[关键词]
[摘要]
以玉米淀粉为原料,戊二酸酐为酯化剂,探讨了在乙醇溶剂中制备戊二酸淀粉酯的过程中淀粉乳初始浓度、反应时间、反应温度和体系pH值对产物取代度的影响,得到制备戊二酸淀粉酯的工艺条件:淀粉乳浓度35%(质量分数,下同),反应时间3 h,反应温度35 ℃,体系pH为8.5。采用傅里叶变换红外光谱(FTIR)、扫描电子显微镜(SEM)、X射线衍射仪(XRD)及差示扫描量热仪(DSC)对产物进行了表征。结果表明:戊二酸淀粉酯中新出现了1733 cm-1处C=O的伸缩振动吸收峰,1555 cm-1处游离的-COO-的反对称伸缩振动吸收峰,说明淀粉分子酯化成功;改性淀粉颗粒表面出现了不同程度的凹陷和破裂;XRD分析显示淀粉改性后仍属于A型晶体结构,表明了反应主要发生在无定形区。DSC热分析说明改性后的淀粉糊化温度及糊化焓值均降低;布拉班德粘度分析则表明了改性后的淀粉峰值粘度有很大的提升。
[Key word]
[Abstract]
In this study, corn starch and glutaric anhydride (GA) were used as the raw material and esterifying agent, respectively, to explore the effects of the initial starch slurry concentration, reaction time, reaction temperature, and pH value (during the preparation of starch glutaric acid ester in ethanol) on the degree of substitution. The conditions used to prepare GA starch were as follows: starch slurry concentration: 35% (m/m); reaction period: 3 h; reaction temperature: 35 ℃; and pH value of the reaction system: 8.5. The product was characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and differential scanning calorimetry (DSC). New absorption peaks corresponding to a C=O stretching vibration at 1733 cm-1 and -COO- antisymmetric stretching vibration at 1555 cm-1 were found in starch glutaric acid ester, indicating the successful esterification of starch molecules. Varying degrees of dents and ruptures were found on the granule surface of the modified starch. The XRD results revealed that the modified starch GA exhibited an A-type diffraction pattern, which confirmed that the reaction mainly occurred in the amorphous region. DSC revealed that the gelatinization temperature and enthalpy of the modified starch were decreased. Analysis by the Brabender viscosity method indicated that the peak viscosity of the modified starch was significantly increased.
[中图分类号]
[基金项目]
广东省国际合作项目(2011B050800004)