Compression of Foods during Freeze-Drying: Water Plasticization at the Ice-Dry Layer Interface

  • C. Emami
  • J. M. Flink
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 302)


The compressive mechanical properties of freeze-dried green beans show a pronounced decrease in rigidity when moisture content and/or temperature are increased. There exist several temperature and moisture combinations which give common values for mechanical properties. These combinations also give a common compressive behavior. Using this information on mechanical properties, it is possible to predict a stress-strain relationship, if given either a temperature, a moisture content, or the value of a pertinent mechanical property.

It is shown that the moisture contents and temperatures that exist in the dry layer during freeze-drying result in mechanical properties that are suitable for compression of the dry layer. From studies on compression behavior during freeze-drying, it is shown that applied compressive pressure is the main determinant of final degree of compression. Increasing the compressive pressure gave a higher compression effect and gave a more rapid drying, presumably due to improved heat transfer in the compressed dry layer.

From the above information, a simple method to predict compression behavior during freeze-drying was developed.


Compressive Pressure Compression Behavior Tangent Modulus Green Bean Instron Test Machine 
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Copyright information

© Springer Science+Business Media New York 1991

Authors and Affiliations

  • C. Emami
    • 1
  • J. M. Flink
    • 2
  1. 1.Dunkin’ DonutBraintreeUSA
  2. 2.Novo Food Diagnostics A/SFrederiksbergDenmark

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