醋酸酐制备低取代度木薯淀粉醋酸酯

Preparation for cassava starch acetate with low degree of substitution by acetic anhydride

目的以木薯淀粉为原料,醋酸酐为乙酰化试剂,NaOH为催化剂,Na2SO4为膨胀抑制剂,制备了低取代度木薯淀粉醋酸酯。方法考察反应温度、反应时间、木薯淀粉浓度等因素对醋酸酯淀粉乙酰基含量的影响。结果通过均匀设计实验得到了合成低取代度醋酸酯淀粉的最佳工艺条件:反应温度21℃,反应时间120min,木薯淀粉浓度45%,Na2SO4用量2%,醋酸酐用量6%(以淀粉干基质量计),得到的产物乙酰基含量1.68%,取代度(DS)0.0643。结论控制适当的反应条件,产品的凝沉性、透明度和粘度等理化性质有了显著的提高。

Aim To prepare lower degree of substituted starch acetate with cassava starch as material, acetic anhydride as acetylation reagent, sodium hydroxide as catalyst and sodium sulfate as gelatinization inhibiter. Methods The effects of reaction factors such as reaction temperature, reaction time and the concentration of cassava starch on acetyl content of cassava acetate starch were studied. Results The optimum conditions for lower substituted synthetic acetate starch, which was obtained by uniform experimental design, were as follows： reaction temperature was 21 ℃ ; reaction time was 120 min; pH=8.0-8.4; the amount of sodium sulfate was 2%; the concentration of cassava starch was 45% and the amount of acetic anhydride was 6% （calculated by the dry weight of starch）. Under the conditions, the content of acetyl in the products was 1.68%, and the degree of substitution （DS） was 0. 064 3. Conclusion The physicochemieal properties of products such as retro-gradation, transparence and viscosity were improved under proper reaction conditions.