机械活化木薯淀粉制备低取代度醋酸酯淀粉的研究

摘要

The cassava starch acetate of low degree of substitution were preparation using mechanical activated cassava starch which was mechanical activated for half an hour and the native starch as material acetic anhydride as acetylation reagent and sodium hydroxide as catalyst. The effects of reaction temperature, the reaction time, acetic anhydride amount and pH value on esterification of cassava starch were investigated respectively by using degree of substitution (DS) and reaction efficiency (RE)of starch acetate as evaluating parameter. The results showed that reaction temperature, the reaction time, acetic anhydride amount and pH value had certain effect on the DS and the RE of starch acetate. Mechanical activation can significantly increase the DS and the RE of starch acetate. The optimal technical conditions were obtained as reaction temperature 30℃, reaction time 40 minutes, acetic anhydride amount 0.15 mL, pH value 8.5. Under the conditions, the DS in the products was 0.075, and the RE was 87.45 %. Furthermore, the structure of activated starch and the starch acetate were further characterized by using FTIR.%以机械活化0.5 h的木薯淀粉和木薯原淀粉为原料，以醋酸酐为酯化试剂，氢氧化钠为催化剂，制备低取代度木薯淀粉醋酸酯。以淀粉醋酸酯的取代度和反应效率为评价指标，分别研究反应温度、反应时间、醋酸酐用量、pH各因素对其取代度和反应效率的影响。实验结果表明，反应温度、反应时间、醋酸酐用量、pH对木薯淀粉醋酸酯的取代度和反应效率均有影响。机械活化能显著提高木薯淀粉醋酸酯化反应的取代度和反应效率。通过试验得到制备低取代度木薯淀粉醋酸酯的较佳工艺条件为：反应温度为30℃，反应时间为40 min，醋酸酐用量为0.15 mL，pH为8.5时，在此条件下制备的醋酸酯淀粉的取代度为0.075、反应效率为87.45%。并用红外光谱对醋酸酯淀粉进行分析。