羟乙基籼米淀粉的制备及结构特征

摘要

使用籼米淀粉作为原材料,采用溶媒法结合超声波处理原淀粉以氯乙醇作为醚化剂制备羟乙基籼米淀粉.通过单因素实验优化合成条件,并用FTIR、XRD、SEM和TG-DSC对产品进行结构特征分析.结果表明,在籼米淀粉10.0 g,蒸馏水30 mL时,优化合成的条件如下:温度50℃,氢氧化钠2.4g,无水乙醇50mL,氯乙醇4 g,反应时间8h.X射线衍射和扫描电镜分析表明籼米淀粉的醚化反应主要发生在非结晶区,醚化作用没有改变淀粉结晶区的晶型;籼米淀粉经过超声波处理和醚化后,其晶型结构与颗粒形貌均受到破坏.对比原淀粉和羟乙基籼米淀粉的红外光谱说明籼米淀粉确实发生了羟乙基化.热稳定性分析证明籼米淀粉经过羟乙基化后,其水分蒸发温度和融熔温度均降低.超声波处理有助于羟乙基淀粉的合成及破坏原淀粉的晶型结构.%Using indica rice starch as raw material,hydroxyethyl indica rice starch was prepared by chloroethanol as etherifying agent through solvent method combined with ultrasonic treatment of starch.Through the single factor experiment,synthesis conditions of hydroxyethyl indica rice starch were optimized.And structure features of hydroxyethyl indica rice starch were analyzed by FTIR,XRD,SEM and TG-DSC,respectively.The results showed that under the basic conditions of the milled starch 10.0 g and distilled water 30 mL,the optimun conditions include temperature of 50 ℃,sodium hydroxide of 2.4 g,chloride anhydrous ethanol of 50 mL,ethanol of 4 g and reaction time of 8 h.X-ray diffraction and scanning electron microscope analysis indicated that the etherification reaction of indica rice starch mainly occurs in the amorphous region,and the etherification reaction fails to change the crystal shape of crystallization area of starch.After ultrasonic treatment and etherificating,the crystal structure and morphology of the particles of indica rice starch were destroyed.Comparison on the infrared spectrum of original starch and hydroxyethyl indica rice starch,hydroxyethylation occurs in the indica rice starch molecules.The thermal stability analysis proved that water evaporation temperature and melting temperature of indica rice starch were decreased after hydroxyethylation.Ultrasonic treatment contributes to the synthesis of hydroxyethyl starch and destruction of the original starch crystal structure.