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The creep behavior of gels made using different concentrations of whey protein isolate (WPI, >95% protein) was systematically determined. The creep curves of these gels conformed to a six element mechanical model consisting of one Hookean, two Voigt and one Newtonian component. The concentration and temperature dependence of each viscoelastic constant were examined and the data are discussed in terms of mechanisms involved in gel network structure.

The creep behavior of gels prepared with lo-15% whey protein was measured at 15-75°C. Gels prepared with 12-15% protein were thermorheologically simple, although their action was not totally consistent with Williams-Landel-Ferry (WLF) criteria. Gels made with less than 11% protein were more sensitive to temperature than those containing more than 11% protein and their thermal viscoclastic action was not consistent with polymer theory. The apparent activation energy (AHa) of the gels decreased with increasing tempcraturcs and noncovalent forces were important in maintaining gel structures.

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