乙酰化柠檬酸酯化交联机械活化淀粉的制备及性质分析

Preparation of Acetylated Citric Acid Esterified and Cross-linked Mechanically Activated Starch and the Analysis of Their Properties

以机械活化木薯淀粉为原料,醋酸酐为酯化剂,柠檬酸为交联剂,采用溶剂法制备乙酰化柠檬酸酯化交联淀粉,考察了机械活化时间、混合酸添加量、反应温度、反应时间、柠檬酸与乙酸酐质量比等因素对乙酰化柠檬酸酯化交联淀粉沉降积的影响,并对制备得到的酯化交联淀粉进行结构表征及性质测定。结果表明,制备最佳工艺条件为:机械活化时间40min、混合酸添加量(占淀粉干重)10%、反应温度45℃、反应时间1 h、柠檬酸与乙酸酐质量比1:35,所得产品沉降积为1.52 m L。FT-IR表明淀粉被成功酯化交联,XRD表明酯化交联主要发生在淀粉的非结晶区。性质测定表明,析水率、糊透明度均为:机械活化淀粉>原淀粉>酯化交联机械活化淀粉>酯化交联淀粉,说明酯化交联淀粉冻融稳定性较好,糊透明度较低;抗酸性:酯化交联机械活化淀粉>机械活化淀粉>酯化交联淀粉>原淀粉,表明机械活化处理能提高淀粉的抗酸性;酯化交联淀粉的黏度热稳定性优于淀粉。综合比较,机械活化酯化交联淀粉具有更好的冻融稳定性、抗酸性和黏度热稳定性。

Acetylated citric acid esterified and cross-linked starch was prepared by the solvent method,with mechanically activated cassava starch as material,acetic anhydride as esterification agent,and citric acid as cross-linking agent.The effects of mechanical activation time,amount of mixed acids,reaction temperature,reaction time,and mass ratio of citric acid to acetic anhydride on the sedimentation volume of acetylated citric acid esterified and cross-linked starch were investigated.The structure and properties of the as-prepared esterified and cross-linked starch were characterized and determined.The results showed that the optimum technological conditions were as follows:mechanical activation time of 40 min,addition amount of mixed acid of 10%(accounting for dry weight of starch),reaction temperature of 45℃,reaction time of 1 h,and the mass ratio of citric acid to acetic anhydride of 1:35,the sedimentation of product was 1.52 ml.FT-IR showed that the starch was successfully esterified and cross-linked.X-ray diffraction(XRD)showed that the esterification and cross-linking reactions occurred in the amorphous region of starch.The results showed that the order of water extraction rate and paste transparency is as follows:mechanical activated starch>raw starch>esterified and cross-linked mechanically activated starch>esterified and cross-linked starch,which indicates a better freeze-thaw stability and a lower paste transparency of esterified and cross-linked starch compared to those of raw starch.In addition,the order of acid-resistance properties is as follows:esterified and cross-linked mechanically activated starch>mechanically activated starch>esterified and cross-linked starch>original starch,indicating that mechanical activation can improve the acid-resistance property of starch.Furthermore,the viscosity thermal stability of esterified and cross-linked starch is better than that of raw starch.In general,the mechanical activated esterification cross-linked starch displays a better freeze-thaw stability,acid-resistance property and viscosity thermal stability.