机械活化协同微波法制备高取代度柠檬酸酯淀粉

在微波辐射条件下,以不同机械活化时间的木薯淀粉为原料,柠檬酸为酯化剂,氢氧化钠为催化剂制备柠檬酸酯淀粉。以取代度和反应效率为指标,分别探讨机械活化时间、微波功率、微波辐射时间、淀粉含水量、柠檬酸用量及氢氧化钠用量对木薯淀粉柠檬酸酯化反应的影响,并对影响因素进行了正交优化。结果表明,木薯淀粉经机械活化后,对微波功率、微波辐射时间、酯化剂用量、催化剂用量、淀粉含水量的依赖性明显降低,取代度和反应效率均为原木薯淀粉的2倍多。通过正交试验确定了制备柠檬酸酯淀粉的最佳工艺条件:微波功率800 W、微波辐射5.0 min、淀粉含水量35%、柠檬酸质量分数50%、氢氧化钠质量分数6%,所得产品的取代度为0.399 8,反应效率为88.84%。并采用红外光谱和X-射线衍射对木薯淀粉、活化淀粉及高取代度柠檬酸酯淀粉进行了表征。

Preparation of citrate starch with high degree of substitution using mechanical activation-assisted microwave irradiation method

Under the condition of microwave irradiation, using citric acid as esterification agent, sodium hydroxide as catalyst, the citrate starch was synthesized from cassava starch with different activation time. The effects of mechanical activation time, the microwave power, microwave irradiation time, water content, citric acid amount and sodium hydroxide amount on the esterification of cassava starch were investigated respectively by using the degree of substitute (DS) and the reaction efficiency (RE) of citrate starch as the evaluating parameter. And then, the best conditions of preparation technique are confirmed by anorthogonal test. The results indicated that the mechanical activation could decrease the dependent of microwave power, microwave irradiation time, water content, citric acid amount and sodium hydroxide amount, the DS and the RE of citrate starch activated for 60min are twice more than citrate starch for native cassava. The optimum conditions of citrate starch preparation were microwave high profile, 35% water content, 5.0 min microwave irradiation times, 50% citric acid content, 6% sodium hydroxide content, the DS of the products was 0.3998, and the RE was 88.84%. Furthermore, the structure of native starch, activated starch and high substituent citrate starch were further characterized by using fourier transform infrared (FTIR) and x-ray diffraction(XRD)