Physicochemical and Rheological Behavior of African Star Apple (Chrysophyllum Albidium) Juice as Affected by Concentration and Temperature Variation

The viscosity, shear stress and shear rate of African star apple juice (Chrysophyllum albidium) at different concentrations of 8 % to 32% total solid concentration and temperature range of 20°C to 70°C were obtained in order to determine the effect of changes in concentration and temperature on the rheological properties of the juice. Also, the physico-chemical analyses of the sample were carried out. Plot of shear stress against shear rate showed that at all concentrations, African star apple juice behaved as a non-Newtonian fluid at temperature below 60°C. At 70°C, however, lower concentration (8% and 12%) behaves non-Newtonian while higher concentrations behave Newtonian. Increase temperature decreases the viscosity of the juice. The knowledge of rheological properties of African star apple juice is essential for the design and optimization of energy process and heat transfer.

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