高取代度羧甲基玉米淀粉制备工艺的研究

Study on preparation of highly substituted carboxymethyl corn starch

以玉米淀粉为原料,乙醇为溶剂,氯乙酸为醚化剂,研究高取代度羧甲基淀粉的制备工艺。还比较了不同淀粉、醚化剂的种类以及Na OH状态对取代度的影响。结果表明,最佳工艺为:二次加碱法,95%(质量分数)的乙醇作溶剂,淀粉乳浓度为25%,氯乙酸用量为115 g,Na OH用量为2.25(摩尔比,碱∶酸),碱化温度为40℃,碱化时间为10 h,碱化Na OH用量为1(摩尔比,碱∶酸),醚化温度为40℃,醚化时间为10 h,醚化阶段用14 g Na_2CO_3代替部分Na OH。一步法制备了取代度(DS)=1.21,反应效率(RE)=61.38%的羧甲基淀粉(CMS),非晶颗粒态淀粉的取代度比原淀粉略高,四种淀粉制备CMS取代度从高到低依次为马铃薯淀粉、木薯淀粉、蜡质玉米淀粉、玉米淀粉,氯乙酸作醚化剂时取代度远高于氯乙酸钠,固体碱制备CMS的取代度比液体碱高。

This paper mainly used corn starch as raw material,ethanol as solvent,chloroacetic acid as etherification agent,to study the influence of various factors on the degree of substitution（DS） respectively. The processing conditions of preparing carboxymethyl starch（CMS） with high degree of substitution was as follows ：sodium hydroxide was added for two times,95%（mass fraction） ethanol as solvent,starch slurry concentration was25 %, 115 g chloroacetic acid, dosage of sodium hydroxide was 2. 25（ molar ratio, alkali ： acid）, 40 ℃ was adopted to alkalify starch,alkalization for 10 h,sodium hydroxide for alkalization was 1（molar ratio,alkali∶acid）,40 ℃ was used to etherify starch,kept the etherification for 10 h,14 g sodium carbonate was used to replace part of sodium hydroxide during etherification phase. In addition,comparison of effects on DS of different types of starches,etherifying agents and sodium hydroxide states were also had been discussed. Results showed that the carboxymethyl starch,which DS was 1.21 and reaction efficiency（RE） was 61.38%,was attained by one step method. DS of non-crystal granular starch was slightly improved compared with native starch.According to DS from high to low,it was potato starch,cassava starch,waxy corn starch,corn starch successively that were used to prepare CMS. DS of CMS based on chloroacetic acid as etherification agent was much higher than sodium chloroacetate,and DS of CMS prepared by solid alkali increased dramatically compared with liquid alkali.