Rheological Properties of Date Juice, Pomegranate Juice and their Concentrates: A Review

This review aims to investigate the rheological properties of date juice, pomegranate juice and their concentrates and to identify their flow behaviour. There are many rheological properties that have been studied, including viscosity, coefficient of flow behaviour index, type, and cohesion coefficient. Knowing the rheological properties of date juice and pomegranate and their concentrates is of paramount importance in various food processing operations. The flow behaviour index, activation energy and cohesion coefficient of date and pomegranate juices ranged between 0.605–0.988 and 0.776–1.45 J/mol, 1.9*104–3.3*104 and 32200–54430, 0.002–0.102 and 0.0013-0.075 Pa.sn, respectively. Both date juice and pomegranate juice with their distinct concentrations, have a non-Newtonian, semi-plastic behaviour that varies according to the type and variety of the fruit. There are several models have been used to describe the flow behaviour of date and pomegranate juices. The most important factors that affect the rheological properties and flow behaviour of the date and pomegranate juices are the temperature and the concentration of dissolved solids in the juice. Arrhenius equation is used to express the effect of temperature on the rheological properties of date and pomegranate juice and their various concentrates. Also, the apparent viscosity increases with rising concentration of dissolved solids and decreasing temperature. KEYWORDS Date juice, pomegranate juice, rheological properties, flow behaviour, cohesion coefficient