PROCESS FOR FREEZE DRYING WITH CARBON DIOXIDE

• US 3,673,698 A
• Filed: 11/25/1970
• Issued: 07/04/1972
• Est. Priority Date: 11/25/1970
• Status: Expired due to Term

• Current Assignee: Albert S. Guerard
• Original Assignee: Albert S. Guerard
• Inventors: Guerard, Albert S.
• Primary Examiner(s): Matteson, Frederick L.
• Assistant Examiner(s): Anderson, W. C.
• Application Number:
  US05/092,791
• Time in Patent Office: 587 Days
• Field of Search: 34/5,10,15,92
• US Class Current: 34/284
• CPC Class Codes: A23F 5/32 by lyophilisation
• CPC Class Codes: F26B 5/065 the product to be freeze-dried being sprayed, dispersed or pulverised

Abstract

A continuous process is provided for the improved freeze drying of an aqueous solution to remove the water by sublimation from ice crystals to produce a dry product which can be reconstituted with water more readily than like products heretofore. Such aqueous solutions comprise coffee or tea syrups, fruit juices, milk, eggs, broths and the like.

Claims

2. A process as in claim 1, wherein the crystals in the second zone form a bed in such second zone and dry carbon dioxide gas is passed upwardly through the bed of crystals to maintain the bed in a fluidized condition, the temperature and vapor pressure of the injected carbon dioxide being effective to cause sublimation of ice and solid carbon dioxide in the crystals, said temperature of injected carbon dioxide gas being insufficient to thaw the frozen solid residue of the infusion, and recovering the frozen solid residue free of water and carbon dioxide.

3. A process as in claim 1, wherein the carbon dioxide vapor in the first zone is removed, dried and then returned to the second zone wherein the dry carbon dioxide gas is passed upwardly through the bed of crystals to maintain the bed in a fluidized condition, the temperature and vapor pressure of the injected carbon dioxide being effective to cause sublimation of ice and solid carbon dioxide in the crystals, the temperature being insufficient to thaw the frozen solid residue of the infusion, and recovering the frozen solid residue free of water and carbon dioxide.

4. The process of freeze drying material comprising:

a. mixing an aqueous liquid infusion of the material to be freeze dried with an inert, nonreactive, nontoxic, normally gaseous material at a temperature and a first pressure whereat the mixture of the liquid infusion and the normally gaseous material is a liquid;

b. discharging the liquid mixture of normally gaseous material and liquid infusion into a first zone and freezing the liquid mixture in said first zone to produce solid crystals of said normally gaseous material and the liquid infusion;

c. and transferring the solid crystals of normally gaseous material and liquid infusion to a second zone maintained at a pressure and temperature whereat the normally gaseous material and the water in the solid crystals sublime to leave a solid residue of the infusion free of water and said normally gaseous material to thus freeze dry said material.