Enzymic production of sweet stevioside derivatives: transglucosylation by glucosidases.

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 alpha-glucosidases gave glucosylated products. Transglucosylation of stevioside by Pullulanase and pullulan exclusively afforded three products, 13-O-[beta-maltotriosyl-(1----2)-beta-D-glucosyl]-19-O-beta-D-g luc osyl- steviol (1), 13-O-[beta-maltosyl-(1----2)-beta-D-glucosyl]-19-O-beta-D-glucosyl- steviol (2) and 13-O-beta-sophorosyl-19-O-beta-maltotriosyl-steviol (3). All of these products have already been obtained by trans-alpha-1,4-glucosylation of stevioside by the cyclodextrin glucanotransferase 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-beta-sophorosyl-19-O-beta-isomaltosyl-steviol (4), 13-O-[beta-isomaltosyl(1----2)-beta-D-glucosyl]-19-O-beta-D-glucosyl- steviol (5) and 13-O-[beta-nigerosyl-(1----2)-beta-D-glucosyl]-19-O-beta-D- glucosyl-steviol (6). A significantly high quality of taste was evaluated for 4.