β-葡聚糖酶降解魔芋葡甘聚糖产物的制备及结构表征

魔芋葡甘聚糖（konjac glucomannan,KGM）可被β-葡聚糖酶降解，对其降解产物的结构特性进行了研究。利用X射线衍射、傅里叶变换红外光谱、扫描电子显微镜鉴定KGM及其酶解产物的结构特征变化，并结合多角度激光光散射-凝胶渗透色谱法测定KGM及其产物的分子质量，测定其特征黏度、脱乙酰度、可溶性多糖含量、电学特性等对酶解产物进行化学特性评估。结果表明：与原KGM相比，KGM酶解产物的主链结构没有改变，原KGM经过5倍酶量酶解120 min后，可能存在较弱的结晶区，扫描电子显微镜结果显示酶解产物表面片层化，且分子质量减小至（36.48±1.23）kDa，特征黏度减小了98%，脱乙酰度显著增大（P<0.05），可溶性总糖含量显著降低（P<0.05）。本研究可为KGM酶解改性的应用提供参考，促进KGM酶解产物资源的高价值利用。

Preparation and Structural Characterization of β-Dextranase Hydrolytic Products of Konjac Glucomannan

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.