以木薯淀粉为研究对象，通过改变酶的种类、用量和配比进行改性。利用扫描电镜(SEM)、X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)、偏光显微镜(PLM)和差示扫描量热(DSC)研究改性木薯淀粉的结构变化规律。研究结果表明，随着酶用量的增加、糖化酶配比增大和蛋白酶的添加，淀粉的颗粒尺寸减小，表面被侵蚀形成凹坑；淀粉的结晶区域也受到酶水解形成中空结构。淀粉球晶的十字消光现象减弱甚至消失；不同酶用量、不同酶配比和添加蛋白酶处理并未使淀粉分子形成新的官能团。天然木薯淀粉的衍射角2θ在5.6 °、15 °、17.2 °、22 °和24 °处有衍射峰，说明为B晶型；酶改性后的淀粉显示为在15 °、17.1 °、18 °和23 °处有衍射峰的A晶型。酶改性延缓了木薯淀粉的糊化温度，从65.43 ℃升高到69.11 ℃。研究结果表明不同酶用量、酶配比和酶种类会对木薯淀粉颗粒表面和内部进行酶解，并造成不同结构的变化，通过实验有助于揭示酶对木薯淀粉的改性机理，并为深入研究木薯淀粉的应用提供理论依据。

The cassava starch was taken as the research object, which was modified by changing the type, content and ratio of enzymes. The structures of modified cassava starch were investigated by scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), polarizing microscope (PLM) and differential scanning calorimetry(DSC). The results showed that with the increase of enzyme content, the ratio of glucoamylase and protease, the particle size of starch decreases and the surface is eroded in a large area to form pits. The crystalline region of starch is also hydrolyzed by enzyme to form hollow structure. The cross extinction of granule of starch was weakened or even disappeared. Different enzyme content, ratio and the addition of protease treatment did not make starch molecules form new functional groups. The diffraction angle 2θ of natural tapioca starch has diffraction peaks at 5.6 °, 15 °, 17.2 °, 22 ° and 24 °, indicating that the formation of B crystal. The starch modified by enzyme showed the A type crystal with diffraction peaks at 15 °, 17.1 °, 18 ° and 23 °. Enzyme modification delayed the gelatinization temperature of cassava starch from 65.43 ℃ to 69.11 ℃. The results show that different enzyme dosage, enzyme ratio and enzyme type will hydrolyze the surface and inside of cassava starch particles, and cause different structural changes. The experiment is helpful to reveal the mechanism of enzyme modification on cassava starch, and provides a theoretical basis for further research on the application of cassava starch.

广西自然科学基金(2020GXNSFAA159113)