魔芋葡甘聚糖与低酰基结冷胶共混溶液的性质研究

本文以魔芋葡甘聚糖和低酰基结冷胶为研究对象，研究了魔芋葡甘聚糖与低酰基结冷胶共混溶液的流变性、热稳定性及结晶行为。采用同步辐射X-射线衍射分析晶态变化，流变仪分析溶胶在45 ℃和25 ℃下的频率依赖性和5~80 ℃温度范围内的温度依赖性，差示扫描量热分析法测定溶胶热稳定性变化。发现魔芋葡甘聚糖/低酰基结冷胶的同步辐射X-射线衍射图样弧形层线比低酰基结冷胶的少且模糊，没有观察到径向反射线，加入魔芋葡甘聚糖后，低酰基结冷胶的晶体结构被破坏；与低酰基结冷胶相比较，魔芋葡甘聚糖/低酰基结冷胶共混体系的储能模量G'降低，更趋于流体，对频率稳定性降低，对温度的稳定性提高；微波处理会加剧魔芋葡甘聚糖对低酰基结冷胶的影响，降低热稳定性。结果表明，魔芋葡甘聚糖不利于低酰基结冷胶凝胶网络及晶体结构形成。
The rheological properties, thermal stability, and crystallization behavior of konjac glucomannan and low-acyl gellan gum blends were studied. The changes in crystal structure were analyzed by synchrotron radiation X-ray fiber diffraction. The frequency dependences at 45 ℃ and 25 ℃ as well as the temperature sweep in the range of 5~80 ℃ were measured using a rheometer, and the changes in thermal stability were measured using the modulated differential scanning calorimetric technique. The cambered layer lines from the X-ray fiber diffraction of konjac glucomannan and low-acyl gellan gum blend were decreased and much vaguer than that of the low-acyl gellan gum. The reflected rays were not observed in the radical direction after X-ray fiber diffraction of the blend, which indicates that the crystal structure of the low-acyl gellan gum was broken by konjac glucomannan. Compared with low-acyl gellan gum, the blend had lower storage modulus G', showed more fluid-like characteristics, and had lesser stability against changes in frequency. However, its stability against temperature changes was enhanced. The influence of konjac glucomannan on low-acyl gellan gum was enhanced by microwave treatment. The results suggested that konjac glucomannan did not facilitate network formation and crystal structure development in low-acyl gellan gum.