高取代度羧甲基小麦淀粉制备工艺的优化及表征

摘 要：以小麦淀粉为原料，以氯乙酸作为醚化剂，采用两次加碱法制备了高取代度的羧甲基小麦淀粉。以4.05g淀粉为基准，采用正交实验对反应条件进行了优化，得到的最佳工艺条件为：水用量6mL，无水乙醇用量60mL，氯乙酸与淀粉摩尔比1.4，氢氧化钠与氯乙酸摩尔比1.8，碱化用氢氧化钠百分比70%，碱化温度35～40℃，碱化时间0.5～1h，醚化温度50～55℃，醚化时间2～3h，在此条件下制得了取代度高达1.21的羧甲基小麦淀粉。

Synthesis process optimization and characterization of carboxymethyl wheat starch with high degree of substitution

Carboxymethyl wheat starch(CMHS) with high degree of substitution(DS) was synthesized from wheat starch with chloroacetic acid as the etherifying agent by twice alkalifying method.The process conditions were optimized by orthogonal experiment using 4.05 g of starch as the criterion,and the effects of water content,ethanol amount and etherification temperature on the DS of CMHS were investigated.The results indicated that the optimal process conditions were as follows: water content 6 mL,absolute ethyl alcohol 60 mL,molar ratio of chloroacetic acid to starch 1.4,molar ratio of sodium hydroxide to chloroacetic acid 1.8,mass fraction of sodium hydroxide 70%(for alkalization),alkalization temperature 35-40 ℃,alkalization time 0.5-1 h,etherification temperature 50-55 ℃ and etherification time 2-3 h,and CMHS with DS up to 1.21 was obtained under this synthetic conditions.Moreover,the product structure was characterized by FT-IR and XRD.