How to Adapt a Lab-Scale Freeze Dryer for Assessing Dehydrating Curves at Different Heating Conditions

A laboratory-scale freeze dryer was adapted to allow control of the heat supply and on-line monitoring of sample weight during drying under vacuum condition. Several tests were carried out to verify the reliability of the developed system. The system was also tested with 10-mm-thick banana slices, obtaining the fruit drying rate, at different sample holder plate temperatures including 20 and 30 degrees C as well as an unheated plate. The system presented in this work represents a low-cost, flexible, and easy-to-assemble piece of equipment that allows the study and optimization of the freeze drying of foods.