Rheological characterization of semisolid dairy desserts. Effect of temperature

The rheological behaviour of seven samples of commercial Spanish dairy dessert 'natillas' were studied by both static and dynamic methods and the influence of the usual consumption temperatures (5 and 25 °C) on both their flow and their viscoelastic properties was analysed. All samples exhibited typical shear thinning behaviour, the flow curves fitting well to the Carreau model. As expected, data obtained at 25 °C followed the same pattern but with lower apparent viscosity values than those at 5 °C. The mechanical spectra obtained for most samples was typical of gelled materials, at both temperatures, with G′ higher than G″, both moduli showing little variation with frequency. All samples showed increasing tanδ values with frequency, indicating a higher contribution of the viscous component at higher frequencies. The differences in rheological behaviour between samples, obtained by static shear and by oscillatory shear measurements, were highly coincident.