Abstract
This work deals with the study of drying kinetics of high water content materials such as agro-food particles. These materials exhibit significant structural and geometry changes during drying showing complex non-Fickian drying kinetics. Indeed, drying rate curves in these cases show multiple stages differing significantly from typical constant and falling rates periods. These observations justify the need to characterize the drying curves differently to account for this behavior. For instance, following experimental measurements, it has been found that Fickian type kinetics (Ae(-kt)) do not hold for characterizing the drying curves; instead, the suitability of a modified Page's type model (1-term : Ae(-alpha t2 center dot(kt)n)) has been justified where the parameter (k) is the rate constant and (n) characterizes the tissue. For the purpose of analyzing the drying kinetics more suitably, multiple drying stages have been detected by the simultaneous use of the three typical curves : (i) MR.vs. t, (ii) -dMR/dt .vs. MR, and (iii) F-o* .vs. t, where F-o* = (kt)(n), where F-o* is a modified mass transfer Fourier number. By plotting all three curves on the same graph one can trace all the drying stages corresponding to different water diffusion rates thus reflecting the structural changes due to thermal effects.