CHAPTER VII 



QUICK-FREEZING AND THE 

 FREEZING-DRYING PROCESS 



Earl W. FlOSDORF, F. J. Stokes Machine Co. 



A. Principle of Quick-Freezing 211 



B. Principle of Dehydrating Frozen Materials 212 



C. Potential Applications 214 



1 . Quick-Freezing Materials for Storage 214 



2 . Low Temperature Chemical Manipulations 215 



3 . Preservation of Laboratory Cultures 215 



4. Preservation of Body Fluids and Miscellaneous Products. . 216 



5. Histological and Cytological Preparations 218 



6. Commercial Processing of Heat-Sensitive Materials 218 



D. Equipment for Freezing and Dehydrating 219 



1 . Sources of Low Temperature 219 



2. Apparatus for Dehydrating Frozen Material 221 



E. Technical Operations and Limitations 221 



1 . Criteria for Quality of Preservation 221 



2 . Optimum Dehydrating Conditions 222 



3 . Production Scale Processing 224 



4 . Role of Protective Proteins 225 



5 . Oxidation as a Factor in Preservation 225 



6. Storage and Use of Products 226 



F. Some Outstanding Accomplishments 226 



1 . Virus Research and Distribution of Vaccines 226 



2 . Bacterial Preservation 228 



3 . Preservation of Miscellaneous Products 229 



References 231 



A. PRINCIPLE OF QUICK-FREEZING 



By freezing living organisms and tissues quickly, it is often possible 

 to prevent alteration in their chemical and biological characteristics. 

 Eutectic separation with resulting concentration of components is 

 avoided. This is in contrast with slow freezing, in which two or more 

 phases are obtained, the phase to solidify first consisting of solvent 



211 



