南酸枣糕烘干过程中水分的迁移和分布

Characterization of water mobility and distribution in choerospondias axillaris pastilles during dry by nuclear magnetic resonance

利用核磁共振及其成像技术,探究南酸枣糕在烘干过程中水分含量、迁移和分布情况。通过分析南酸枣糕烘干过程中核磁共振的自由衰减弛豫时间、自旋-自旋弛豫时间和核磁共振成像图发现:南酸枣糕的水分含量与体系的质子密度高度线性相关,其相关系数达到0.990 6。因此,可以通过建立水分含量与核磁共振质子密度的标准曲线实现南酸枣糕水分含量的核磁共振定量测定;在烘干过程中,随着时间的延长,南酸枣糕中的束缚水的流动性(T21)呈降低的趋势,自由水的流动性(T22)呈先增加后降低的趋势,核磁共振成像图逐渐变暗;从成像图也可直观地看出,南酸枣糕内部弛豫信号比外部强,证实南酸枣糕干燥是一个不均匀的干燥过程。

The moisture state, distribution and migration process of choerospondias axillaris pastilles during drying was investigated by using nuclear magnetic resonance （NMR） and magnetic resonance imaging （MRI） techniques. Experiment was carried out through the analysis of free relaxation time, spin spin relaxation time of NMR and the images of MRI during the drying process. The results showed a linear relationship between moisture content of choerospondias axillaris pastilles and proton density of system with R2 reaching 0. 990 6, therefore, moisture content can he measured with NMR by establishing a standard curve of moisture content and proton density, there two kinds of water state of choerospondias axillaris pastilles： bound water and free water, The bound water of choerospondias axillaris pastilles was gradually reduced with the extended of drying time, while the free water mobility increase first and decreased later in the drying process. As a result, the image was gradually darkened in the MRI. The internal relaxation signal of ehoerospondias axillaris pastilles stronger than external re laxation signal, which proved that the drying process of choerospondias axillaris was a non-uniform drying process.