Protein-polysaccharide interactions: The determination of the osmotic second virial coefficients in aqueous solutions of ß-lactoglobulin and dextran

H.M. Schaink, J.A.M. Smit

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16 Citations (Scopus)

Abstract

Solutions containing dextran and solutions containing mixtures of dextran +ß-lactoglobulin are studied by membrane osmometry. The low concentration range of these solutions is considered. From the measured osmotic pressures the virial coefficients are obtained. These are analyzed using the osmotic virial coefficient of ß-lactoglobulin solutions published earlier by us [Schaink, H.M., & Smit, J. A.M. (2000). Determination of the osmotic second virial coefficient and the dimerization of beta-lactoglobulin in aqueous solutions with added salt at the isoelectric point. PCCP, 2, 1537¿1541]. The second cross-virial coefficient A12 is found to be positive indicating a repulsive and probably mainly steric interaction between neutral in nature dextran and and practically uncharged ß-lactoglobulin (pH=5.18). The measurements show that the ß-lactoglobulin has only a small tendency to form multimers in the presence of dextran. The phase diagram of solutions of dextran+Whey Protein Isolate (appr. 60% ß-lactoglobulin) is also presented. The McMillan¿Mayer equation of state that considers only the second virial coefficients is found to be unreliable for the extrapolation up to the concentrations at which phase separation is expected Keywords: Proteins; Polysaccharides; Osmotic pressure; Virial coefficients; Phase separation
Original languageEnglish
Pages (from-to)1389-1396
JournalFood Hydrocolloids
Volume21
Issue number8
DOIs
Publication statusPublished - 2007

Keywords

  • bovine serum-albumin
  • phase-separation
  • depletion
  • mixtures
  • pressure
  • lysozyme
  • systems
  • model
  • size
  • dimerization

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