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DEVELOPMENT OF THE ADSORPTION FREEZE-DRYER.

Author(s) : BELL G. A., MELLOR J. D.

Type of article: Article

Summary

THE LIMITATIONS OF CONVENTIONAL FREEZE-DRYING ARE DUE TO THE VAPOUR-PRESSURE DIFFERENTIAL BETWEEN THE ICE SURFACE IN THE MEDIA BEING DRIED AND THE SURFACE ON THE REFRIGERATION COILS. THE LOWEST REALISTIC TEMPERATURE FOR THE LATTER IS 233 K (-40 DEG C). THE NEW PROCESS WAS DEVELOPED FOR FREEZE-DRYING BIOLOGICAL AND BOTANICAL SPECIMENS. THE AUTHORS FOUND THAT IF VERY RAPID FREEZING COULD BE USED, ICE FORMED IN AN AMORPHOUS STATE WITHIN THE SPECIMEN. IF DRYING COULD BE ACHIEVED AT VERY LOW TEMPERATURES, BELOW 203 K (-70 DEG C), THE ICE SUBLIMATION WOULD OCCUR WITHOUT RECRYSTALLIZATION. SMALL MODELS HAVE BEEN PRODUCED WHICH INCLUDE A SINGLE CHAMBER FOR CONNECTION TO A VACUUM PUMP AND IN WHICH HIGH VACUUMS CAN BE FORMED. THESE CAN BE MADE FOR COOLING IN A CONVENTIONAL FREEZER, OR IN A LIQUID NITROGEN FLASK. D.W.H.

Details

  • Original title: DEVELOPMENT OF THE ADSORPTION FREEZE-DRYER.
  • Record ID : 1987-1620
  • Languages: English
  • Source: CSIRO Food Res. Q. - vol. 46 - n. 3
  • Publication date: 1986
  • Document available for consultation in the library of the IIR headquarters only.

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