3.3 Steps of a
Freeze-Drying Protocol
The general steps for freeze-drying proteins are:
1. Switch on freeze dryer and vacuum pump.
2. Make formulation mixtures by adding additives to the protein
solution.
3. Dispense mixtures into glassware.
4. Freeze containers with the sample mixtures.
5. Primary drying.
6. Secondary drying.
7. Conditioning-packing and storage.
3.4 Freeze-Drying
Cycle Design
Generally, a freeze-drying cycle includes freezing (solidification),
primary drying (sublimation), and secondary drying (desorption)
as shown in Fig. 1. This figure also indicates the variations of the
material temperature and the moisture during freeze-drying
processes [8].
3.5 Freezing
Samples should be properly frozen during the freezing step (see
Note 7).
1. Freezing can be done in one of the three ways as (a) by dipping
or immersing into liquid nitrogen, (b) in a specified freezer or
(c) inside the freeze dryer. The freezing rate is important (see
Note 8).
Fig. 1 Variations in sample temperature and moisture content during freezedrying processes
Freeze-Drying of Proteins
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