Journal article

Origin of suppressed demixing in casein/xanthan mixtures

  • Gruijthuijsen, Kitty van Adolphe Merkle Institute, University of Fribourg, Switzerland
  • Herle, Vishweshwara Department of Physics, University of Fribourg, Switzerland - BASF, Ludwigshafen, Germany
  • Tuinier, Remco Van 't Hoff Laboratory for Physical and Colloid Chemistry, University of Utrecht, The Netherlands
  • Schurtenberger, Peter Division of Physical Chemistry, University of Lund, Sweden
  • Stradner, Anna Division of Physical Chemistry, University of Lund, Sweden
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  • Soft Matter. - 2012, vol. 8, no. 5, p. 1547-1555
English We explore the properties of casein/xanthan mixtures for xanthan concentrations beyond those inducing phase separation. Previous work has successfully described the onset of demixing by depletion theory in the protein limit, where the xanthan polysaccharides , the polymers , are larger than the caseins from skim milk powder, the colloids (S. Bhat et al., J. Phys.: Condens. Matter, 2006, L339). We now extend these studies to xanthan concentrations in a range of c/c* = 13–88, aiming to arrest the phase separation via a (transiently) arrested casein-rich phase. Surprisingly, we find that the casein-rich phase remains fluidic deep into the two-phase region, with an equilibrium composition that significantly differs from predictions for mixtures of hard spheres plus flexible polymer chains in a good solvent . Furthermore, we show that macroscopic phase separation is arrested for c/c* > 60. Our investigations reveal that the rheological properties of the mixtures are fully determined by the xanthan-rich phase with characteristic long relaxation times that depend remarkably strongly on the xanthan concentration.
Faculté des sciences et de médecine
Département de Physique
  • English
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