Abstract
Incubation of rubusoside with raffinose in the presence of various α-galactosidases yielded three galactosylated rubusosides. Mortierella vinacea α-galactosidase transferred a galactosyl residue preferentially to the C6-hydroxyl group of the glucosyl residue at the 13-hydroxyl group of rubusoside to produce mainly 13-O-α-D-galactosyl-(1→6)-β-D-glucosyl-19-O-β-D-glucosyl-steviol. α-Galactosidases from Absidia veflexa, Escherichia coli, and coffee beans transferred a galactosyl residue to the C6-hydroxyl group of both glucosyl residues at the 13-hydroxyl and 19-carboxyl groups of rubusoside, yielding the above galactosylated rubusoside and 13-O-β-D-glucosyl-19-O-α-D-galactosyl-(1→6)-β-D-glucosyl-steviol.
