Abstract:

This study explored the preparation of glucomanno-oligosaccharides by the hydrolysis of konjac gum with
purity more than 95% using a new high-yield β-mannanase with high degradation efficiency of hemicellulose secreted by
Bacillus subtilis BE-91. Based on one-factor-at-a-time experiments, a four-variable, three-level orthogonal array design was
applied to optimize the hydrolysis process of konjac gum, and thin layer chromatography (TLC) was used to qualitatively
analyze the products. Results showed that the optimal experimental conditions that provided maximum hydrolysis efficiency
(35.96%) were determined as follows: konjac gum concentration, 0.33 g/100 mL; β-mannanase dosage, 6 U/g; hydrolysis
time, 1 h; and hydrolysis temperature, 60 ℃. The hydrolysis rate of the konjac gum obtained under these optimal conditions
was 35.96%. The hydrolysis products were mostly oligosaccharides with a polymerization degree of 2–6. The enzymatic
approach to the preparation of glucomanno-oligosaccharides possesses the advantages of lower enzyme consumption, shorter
hydrolysis time, and higher-purity products which have broad application prospects in the preparation of functional foods.

Key words: Bacillus subtilis BE-91, β-mannanase, konjac gum, glucomanno-oligosaccharides, process