The influence of pressure and temperature on freeze-drying in an adsorbent medium and establishment of drying strategies

A study of freeze-drying (lyophilization), by immersion in an adsorbent medium (LIAM), was carried out, both at atmospheric pressure and under vacuum. The pressure and temperature effect on the drying kinetics and on the final dehydrated quality were evaluated. The kinetic analysis of both techniques has been carried out through one model that considers a uniformly retreating ice front in spherical geometry. This model calculates the pressure and temperature in the sublimation front in terms of the product moisture. Some operational strategies have been proposed which reduce the process duration without serious damage to the product. In these strategies the temperature and pressure in the fluid bed are modified. (C) 1997 Canadian Institute of Food Science and Technology. Published by Elsevier Science Ltd.