Physicochemical Properties of Whey Protein-Stabilized Emulsions as affected by Heating and Ionic Strength

Authors

  • K. DEMETRIADES,

    1. The authors are affiliated with the Biopolymer & Colloids Research Laboratory, Dept. of Food Science, Univ. of Massachusetts, Amherst, MA 01003.
    Search for more papers by this author
  • J.N. COUPLAND,

    1. The authors are affiliated with the Biopolymer & Colloids Research Laboratory, Dept. of Food Science, Univ. of Massachusetts, Amherst, MA 01003.
    Search for more papers by this author
  • D.J. McCLEMENTS

    1. The authors are affiliated with the Biopolymer & Colloids Research Laboratory, Dept. of Food Science, Univ. of Massachusetts, Amherst, MA 01003.
    Search for more papers by this author

  • We thank the Massachusetts Agricultural Experiment Station (Project number MAS00745), Dairy Management Inc. and Nestle Research for support of this project.

ABSTRACT

Corn oil-in-water emulsions (19.6 wt%; d32∼ 0.6 μm) stabilized by 2 wt% whey protein isolate (WPI) were prepared with a range of pH (3–7) and salt concentrations (0–100 mM NaCl). These emulsions were heated between 30 and 90°C and their particle size distribution, rheological properties and susceptibility to creaming measured. Emulsions had a paste-like texture around the isoelectric point of WPI (∼φ 5) at all temperatures, but tended to remain fluid-like at pH >6 or <4. Heating caused flocculation in pH 7 emulsions between 70 and 80°C (especially at high salt concentrations), but had little effect on pH 3 emulsions. Flocculation increased emulsion viscosity and creaming. Results were interpreted in terms of colloidal interactions between droplets.

Ancillary