Flow Properties of Low-Pulp Concentrated Orange Juice: Effect of Temperature and Concentration |
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| Authors: | A A VITALI M A RAO |
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| Affiliation: | Author Rao is affiliated with the Dept. of Food Science &Technology, New York State Agricultural Experiment Station, Cornell Univ., Geneva, NY 14456.;Author Vitali, formerly with Cornell Univ., is now with the Instituto de Tecnologia de Alimentos, Caixa Postal 139, 13.100 Campinas, Brazil. |
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| Abstract: | Three 65° Brix low-pulp concentrated orange juice (COJ) samples, between ?19 and 30°C were shear-thinning (pseudoplastic) fluids with negligible magnitudes of yield stress. The simple power law model fit welt the shear rate-shear stress data. For one sample, the Powell-Eyring model also described the data well. The Arrhenius model described the effect of temperature on the apparent viscosity and the consistency index of the power law model. The activation energy of flow (Ea) was 10.7 ± 0.2 kcal/g mole. The models of Harper and El Sahrigi and Christiansen and Craig were suitable for describing the combined effect of temperature and shear rate. The magnitude of Ea decreased with decrease in concentration. Apparent viscosity and K increased exponeitially with concentration. |
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