木薯羧甲基淀粉的机械活化固相化学法制备、表征及其特性

Preparation,Structural Characterization and Properties of Carboxymethyl Cassava Starch by Mechanical Activation-Assisted Solid-State Reaction

以木薯淀粉为原料,氯乙酸钠为醚化剂,氢氧化钠为催化剂,采用机械活化固相化学反应法制备羧甲基淀粉。以取代度为评价指标,通过单因素和正交试验设计优化确定最佳制备工艺,采用傅里叶红外光谱(Fourier transform infrared spectroscopy,FTIR)、X-射线衍射(X-ray diffraction,XRD)、扫描电镜(scanning electron microscope,SEM)对羧甲基淀粉的结构进行表征,并考察羧甲基淀粉的理化特性。结果表明,最佳工艺参数为淀粉与氯乙酸钠物质的量比1∶1、反应温度50℃、反应时间1.5 h、氢氧化钠溶液质量分数18.8%、搅拌速率380 r/min、球磨介质堆体积500 m L,在此条件下制备的羧甲基淀粉取代度为0.540 1。FTIR、XRD、SEM检测进一步证实木薯淀粉发生了羧甲基化反应。理化特性结果显示,羧甲基淀粉的黏度升高,溶解度增大,吸水性、保水性、冻融稳定性、抗酸碱性、抗酶解性等均得到较好的提高。

Carboxymethyl cassava starch was synthesized from cassava starch with monochloroacetate（MCA） as an etherifying agent and sodium hydroxide（Na OH） as a catalyst by mechanical activation-assisted solid-state reaction.Onefactor-at-a-time and orthogonal array design methods were used to optimize the preparation conditions for higher degree of substitution（DS）.The structure of carboxymethyl cassava starch was characterized by Fourier transform infrared spectroscopy（FTIR）,X-ray diffraction（XRD） and scanning electron microscope（SEM） and its physicochemical propertieswere systematically investigated.The optimal process parameters that provided maximum DS of 0.540 1 were obtained as follows： molar ratio of starch to sodium chloroacetate 1：1,reaction temperature 50 ℃,reaction time 1.5 h,sodium hydroxide concentration 18.8%,stirring speed 380 r/min,and volume of ball milling medium 500 m L.The etherification reaction of cassava starch was confirmed by FTIR,XRD and SEM.Results of the physicochemical properties showed that the solubility of carboxymethyl cassava starch and the viscosity of starch paste and were significantly increased; water-absorbing capacity,water-retaining capacity,freeze-thaw stability,and acid,alkali and enzyme resistance were also improved compared with the native starch.