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Volume 158, 2012
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Structural changes of deposited casein micelles induced by membrane filtration

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Casein micelles undergo shape changes when subjected to frontal filtration forces. Grazing incidence small angle X-ray scattering (GISAXS) and atomic force microscopy (AFM) allow a quantification of such structural changes on filtration cakes deposited on smooth silicon micro-sieves. A trans-membrane pressure of Δp = 400 mbar across the micro-sieve leads to an immediate film formation after deposition of casein solution. We observe significant changes in the GISAXS pattern depending on how many layers are stacked on top of each other. Compared to a deposit formed by one layer, GISAXS on a deposit formed by three layers of casein micelles leads to less scattering in the vertical and more scattering in the horizontal direction. Simulations show that the experimental results can be interpreted by a structural transformation from an originally spherical micelle shape to an ellipsoidal-deformed shape. The results are supported by AFM measurements showing a reduced lateral size of casein micelles deposited on top of a membrane pore. The observed shape changes could be due to filtration forces acting on densely packed deposits confining the micelles into ellipsoidal shapes.

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Publication details

The article was received on 15 Feb 2012, accepted on 05 Apr 2012 and first published on 05 Apr 2012

Article type: Paper
DOI: 10.1039/C2FD20022H
Citation: Faraday Discuss., 2012,158, 77-88
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    Structural changes of deposited casein micelles induced by membrane filtration

    R. Gebhardt, T. Steinhauer, P. Meyer, J. Sterr, J. Perlich and U. Kulozik, Faraday Discuss., 2012, 158, 77
    DOI: 10.1039/C2FD20022H

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