Journal of Food Processing & Technology

Abstract

Rheological Models of Kiwifruit Juice for Processing Applications

Athanasia M. Goula and Konstantinos G. Adamopoulos

Rheological behavior of kiwifruit juice at different solids concentrations (13.5–30 o Brix) and different temperatures (25–65°C) was studied with the objective of defining suitable mathematical models for use in evaporation and other processing procedures. Kiwifruit juice samples exhibited pseudoplastic behavior and were characterized by the power law model. The flow consistency index decreased with an increase in temperature and a decrease in concentration, whereas there was no significant effect of temperature and concentration on flow behavior index. The apparent viscosity at a reference shear rate of 1.0 s -1 ( μ α 1 ) was used instead of the flow consistency index. The temperature and concentration effects on μ α 1 were expressed with a single equation. At low shear rates, kiwifruit juice samples exhibited a thixotropic behavior, which turned to rheopectic at high shear rates. In addition, the Bostwick consistency levels were related to the apparent viscosity measurements and the flow consistency index values.