)-β-D-glucosyl]-19-O-β-D-glucosyl-steviol (5) and 13-O-β-nigerosyl(1→2)-β-D-glucosyl]-19-O-β-D-glucosyl-steviol (6). A significantly high quality of taste was evaluated for 4.
