Rheological characterisation of ‘weak gel’ carrageenan stabilised milks

Abstract

The use of a controlled stress rheometer to characterise the rheology of weak gel behaviour of milk containing carrageenan is described. The interaction of carrageenan with the protein in milk produces a long-range network structure where the physical properties are dependent on the type of carrageenan used. With the use of a sensitive controlled stress rheometer, it was possible to characterise the rheological properties of these weak gels and differentiate between samples using both large deformation techniques, and small amplitude oscillatory measurements. Large deformation tests enabled the gels to be qualitatively compared based on an apparent yield stress, ‘structure point’, apparent shear viscosity and degree of hysteresis. Small amplitude oscillatory rheometry was applied to make comparisons from measurements that did not exceed the linear viscoelasticity of the system. Both the frequency and time dependence of the rheological properties were measured to characterise final gel properties and the kinetics of network development. Both large deformation rheology and small amplitude oscillatory rheology have been effective in providing quantitative and qualitative comparisons between the rheological properties of samples containing weak gel networks.