Potato slices immersed in 0.5% CaCl2 solution for 10 min were examined using light microscopy for their
microstructure in frozen state before drying, during the sublimation drying stage, in the desorption drying
stage and in the final dried form. Additionally, the final dried product was also tested for vitamin C
content, color, starch content, texture and sugar content. Experiments were carried out using conventional
vacuum freeze dryer as well as a microwave freeze dryer. Results for both unblanched and
blanched potato tissues, crystal growth during sublimation drying stage was observed to cause structural
damage to the cell walls. Blanched tissue suffered more damage during the freezing process. Interestingly,
microwave freeze drying yielded product similar in quality to that obtained in vacuum freeze drying
with conductive heating.