Influence of blanching-freezing pre-treatment on moisture removal characteristics of microwave-dried potatoes

The aim of present work was mainly to study the influence of blanching-freezing pre-treatment on moisture removal characteristics of potato during microwave drying process. The influence of microwave power and the samples thickness was also assessed. For this purpose, microwave powers of 100, 350 and 550 W were practiced to dry discoid shape samples of fresh and blanched-frozen potatoes with a constant diameter of 20 mm and different thicknesses of 5, 10 and 15 mm. The obtained results revealed that time required to dehydrate treated potatoes was significantly (P < 0.05) shorter than the fresh ones. The moisture diffusivity of the fresh and blanched-frozen potatoes was determined to be in the range of 9.13 × 10−9‒7.93 × 10−8 and 9.89 × 10−9‒9.36 × 10−8 m2 s−1, respectively where enhanced with the both increasing power level and samples thickness. The average energy required to instigate water diffusion inside the treated samples with 5, 10 and 15 mm thickness was obtained to be 0.463, 0.379 and 0.331 W g−1, respectively while the values for fresh samples were 0.505, 0.466 and 0.413 W g−1, respectively.