微波辐射下高含水量木薯淀粉热效应及结晶结构的变化

Influence of Microwave Irradiation on Thermal Property and Crystal Structures of Tapioca Starch with High Moistuse Content

利用红外结晶指数、偏光显微镜等表征手段,考察不同高含水量的木薯淀粉在敞口和封口条件下,经微波辐射后的热效应及其结晶结构的变化。结果表明:木薯淀粉样品含水量越低,样品温度升高幅度越大,且都会出现等温转换,含水量越高等温转换时间越长,尤其是敞口辐射较封口辐射的等温转换更显著;同时,微波辐射会造成木薯淀粉的结晶结构变化,其红外结晶指数下降。

The time-temperature profiles of open or sealed tapioca starch systems with different moisture contents subjected to microwave processing were established and the structures of tapioca starches after irradiations were investigated by the infrared crystalline indices and polarizing microscope. The results indicate that, at both open and sealed systems, the lower the moisture content of tapioca starch, the faster the temperature rise, and the isothermal transformation occurred in the starch samples. The time of isothermal transformation increased with the rise of moisture contents. Moreover, the interval lengths of the isothermal transformation were more obvious with the samples irradiated in open beakers as compared to those processed in sealed beakers. At the same time, polarizing microscope figures indicated that the crystal structure of the tapioca starch changed, and the infrared crystalline indices of the starch samples decreased after irradiation.