Centrifugal Vacuum Freezing: Its Aapplication to the Drying of Biological Materials from the Frozen State

Abstract

MANY biological materials can be most conveniently preserved in one way only, namely, if they are dried from the frozen state. The success of the 'freeze-drying' procedure appears to be chiefly related to the fact that the resulting 'solid state' prevents the concentration and aggregation of the molecules of protein which, when they are dried from the liquid state, leads to their denaturation. The temperature of drying is of little importance provided it is, below the eutectic point of the material and so causes the solid state to be maintained throughout the period of desiccation. Moreover, on slow freezing, concentration of proteins and salts takes place. Therefore, to get the best dried product, particular attention must be paid to the freezing of the solutions.