不同酶改性木薯淀粉及其结构分析

Structural Analysis of Cassava Starch Modified by Different Enzymes

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(FT-IR)、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。

Cassava starch was modified using enzymes of different types at various amounts and at different ratios.The structures of the modified cassava starch were investigated using scanning electron microscopy(SEM),X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR),polarizing microscopy(PLM),and differential scanning calorimetry(DSC).The results show that with a larger enzyme dosage,a higher glucoamylase ratio,and the addition of protease,the particle size of starch decreases and particle surface erodes over a large area to form pits.The crystalline region of starch is also hydrolyzed by enzymes to form a hollow structure.The cross extinction of starch granules was weakened or even disappeared.Different enzyme dosages and ratios,as well as the addition of protease,did not cause starch molecules to form new functional groups.The 2θ diffraction angle of natural cassava starch exhibited diffraction peaks at 5.6°,15°,17.2°,22°,and 24°,indicating the formation of B crystals.The starch modified by enzymes demonstrated the A crystal patterns with diffraction peaks at 15°,17.1°,18°,and 23°.Enzyme modification increased the gelatinization temperature of cassava starch from 65.43℃ to 69.11℃.The results suggest that different enzyme dosages,ratios and types will cause different structural changes by hydrolyzing the surface and inside of cassava starch particles.The findings help to reveal the mechanism of enzyme modification on cassava starch,providing a theoretical basis for further research on the application of cassava starch.