VISCOUS BEHAVIOR OF WHEY-PROTEIN CONCENTRATE DISPERSIONS

The viscosity and gelling tendency of concentrated whey protein dispersions (11 or 20%, w/nu, protein), prepared from several whey protein concentrate (WPC) powders, were studied as a function of pH, time and added calcium. From about pH 6.8 to 4.0, at 20 degrees C, all WPC dispersions had relatively low apparent viscosities with negligible variation, bud below pH 4.0, sharp and substantial increases in apparent viscosity occurred, especially at 20% (w/nu) protein, in the presence of added calcium ol on standing of dispersions over lime. At pH 3.0, WPC dispersions containing 20% (w/nu) protein formed semi-solid gel-like structures. Thermal treatment (85 degrees C for 30 min) of the acidic, viscous WPC dispersions (11%, w/nu, protein) induced the formation of relatively strong gels, especially at pH 4.0, while at pH 3.0 the gels were weaker, but still much stronger than without heat treatment.