Some remarks on evaluation of drying models of red beet particles

Drying behaviour of red beet particles was investigated in a laboratory type dryer, at constant air velocity 1 m/s and at constant temperature 60 °C. The effect of initial material load, particle shape and size on the dehydration characteristics of red beet was investigated. The drying experiments were conducted at three levels of initial material load of 5.33, 10.67 and 16 kg/m2. The following particle shapes were investigated: slices, cubes, and prisms. Red beet roots were cut into 3, 6 and 9 mm slice thickness, 6, 9 and 12 mm cube thickness, and 3, 6 and 9 mm prisms thickness. Length of square based prisms equalled 50 mm. The results have shown that, the initial material load, particle shape and size influence on the drying behaviour of red beet particles. The experimental dehydration data of red beet particles obtained were fitted to the semi-theoretical, empirical and theoretical models. The accuracies of the models were measured using the correlation coefficient (R), mean bias error (MBE), root mean square error (RMSE), reduced chi-square (χ2), and t-statistic method. All models except that used by Wang and Singh described the drying characteristics of red beet particles satisfactorily. The effect of the characteristic dimension of the particle and initial material load on the drying models parameters were also determined.