Modeling of Rheological Characteristics of “MalasYazdi” (Punicia granatum L.) Pomegranate Juice

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.