杜伦麦在不同制粉条件下破碎模式的研究

选用了不同的磨辊速比以及不同的杜伦麦入磨水分进行磨碎实验 .麦粒经过一皮磨辊磨碎后 ,选出大的麦渣用电子扫描显微镜来观察破碎情况 .电子扫描显微镜图像表明 :在高速比下麦粒的破裂呈现出又大又长的裂沟 ,而且裂沟从麦粒中部一直沿长到糊粉层 .在低速比下麦粒的破裂呈现出细小而且很短的裂纹 ,但是裂纹的数量很多 .在低速比较强的挤压作用下 ,不但产生了断面上的淀粉破损 ,而且增加了麦渣内部的淀粉破损 .当麦粒水分增加时 ,破碎表面显得粗糙不平 .当麦粒水分降低时 ,破碎呈现光锐棱角而且断裂表面整齐平滑 .由于水分是沿着细胞壁传播的 ,高水分削弱了细胞壁与细胞质之间的结合力 ,从而导致了更多的细胞内部的分离断裂 .高水分同时也削弱了淀粉颗粒与蛋白网络之间的结合力 ,因而麦粒在高水分条件下破碎时 ,淀粉破损降低 .

EVALUATION OF FARACTURE IN DURUM WHEAT KERNELS RESUL TING FROM DIFFERENT MILLING CONDITIONS

A durum wheat variety (Renville) was milled at selected differentials and at selected wheat moisture contents.The resulting coarse particles were examined by Scanning Electron Microscopy(SEM).The SEM pictures revealed that fractures resulting from a high speed differential of the rolls appeared larger and longer and stretched into the region of aleurone cells.Fractures resulting from a lower speed differential were smaller,shorter and more numerous.The greater compression effect of the lower speed differential probably resulted in starch damage that occurred on the surface and within the particles.Cut surfaces of the coarse particles were projected as jagged at high wheat moisture content,but were sharp and clena at lower moisture content.High moisture appeared to weaken the bond between the starch endosperm cell walls and the cell contents,which resulted in more inter-cellular fractures.Higher moisture also seem to weaken the bond between the protein matrix and the starch granules and,consequently,reduced the level of starch damage.