不同质量分数大米淀粉凝胶速冻后精细结构和流变学特性研究

Study on fine structure and rheological properties of rice starch gels with different mass fractions after quick-freezing

采用扫描电子显微镜、X射线衍射仪、傅里叶变换红外光谱仪、激光共聚焦显微拉曼光谱仪、差式扫描量热仪、质构仪、低场核磁水分分布仪和流变仪分析质量分数4%、8%、12%、16%大米淀粉凝胶经速冻-短时冻藏后的精细结构和流变学特性变化。结果表明:随着大米淀粉凝胶质量分数的增大,经速冻-短时冻藏后的大米淀粉凝胶样品的有序性与相对结晶度先减后增,其中质量分数12%的大米淀粉有序性和相对结晶度均最低,其微观结构更加均匀致密;凝胶玻璃化转变温度和熔融温度提高,自由水含量降低,稠度系数K增大,流体指数n减小,在试验范围内大米淀粉凝胶流体属于剪切变稀的非牛顿流体;大米淀粉凝胶黏弹性、强度和硬度增强。

Scanning electron microscope,X-ray diffractometer,Fourier transform infrared spectrometer,laser confocal micro Raman spectrometer,differential scanning calorimeter,texture analyzer,low field nuclear magnetic resonance moisture distribution meter and rheometer were used to analyze the changes of fine structural and rheological properties of mass fraction 4%,8%,12%and 16%rice starch gel after quick-freezing to short freezing storage.The results showed that with the increase of mass fraction of rice starch gel,the orderliness and relative crystallinity of rice starch gel samples after quick-freezing to short-freezing stroage decreased first and then increased.The orderliness and relative crystallinity of rice starch gel samples with mass fraction of 12%were the lowest,and its microstructure was more uniform and dense.The glass transition temperature and melting temperature increased.The free water content decreased.The consistency coefficient K increased,and the fluid index n decreased.The rice starch gel fluid belonged to shear-thinning non-Newtonian fluid in the test range.The viscoelasticity,strength and hardness of rice starch gel were enhanced.