Mathematical Modeling of Goat Meat Drying Kinetics with Thermal Oscillations

Goat meat has a high nutritional value, since it contains up to 29% protein, as well as iron, potassium and vitamin B12. To prolong the shelf life of this food, a drying process can be applied; however, there is scarce information on the kinetics and drying parameters for this food material. The objective of this work was to characterize the thermal drying process of goat meat, through the mathematical modeling of convective drying kinetics, and its validation with experimental data obtained in a drying tunnel. The experiments were carried out with samples of loin (Longissumus dorsi) of Boer goat meat from the Mixteca region of Oaxaca (Mexico). Meat samples were subjected to air convection drying at 40, 50, 60 and 70 °C (with temperature oscillation), with air velocities of 1 and 2 m/s. Drying kinetics, air and meat temperature profiles, relative humidity and air flow velocity were recorded. Four models were analyzed: two-term, Midilli's model, Wang and Singh's model and a heuristic model with temperature dependence. The proposed mathematical models represented drying kinetics with an accurate fitting of experimental data, with standard errors (RMSE) in the range of 0.004-0.029. The estimated diffusion coefficients are consistent with the transport properties in biomaterials. The heuristic model was based on the solution of the effective diffusion equation considering the linearization of the temperature-dependent diffusion coefficient, showing a standard error in the range of 0.007-0.028, satisfactorily representing the temperature oscillations that allows a moisture diffusion reorganization, mainly when drastic temperature changes occur.