Abstract: Konjac glucomannan (KGM) was degraded by β-glucanase. The structural characteristics of KGM and its hydrolysate were identified by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), and their molecular masses were determined by gel permeation chromatography with multiple angle laser light scattering. The chemical characteristics of the hydrolysate were evaluated by measuring their intrinsic viscosity, deacetylation degree, soluble polysaccharide content and electrical characteristics. The results showed that the major chain structure of the hydrolysate did not change compared with KGM. After 120 min of treatment with a five-fold excess of the enzyme, a weak crystalline region may appear. SEM results showed that the surface of the hydrolysate gradually became lamellated, and its molecular weight decreased to (36.48 ± 1.23) kDa. The characteristic viscosity decreased by 98%, the degree of deacetylation increased significantly (P < 0.05), and the content of total soluble sugar decreased significantly (P < 0.05). This study can provide a reference for the enzymatic modification of KGM to promote the high-value utilization of KGM hydrolysate resources.

Key words: konjac glucomannan; enzymatic modification; microstructure; chemical properties