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Origin of suppressed demixing in casein/xanthan mixtures

van Gruijthuijsen, Kitty; Herle, Vishweshwara; Tuinier, Remco; Schurtenberger, Peter LU and Stradner, Anna LU (2012) In Soft Matter 8(5). p.1547-1555
Abstract
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... (More)
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. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Soft Matter
volume
8
issue
5
pages
1547 - 1555
publisher
Royal Society of Chemistry
external identifiers
  • wos:000298990600035
  • scopus:84855641703
ISSN
1744-6848
DOI
10.1039/c1sm06761c
language
English
LU publication?
yes
id
4861fc4f-869f-4683-9694-6ca06767d51e (old id 2362435)
date added to LUP
2012-02-23 14:51:21
date last changed
2017-10-08 04:07:58
@article{4861fc4f-869f-4683-9694-6ca06767d51e,
  abstract     = {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.},
  author       = {van Gruijthuijsen, Kitty and Herle, Vishweshwara and Tuinier, Remco and Schurtenberger, Peter and Stradner, Anna},
  issn         = {1744-6848},
  language     = {eng},
  number       = {5},
  pages        = {1547--1555},
  publisher    = {Royal Society of Chemistry},
  series       = {Soft Matter},
  title        = {Origin of suppressed demixing in casein/xanthan mixtures},
  url          = {http://dx.doi.org/10.1039/c1sm06761c},
  volume       = {8},
  year         = {2012},
}