Intermittent Microwave Drying of Apple Slices: Drying Kinetics, Modeling, Rehydration Ratio and Effective Moisture Diffusivity

Abstract

In this research, thin layer drying characteristics, rehydrationratio and effective moisture diffusivity of apple wereinvestigated using microwave dryer which has intermittentand continuous modes. Drying time varied between 25 and215 minutes and they declined with the rise in microwavepower and reduction in pulsing ratio. In an attempt to pickthe optimum thin layer models for the drying applications, 8mathematical models suited to the experimental results. Onthe grounds of the statistical tests evaluation, Midilli et almodel which represent drying characteristics are optimallysuited than other models. The highest rehydration ratio wasrecorded for the samples dried at 100W continuous mode andthe lowest ratio at 300W continuous application. Effectivemoisture diffusivity values were computed by the 2nd law ofFick and changing between 3.04x10-9 and 2.53x10-8 m2 s-1.Consequently, the intermittent microwave method could beused as a favorable drying method for obtaining high-qualityfruit slices or processing valuable material and continuousmicrowave drying can be taken as another drying approachfor apple samples.