低场核磁共振技术对香樟种子水分变化的研究

Analysis of internal moisture change of camphor seeds during drying by low field-NMR

利用低场核磁共振技术可以分析干燥过程中香樟种子的弛豫特性。采集弛豫衰减信号,使用同时逐次再现技术(SIRT)得到氢核的横向弛豫时间(T2)反演图谱,并对不同阶段的香樟种子内部水分的分布、转换以及含水率与核磁共振信号量之间的相关性进行了分析。结果表明:干燥过程中香樟种子的干燥速率随着干燥温度的升高而增加,香樟种子中存在3种不同状态的水,分别是结合水、不易流动水和自由水。在干燥过程中结合水的峰位变化不大,不易流动水和自由水的峰位均有起伏现象产生,干基含水率与其核磁共振信号量之间有较显著的线性关系,相关系数达到0.984 4。在干燥和存储过程中,可通过测试低场核磁共振信号量快速得出香樟种子的含水率。

A low field NMR(Nuclear Magnetic Resonance)technique was used to collect the transverse relaxation attenuation signal of camphor seeds at different drying temperatures.The transverse relaxation time of the hydrogen nucleus was obtained by SIRT(Simultaneous Iterative Reconstruction Technique)inversion,and the correlation between the moisture content of the dry base and the amplitude of the NMR signal was studied at different stages.The results showed that the water in camphor seeds was mainly distributed as strongly bound water,weakly bound water and free water.During the drying process,the peak position of the strongly bound water remained unchanged,but the peak positions of the weakly bound water and the free water fluctuated.The drying rate increasesd with the increase of the drying temperature.There was a very significant linear relationship between the total NMR signal amplitude and moisture content of drying base,and the correlation coefficient reached 0.984 4.