核磁共振及其成像技术在面团形成过程中的研究

Study on Industrial Dough Formation by Using NMR and MRI Technique

面团的形成是面制品生产过程中的重要工序，它的质量直接影响面制品的品质。核磁共振（Nuclear Magnetic Resonance，NMR）技术能直观、快速、精确地反映和体现面团在搅拌过程中水分迁移变化，通过磁共振成像（Magnetic Resonance Imaging，MRI）技术观察面团面筋网络的形成和破坏过程，采用多成分模型分析质子弛豫曲线，将面团中的水分划分为三部分，具有各自不同的自旋-自旋弛豫时间，分别为T21、T22和T23。随着和面时间的延长，面团的他值和质子信号幅度（A）发生相应的变化。研究结果发现，面团的NMR弛豫参数的变化规律，以及面团形成过程的所体现的MR图像对指导和评价工业化面团形成所需要的最佳搅拌时间具有重要意义。实验结果表明：当中速搅拌，水分添加量为面粉的45％，其水温为30℃时，低筋粉的和面时间为15～25min，其面团的质量最佳。

The formation of dough is a key tache in industrial flour processing and dough quality affects the quality of final products straightly. Nuclear Magnetic Resonence （NMR） technique can reflect the moisture movement in stir process quickly, intuitively and accurately. The moisture movement in dough during stir process was studied by using NMR, and the formation and destruction of the gluten net in dough was observed through the MRI （ Magnetic Resonance Imaging）images. In the NMR experiment, a multi -eomponent model was adopted to analyze the obtained proton relaxation curve, and according to the spin - spin relaxation time the water in the dough was divided into three parts, called T21 , T22, and T23 respectively. The value of T2 and the amplitude of proton signal change with the stir time extending. It is found that the change rule of NMR relaxation parameters and the MRI images are of great significance to evaluate the optimal stir time of industrial dough. The experimental result shows that the optimal stir time is 15 -25 rain for low gluten flour when stir with middle velocity and additive water is 45% of flour weight with temperature 30℃.