Rheological behaviour of sloe (Prunus spinosa) fruit juices

The rheological behaviour of sloe fruit juices with low pulp and pectins contents is studied. These juices, containing pectins and pulp, behave as non-Newtonian with a yield stress, so the Bingham model was used to describe the relationship between the shear stress and the shear rate. The effect of temperature on the plastic viscosity was examined, and it was concluded that an Arrhenius type equation describes this effect. The effect of soluble solids contents can be described by two types of equations, power-law and exponential expressions. Finally, an equation describing the combined effect of temperature and concentration on the plastic viscosity was developed.