30F-6 |
A simplified equation to calculate the drying kinetics of carrot and cassava |
E. HERMAN-LARA, Dept. Biochemical Engineering, Instituto Tecnologico de Tuxtepec, Calz. Dr Victor Bravo Ahuja s/n, Col. 5 de Mayo, Villahermosa, 68360, Mexico and M. A. García-Alvarado, Dept. Biochemical Engineering, Instituto Tecnologico de Veracruz, Miguel A. de Quevedo No.2779, Col. Formando Hogar, Veracruz, Ver., 91860, Mexico. Solid-water equilibrium relationship plays an important role during the drying process of the food. The most mathematical simulations of food drying have employed sorption isotherms obtained from water activity experimental and calculated data. Time and complexity employed for calculating the mathematical simulations of the drying processes is huge in many cases. The objective was to obtain a mathematical expression to compute the drying kinetics of cassava and carrot at different thickness of slab. The mathematical simulations were obtained by a rigorous modeling. The mathematical model employed was a system of four coupled non-lineal partial differential equations that represented the heat and mass balances of solid and air in conjunction with three non-lineal algebraic equations that represented the heat and mass balance and equilibrium relationship in gas-solid interface. This system was solved numerically using the finite difference and Runge-Kutta methods. All the drying simulations of carrot and cassava employed sorption parameters from water activity calculated and experimental data at temperatures between 65-50 degree Celsius. Thickness food slabs employed were 0.1 and 1.0 cm. Results showed that interfacial moisture content was negligible through the time and space in relation to initial moisture content of the food at thickness of 1.0 cm at different temperatures. Therefore, a simplified equation was obtained to calculate the moisture evolution of carrot and cassava. Nevertheless, at thickness of 0.1 cm, results showed that the interfacial moisture content was changing through the time and space, and not was negligible in relation to solid moisture content. It was not possible in this case to obtain an analytical equation. Therefore, it is possible to obtain simplified equation for reducing the solution time of the simulation of food drying at thick slabs without the necessity of having complex equation systems.
Session 30F, Food Engineering: Transport processes and kinetics
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