冻藏处理对糯玉米淀粉微观结构和理化特性的影响

将新鲜糯玉米进行不同冻藏时间(0、10、20、30 d)的处理，通过傅里叶红外光谱仪、便携式拉曼光谱仪、X射线衍射仪、扫描电镜、差示扫描量热仪、快速黏度分析仪等研究冻藏处理对其内部淀粉微观结构和理化性能的影响规律，以期为延缓其品质劣变提供基础数据。结果表明：冻藏处理导致糯玉米淀粉的R_{1 045/1 022}减小，半峰宽增大，相对结晶度降低，淀粉颗粒表面出现凹陷和破碎，粒径变小，且随着冻藏时间的延长，冻藏对玉米淀粉微观结构的破坏更加明显；糯玉米经冻藏处理后，其淀粉的糊化温度、糊化焓值、峰值黏度、崩解值下降，最终黏度和回生值升高，表明冻藏淀粉更容易发生糊化，且糊化黏度降低，但淀粉热糊的稳定性有所提高，更容易发生老化。此外，冻藏处理还可导致玉米淀粉内的抗性淀粉和慢消化淀粉转变为快消化淀粉，表明冻藏具有提高鲜食玉米的消化速率和程度的潜力。

Effect of Frozen Storage on Microstructure and Physicochemical Properties of Waxy Corn Starch

In order to provide basic data for delaying quality deterioration in waxy corn, the microstructure and physicochemical properties of waxy corn starch isolated from fresh and frozen corn (stored at ?18 ℃ for 10, 20 or 30 days) were investigated by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffractometry (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and a rapid viscosity analyzer (RVA). The results showed that frozen storage decreased the ratio between the IR peaks at 1 045 and 1 022 cm-1 (R1 045/1 022) and the relative crystallinity of waxy corn starch, and increased the full width at half height. After frozen storage, pits and cracks appeared on the surface of the starch granules, and their size became smaller. As frozen storage time increased, the microstructure of corn starch was damaged more seriously. After frozen storage, the gelatinization temperature, gelatinization enthalpy, peak viscosity and breakdown value of waxy corn starch decreased, while the final viscosity and retrogradation value increased, indicating that frozen corn starch was more prone to gelatinization and retrogradation. In addition, frozen storage could convert slowly digestible starch and resistant starch into rapidly digestible starch, thereby having the potential to improve the digestion rate and degree of fresh corn.