This research aims to study the effects of temperature and concentration on the density and viscosity of pineapple juice and passion fruit juice. Pineapple juice and passion fruit juice were experimentally evaluated for viscosity (using Brookfield Rotating Spindle) and density (using Pycnometer). The viscosities and densities of pineapple juice were determined at concentrations of between 10 – 60.8 0Brix and temperature of between 5 and 72 0C. The viscosities and densities of passion fruit juice were determined at concentrations of between 7 – 13.8 0Brix and same range of temperature. Pineapple juice behave as Newtonian liquids. But passion fruit juice behave as Non-Newtonian liquids. In addition , the results were analyzed to obtain this property as functions of temperature and concentrate in mathematics models.Viscosity’s equation of pineapple juice was refer from Arrhenius relationship. Viscosity’s equation of passion fruit juice was refer from Power Law Model And Densities, equation was refer from least-squares method.The density of pine apple juice’s equation was = 1030.7912-0.4643T+2.8199C+0.0284C2,R2 = 0.9971.The density of passion fruit juice’s equation was = 1040.2378-0.4606T-2.1939C+0.2962C2,R2 = 0.9855.The viscosity of pineapple juice’s equation was = 0.7981exp(6.8942T-0.0293C +0.00187C2),R2 = 0.9396. The Power law index of passion fruit’s equation was n = -0.1352+0.0473C+0.0083T-0.00002T2,R2 = 0.9363.The consistency index of passion fruit’s equation was k = 2.5437+ 0.0019T-0.6870C+0.0485C2, R2 = 0.9669.
By
Natthakool Tachawitayawatana
Peerada Thunwarachara
Hngungruthai Supruegtaveechai
