激光对魔芋葡甘聚糖降解的初步探究

Preliminary Study on Degradation of Konjac Glucomannan by Laser

为降低魔芋葡甘聚糖(KGM)的分子质量,提升其在食品、医药、材料等领域的应用潜力,采用激光辅助过氧化氢的方法对质量浓度为0.01g/mL的KGM溶液进行降解,借助粘度计、流变仪初步确定较优的降解条件,再利用差示扫描量热法(DSC)、傅里叶变换红外(FT-IR)光谱仪对筛选出的KGM降解产物进行表征,并初步探究出其降解机理。结果表明:当激光功率为10 W,过氧化氢的体积分数为1.5%,处理时间为2min时,KGM的降解效果较佳,黏度由7.2Pa·s降至3.17Pa·s;在该降解条件下得到的KGM降解产物的储能模量与损耗模量的交汇点后移,分子间的缠结减弱,分子质量减小;DSC热吸收峰对应的温度由301℃升为326℃,热稳定性升高;降解前后KGM的红外光谱无明显变化,特征官能团保持不变。本研究可为KGM的有效降解提供一种新思路。

In order to reduce the molecular weight of konjac glucomannan （KGM）, and enhance its application in the fields of food, medicine and materials, we adopt the laser combination with hydrogen peroxide to degrade the KGM solution of 0.01 g/mL. Viscosity meter and rheometer are used to determine the better degradation conditions, and then differential scanning calorimetry （DSC） and Fourier transform infrared （FT-IR） spectroscopy are used to characterize the selected KGM degradation products, and the degradation mechanism is studied preliminarily. The results show that the viscosity of KGM decreases from 7.2 Pa. s to 3.17 Pa. s when the laser power is 10 W, the volume fraction of hydrogen peroxide is 1.5%, and the treatment time is 2 min. For the KGM obtained under the above condition, the intersection point of storage modulus and loss modulus moves backward, the intermolecular entanglement weakens and the molecular mass reduces. The temperature corresponding to thermal absorption peak of DSC increases from 301 ＊C to 326 ℃, and the thermal stability rises. There are no significant changes in the infrared spectra of KGM before and after degradation, and the characteristic functional groups remain unchanged. This study can provide a new idea for the effective degradation of KGM.