戊二酸蜡质玉米淀粉酯的制备及理化性质研究

以原蜡质玉米淀粉为原料，戊二酸酐为酯化剂，乙醇为反应溶剂制备戊二酸淀粉酯(EGAS)。采用傅里叶变换红外光谱（FT-IR）、扫描电子显微镜（SEM）、X射线衍射仪（XRD）及布拉班德粘度仪等对样品进行表征及理化性能分析。结果表明：FT-IR显示戊二酸淀粉酯在1730 cm-1处和1565 cm-1处出现了新的吸收峰，其中1730 cm-1处为C=O的伸缩振动吸收峰，1565 cm-1处为游离的-COO-的反对称伸缩振动吸收峰，表明了淀粉分子中成功接入了戊二酸基团；改性前后淀粉的表观形貌变化，证实了反应不仅发生在淀粉颗粒表面，也发生在淀粉颗粒内部；XRD分析显示改性后的淀粉仍属于A型结晶结构，表明了反应主要发生在无定形区；布拉班德粘度分析则表明了改性后的淀粉（DS=0.0450）峰值粘度提高了2.33倍；EGAS的冻融稳定性和抗剪切力均强于原淀粉，糊的透明度得到改善。

Preparation and Physicochemical Properties of Glutaric Acid Waxy Corn Starch Ester

Native waxy corn starch was used as the raw material to prepare glutaric acid starch ester (EGAS), with glutaric anhydride (GA) as the esterifying agent and ethanol as the solvent. The structural characteristics and physicochemical properties of the samples were determined by Fourier transform infrared (FT-IR) spectroscopy), Brabender viscoamylography, scanning electron microscopy (SEM), and X-ray diffraction (XRD). The results indicated that two new absorption peaks of EGAS appeared at 1730 cm-1 and 1565 cm-1, which were attributed to the stretching vibration of C=O and antisymmetric stretching vibration of free -COO-, respectively. The findings above indicated that the ester carbonyl group was successfully introduced into starch molecules. Changes in the surface morphology of starch granules before and after modification demonstrated that the reaction occurred not only on the surface of starch granules, but also within the granules. XRD revealed that the modified starch still exhibited an A-type diffraction pattern, confirming that the reaction mainly occurred in the amorphous region. Brabender viscoamylography indicated that the peak viscosity of the modified starch (degree of substitution DS]=0.0450) was increased by 2.33 times compared with that of native starch. The freeze-thaw stability and shear force of EGAS were higher than those of native starch, and paste transparency was improved.