酰胺化凉粉草胶制备工艺及其性质的研究

Study of Amidated Mesona Blumes Gum Preparation and Its Properties

以凉粉草胶为原料,对其进行酰胺化处理。以氨水-异丙醇为反应介质,通过酰胺化反应和酸醇沉淀技术对凉粉草胶进行分子修饰,并以果胶的酯化度(DE值)、酰胺取代度(DA值)等指标作为考察依据。经过单因素和正交试验,最后确定酰胺化凉粉草胶的最佳制备工艺为:15%的凉粉草胶;酰胺化反应时间120min;氨水浓度5mol/L;氨水:异丙醇=1:2;氨醇溶液:凉粉草胶=4:5。通过红外光谱测定和扫描电子显微镜分析,进一步表明凉粉草胶在经过酰胺化反应后,颗粒形貌和内部结构发生了明显的变化。对酰胺化凉粉草胶的凝胶强度和原胶的凝胶强度进行对比,结果发现由酰胺化凉粉草胶制备的果冻的凝胶强度比原草胶的弱,这可能是由于酰胺化凉粉草胶与大米淀粉之间形成的空间网状结构的相互作用力较原草胶弱。

Mesona Blumes gum （MBG） was taken as raw material to be amidated. By using ammonia- isopropanol reaction media, MBG was modified at molecular level through amidation and acid-alcohol precipitating, which took esterification degree （DE）, amide substitution degree （DA） as a result of reaction. Through single experiment and orthogonal experiments, the optimal preparation process condition was determined like following： 15% MBG, 120 min amidation time, 5 mol/L ammonia concentration, 1/2 ammonia/isopropanol, 4/5 ammonia alcohol solution/MBG. Then by using FTIR determination and SEM analysis, it was further shown that granular morphology and inner structure of MBG had changed obviously after arnidation. And finally there was a gel strength comparison between gels made of amidated MBG and raw MBG respectively. It was found that the gel made of amidated MBG was weaker than that made of MBG, which indicated that amidated MBG might form a weaker network with rice starch than MBG did.