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

Flow characteristics and rheological parameters of “Malas Yazdi” pomegranate (Punica granatum L.) juice were investigated using rotational viscometer at different temperatures (۱۰, ۲۰, ۳۰, ۴۰, ۵۰, ۶۰ and ۷۰ºC) and concentrations (۱۲, ۲۲, ۳۲, ۴۲ and ۵۲º Brix). The experimental data had the best fitness with Herschel-Bulkley model and the values of flow behavior index (n) varied between ۰.۹۷ and ۱.۴۵ 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 ۴۰ rpm increased from ۹.۰۷ to ۲۴.۰۵ kJ mol-۱ as the juice concentration increased from ۱۲ to ۵۲º 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