Edited by Daud et al. MODELING ON RHEOLOGICAL PROPERTIES OF TROPICAL FRUIT JUICES

Fruit juice industry is one of the world’s biggest agribusinesses. During processing, it deals with juice in a variety of concentrations and temperatures. In order to have a suitable process design, operation and control, knowledge of rheological behaviour of the fruit juice is of fundamental importance. The aim of this work was to measure the viscosity and density of fruit juice as a function of temperature and juice concentration and to obtain simple equations to correlate experimental data. The flow properties of water extract of Noni fruit were determined using a concentric cylinders rotational viscometer for extract concentration of 35 and 65 % TS, temperature range of 30-60°C and shear rate range of 2.5-950 s-1. The measured shear stress was within 0.5 to 50 Pa, corresponding to viscosity range of 0.0015-1.6 Pa.s. Within the tested conditions, the extract exhibited a pseudo plastic behaviour. The experimental results were well fitted by power law models