大米直链淀粉分子量分布及分子旋转半径的研究

Analysis of molecular weight distribution and root mean square radius of amylose from rice starch

为了从大米淀粉中有效的分离出直链淀粉,建立直链淀粉分子量的分析方法,从而得出确切的大米直链淀粉分子结构方面的信息,通过使用流变仪控制大米淀粉的升温糊化过程,用浸出法在不同温度下分离出大米直链淀粉,利用高效液相分子排阻色谱（HPSEC）与多角度光散射仪（MALLS）及折光检测器（RI）连用系统,分析了大米直链淀粉的分子量分布和分子旋转半径。得到不同品种的大米淀粉中分离出的直链淀粉的重均分子量范围为3.29×10^5～2.75×10^6。研究表明,90℃以上高温不利于用浸出法从直链淀粉含量低的大米淀粉中分离直链淀粉,当温度低于90℃而高于糊化温度时,各个温度下均可用浸出法分离出直链淀粉,得到的直链淀粉具有十分相似的分子量分布、重均分子量和分子旋转半径。该方法是一种简便、快速的分离大米直链淀粉,并测定其分子量的方法,具有较高的准确性。

The amylose was separated from rice starch and the method for analyzing the molecular weight distribution of amylose was set up in order to obtain the structure information of amylose from rice starch. Aqueous leaching of amylose from rice starch was carried out in order to analyze the molecular weight distribution and root mean square radius of amylose from rice starch. The amylose leached out at different temperatures during pasting was controlled by a rotational rheometer. The molecular structure of amylose from rice starch was analyzed by a HPSEC-MALLS-RI system. The range of Mw values of amylose from different types of rice starch is from 3.29 ×10^5～2.75×10^6. There are no significant differences in the molecular weight distribution, Mw and RMS of the amylose leaches out at the temperature between the onset pasting temperature and 90℃. The method developed in our study is convenient and easy to control.