Dresden 2009 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 37: Biopolymers (joint session CPP/BP)
CPP 37.10: Vortrag
Donnerstag, 26. März 2009, 17:00–17:15, ZEU 114
Hydration behavior of casein micelles in thin film geometry: A GISANS study — •Ezzeldin Metwalli1, Jean-Francois Moulin2, Ronald Gebhardt3, Robert Cubitt4, Alexander Tolkach5, Ulrich Kulozik5, and Peter Müller-Buschbaum1 — 1TU München, Physik Department LS E13, James-Franck-Str.1, 85747 Garching, Germany — 2FRM II, TU München, 85747 Garching, Germany — 3ESRF, b.p. 220, 38043 Grenoble, France — 4ILL, 6 rue Jules Horowitz, b.p. 156, 38042 Grenoble, France — 5TU München, Chair for Food Process Engineering and Dairy Technology, 85354 Freising-Weihnstephan, Germany
The water content of the casein micelle films in water vapor atmosphere is investigated using time-resolved grazing incidence small-angle neutron scattering (GISANS). Initial dry casein films are prepared with spin coating method. At 30 °C the formation of a water equilibrated casein protein film is reached after 11 min with a total content of 0.36 g water/ g protein. With increasing water vapor temperature up to 70 °C an increase in the water content is found. With GISANS, lateral structures in the nano-meter scale are resolved during the swelling experiment at different temperatures and modeled using two spheres named micelles and mini-micelles. Upon water uptake, molecular assemblies in the size range of 15 nm (mini-micelle) is attributed to the formation of high contrast D2O outer shell on the small objects that already exist in the protein film [1]. These results are discussed and compared with various proposed models on the casein micelle structures. [1] E. Metwalli et al., Langmuir accepted 2008.