Equipment freeze-drying

Continuous freeze-drying equipment has been developed(60), and chopped meat and vegetables may be dried in a rotating steam-jacketed tube enclosed in the vacuum chamber. A model of the freeze-drying process has been presented by Dyer and Sunderland191 , and further details are given in Section 15.8 on freeze crystallisation. 

Until atmospheric spray-freeze-drying equipment becomes commercially available, the development of formulation will be mainly based on the Trial and Error approach, and the validation of the classical lyophilization procedure will remain difLcult. 

The freezing process can be performed within the freeze-drying equipment or in separate lines. During freezing outside the freeze-drying line, different methods can be applied ... 

Technical Procedures for Operation of Cleaning-in-Place and Sterilization-in-Place Process for Production Freeze-Drying Equipment... 

Changes and advances in mechanical design of freeze-drying equipment and control systems have had a strong impact. Modem freeze-dryers are easier to use, require less operator intervention and are applicable to a wide variety of products. Current, automated freeze-dryers allow the initial steps of the protocol to be implemented, thereby providing the operator with more data of interest also, they are safer and easier to operate than previous models. 

Freeze-drying equipment is available from several sources on several scales of operation. Manufacturers of laboratory-scale (e.g., bench, scale) lyophilizers include Labconco (Kansas City, MO), VirTis (Gardiner, NY), FTS Systems (New York), and... 

If the product is directly charged on the trays (bulk production) of the freeze drying equipment, it is found to be convenient to have an additional small ice condenser or so-called auxiliary ice condenser that is also connected with the drying chamber, together with the principal ice condenser. A typical sketch of this device (Criofarma model C1200-20) in a plant of 60 m of loading surface is shown in Figure 12.5. 

Criofarma-Freeze Drying Equipment Turin, Italy... 

Table 10.1 Potential non-biological hazards associated with freeze-drying equipment...

Finally, although the equipment should only provide a safe environment for the product and the necessary operating parameters for the lyophilization process, differences in freeze-drying equipment can affect the process. One should be aware of such differences, especially when transferring a process from one dryer to another. So in any discussion of the lyophilization process, the freeze-drying equipment should not be overlooked. 

Fig. 9.9 Laboratory-scale microwave-assisted freeze-drying equipment. 1, MWFD chamber 2, Fiber-optical temperature sensor 3, Vacuum breakage valve, for MWFD 4, Sample supporting plate ...

A typical schematic diagram of microwave-assisted freeze-drying equipment is shown in Fig. 9.9. During drying, the pressure was maintained at 100 Pa by a vacuum pump, and the temperature of the cold trap (—40 to —45 °C) was sufficiently low to condense the vapor. The microwave frequency was 2450 MHz and the power could be regulated continually from 0 to 2000 W. 

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