应用低场核磁共振研究绿豆浸泡过程

Study of Water Absorption of Mung Beans Based on Low-field Nuclear Magnetic Resonance Technology

本实验采用低场核磁共振技术对绿豆浸泡过程进行研究,目的是从一种新的角度来解释绿豆种子内部吸水的动态过程,通过把绿豆浸泡入水中,每隔0.5h分别测量其脉冲FID信号、弛豫时间T2,每隔1h进行核磁共振成像。实验结果表明:绿豆吸水率在浸泡3h后进入迅速增长,至5.5h后吸水率变化缓慢;绿豆吸入水分可分为三种状态水:毛细管水T21、自由水T22以及结合水T23;毛细管水T21随时间变化为波浪型,自由水T22以及结合水T23变化基本一致,为稳定-上升-稳定;自由水作为溶剂在绿豆吸水过程中参与各种生化反应,故自由水的质子密度(信号量)上升量最大。从核磁共振图像中可以看到水是从种脐处慢慢进入绿豆内。低场核磁共振技术同样可应用于其他种子浸泡过程分析。

Low field （0.01 to 0.5 Tesla） nuclear magnetic resonance （NMR） instrument has spread out its applications in many fields such as food manufacture, petroleum industry,agriculture, matireal research and so on because of its low cost and easy maintenance. For the purpose of explaining the dynamic water absorbing process of mung beans from a new point of view, lowfield NMR technology was adopted in this study. Mung beans were immersed in watre and taken out every 0.5 hfor the testing of FID signal and T2 relaxation time and every 1 h for the NMR imaging. The water absorption of mung beans has a quick rise after 3 hours and enters into a stable period after 5.5 hours. There are three states of water in the mung beans including capillary water T21, free water T22 and bound water T23. Capillary water T21 exhibited a wave-like movements change and free water T22 and bound water T23 had a similar change： stable-rising-stable. Free water as a good solvent participates in different types of biochemical reaction and therefore the increase of proton density value （signal value） of free water was the biggest. The NRM images showed that the watrer absorbing of mung bean was started hilum. Our study results prove that low-field NMR technology also can be applied in the studies of seed immersion of other grains.