Isolation and Characterization of Oligosaccharides from an Enzymic Hydrolysate of Konjac Glucomannan

Konjac mannan consumed 0.991 moles of sodium metaperiodate per anhydrohexose residue. The Smith degradation of this glucomannan produced large amounts of glycolaldehyde and erythritol, in addition to small amounts of d-mannose, d-glucose and glycerol. Complete acid-hydrolysis of the glucomannan yielded d-mannose and d-glucose in a molar ratio of 1.6:1.00 or 8:5. The hydrolysate of konjac glucomannan by β-mannanase preparation from konjac tubers yielded a mixture of oligosaccharide, from which the following compounds were isolated and identified: (1) M→M, (2) G→M, (3) G→G, (4) M→M→M, (5) G→M→M, (6) M→G→M, (7) G→G→M, (8) M→M→M→M, (9) G→M→M→M, (10) G→M→M→G, (11) G→G→M→M, (12) M→M→M→M→M, (13) G→M→M→M→M. On the basis of the above results, the possible structures of this glucomannan and the specificities of β-mannanase were discussed.