3种大米淀粉脱支前后结构及流变特性

通过普鲁兰酶处理糯米、粳米和籼米淀粉，研究酶水解对3 种大米淀粉结构和流变特性的影响。结果表明，经普鲁兰酶处理后3 种大米淀粉的结晶度降低，无定型区域增加；链长分布结果表明3 种大米淀粉的精细结构相似，水解反应对较短的侧链更有效，糯米淀粉更易被酶解；脱支淀粉和天然大米淀粉的傅里叶变换红外光谱没有明显差异，—OH的伸缩振动吸收峰相对增强；添加普鲁兰酶后，淀粉糊黏度急剧下降，糯米淀粉黏度下降最快，较容易被水解；流变学特性表明淀粉颗粒分子间缔合、排列松散，运动性增强，溶解度和持水力有所增强。糯米淀粉对普鲁兰酶处理较其他两种大米淀粉更为敏感。结论：脱支处理改善了淀粉凝胶性能，增强了淀粉的流动性。

Effect of Pullulan on the Structure and Rheological Properties of Starches from Three Rice Varieties

In the present study, debranched starches (DBS) from three rice varieties were prepared by treatment with pullulanase with the aim to investigate the effect of enzymatic hydrolysis on starch structure and rheological properties. The results showed that the crystallinity of rice starch decreased and the amorphous region increased after pullulanase treatment. The chain length distribution showed that the fine structures of the three rice starches were similar, the hydrolysis reaction was more effective for shorter side chains, and glutinous rice starch was more easily digested. There was no significant difference in the Fourier transform infrared spectra of debranched and raw rice starch except that the stretching vibration peak of ?OH was relatively enhanced. Upon the addition of pullulanase, the viscosity of starch paste decreased steeply especially for glutinous rice starch, which was more easily hydrolyzed than the other two rice starches. The rheological properties indicated that the starch granules became intermeshing and loosely arranged after hydrolysis. Moreover, the mobility was increased, and the solubility and water-holding capacity were enhanced. Glutinous rice starch was more sensitive to pullulanase treatment than the other rice starches. To conclude, debranching can improve starch gel properties and enhance starch fluidity .