Representative curves of shear stress versus shear rate
for blueberry pure´e at 25–60 1C and 10–25 Brix all indicate
shear-thinning behavior (Figs. 2(a)–(d)). The continuouscurves in these figures represent the Sisko model fitted to
the measured data. For the 0–1000 s1 shear rate
range investigated, the maximum shear stress imposed
on the blueberry pure´e at 251C increased from about
12 Pa for 10 Brix to almost 165 Pa for the 25 Brix. For all
the concentrations of solids investigated, there is
also evidence of finite yield stress (s0), which can be
estimated at flow conditions with the shear rate close to
zero (that is, as viscosity approaches infinity in the case a
shear-thinning fluid). The blueberry juices investigated
previously did not show any detectable yield stre