Abstract:
Flow characteristics and rheological parameters of “Malas Yazdi” pomegranate
(Punica granatum L.) juice were investigated using rotational viscometer at different
temperatures (10, 20, 30, 40, 50, 60 and 70ºC) and concentrations (12, 22, 32, 42 and 52º
Brix). The experimental data had the best fitness with Herschel-Bulkley model and the
values of flow behavior index (n) varied between 0.97 and 1.45 at all temperatures and
concentrations, revealing the shear thickening nature of pomegranate juice. The
activation energy of flow (Ea
) calculated with respect to apparent viscosity at 40 rpm
increased from 9.07 to 24.05 kJ mol-1 as the juice concentration increased from 12 to 52º
Brix. Power equation indicated that consistency coefficient increased non-linearly with
concentration increase. A mathematical model was developed to describe the influence of
temperature and soluble solids on the consistency coefficient of pomegranate juice for the
studied conditions.
Keywords: Apparent viscosity, Consistency coefficient, Pseudoplastic, Shear-thickening.
