Effect of filtration forces on the structure of casein micelles
Effect of filtration forces on the structure of casein micelles
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DOI：
10.1107/s1600576713029841
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发表时间：
2014-01-01
影响因子：
6.1
通讯作者：
Gebhardt, Ronald
中科院分区：
文献类型：
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作者：
Gebhardt, Ronald
压力驱动膜过滤是一种广泛使用的从牛奶中的较小成分中分离酪蛋白胶束(CM)的方法。研究了附着在膜上的CM的结构，因为在这种沉积状态下，它们会降低过滤过程的性能。采用纳米和微米级X射线束和以硅微筛为膜的过滤装置进行了散射实验。掠入射小角X射线散射(GISAXS)实验表明，球形CM在过滤流动方向上发生了拉伸。从二维GISAXS图像中提取的一维散射函数用单一椭球形状因子拟合进行了分析。根据该模型，在跨膜压力为p=400mbar(1mbar=100Pa.)时，CM呈椭圆形。随着跨膜压力的增加，CM的形状在400到600毫巴之间经历了向扁平结构的转变。用200 nm光束进行的小角X射线散射实验允许在微筛的单个孔中对CM进行传输实验。在滤力作用下的CM的散射函数中不能确定其内部结构的典型特征。
Pressure-driven membrane filtration is a widely used method to separate casein micelles (CM) from smaller components in milk. The structure of CM attached on the membrane has been investigated because in such a deposited state they reduce the performance of the filtration process. Scattering experiments with nano-and micrometre sized X-ray beams and a filtration setup with silicon micro-sieves as membranes were used. Grazing-incidence small-angle X-ray scattering (GISAXS) experiments above porous regions of the micro-sieves show that spherical CM become stretched in the direction of the filtration flow. The one-dimensional scattering functions extracted from the two-dimensional GISAXS patterns were analyzed by a single ellipsoidal form factor fit. According to the model, CM assume a prolate ellipsoidal shape at a transmembrane pressure of Delta p = 400 mbar (1 mbar = 100 Pa). With increasing transmembrane pressure, the shape of the CM undergoes a transition towards an oblate structure between 400 and 600 mbar. Small-angle X-ray scattering experiments with a 200 nm beam allow for transmission experiments on CM in a single pore of the micro-sieve. Typical characteristics of the internal structure could not be identified in the scattering functions of CM subjected to filtration forces.