FreezeDrying of Green Vegetables Under Cyclic Pressure

Under the control of organoleptic quality, the freezedrying test of green onion and carrot was conducted at constant pressure and cyclic pressure. By use of fuzzy optimization, the minimum time required to remove unit water of the samples and the temperature profile in the bed of the samples were found for both models of heat conduction and radiation. To freezedrying granular materials, like green onion and carrot, the optimal drying conditions are as follows: heat transfered to the samples is in the radiation model, and the pressure is cyclically changed from 10 to 1000 Pa. 