Rheological characterisation of 'weak gel' carrageenan stabilised milks

The use of a controlled stress rheometer to characterise the rheology of we ak gel behaviour of milk containing carrageenan is described. The interacti on of carrageenan with the protein in milk produces a long-range network st ructure where the physical properties are dependent on the type of carragee nan used. With the use of a sensitive controlled stress rheometer, it was p ossible to characterise the rheological properties of these weak gels and d ifferentiate between samples using both large deformation techniques, and s mall amplitude oscillatory measurements. Large deformation tests enabled th e gels to be qualitatively compared based on an apparent yield stress, 'str ucture point', apparent shear viscosity and degree of hysteresis. Small amp litude oscillatory rheometry was applied to make comparisons from measureme nts that did not exceed the linear viscoelasticity of the system. Both the frequency and time dependence of the rheological properties were measured t o 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 b etween the rheological properties of samples containing weak gel networks. (C) 2000 Published by Elsevier Science Ltd.