微波对玉米淀粉结构及理化性质的影响

本实验采用微波（累积能量值为1 680 J/g）处理不同的淀粉-水体系，观察淀粉颗粒形态的变化，并测定透明度、沉降物体积、吸水率、持水性、相对结晶度和流变特性等指标。结果表明，随着淀粉-水体系中水分质量分数的增加，淀粉颗粒的完整性和偏光十字逐渐减弱；与玉米淀粉相比，微波处理淀粉乳透明度、沉降物体积、吸水率和持水性明显增加；X射线衍射图谱表明微波处理后淀粉颗粒仍为A型而相对结晶度下降，说明微波处理破坏了淀粉的结晶结构；微波处理没有改变淀粉乳流体的类型，弹性模量均大于黏性模量，表明均以弹性性质为主。结论：微波处理淀粉-水体系对淀粉的颗粒结构和理化特征均有显著影响，本研究结果可为开发具有独特理化性质的改性淀粉或改进淀粉改性工艺提供实验与理论依据。

Effect of Microwave on the Structure and Physicochemical Properties of Maize Starch

In this study, a starch-water system was treated with microwave at a cumulative energy of 1 680 J/g of maize starch (MS) and was evaluated for changes in granular morphology, transparency, sediment volume, water absorption capacity, water holding capacity, relative crystallinity and rheological properties. The results showed that the structural integrity and birefringence of the starch granules was weakened with increasing water content in the starch-water system. The transparency, sediment volume, water absorption capacity and water-holding capacity of the starch suspension were significantly increased after microwave treatment. The X-ray diffraction pattern showed that the crystal type (A-type) of the starch granules was not changed while the relative crystallinity was decreased after the microwave treatment, indicating that the microwave treatment destroyed the crystalline structure of the starch. The elastic modulus of the starch suspension was greater than the viscous modulus, indicating the dominance of elasticity, which was not changed by the microwave treatment. These results show that microwave treatment of starch-water systems can significantly affect the granular structure and physicochemical characteristics of starch, which may provide an experimental and theoretical basis for the development of modified starches with unique physicochemical property and for the improvement of starch modification process.