Freeze-drying history

The study of the irradiation of ice has a long history due, in part, to the considerable interest in radiation biology in the 1950 s and 1960 s. Freeze-dried samples of biomolecules were often irradiated and compared, spectrally... 

Many authors, in different comprehensive books dedicated to freeze-drying, have already described in full detail the scientific history of this method [3], and we will not attempt to do it again. Moreover, in the last 60 years, much research and substantial development have been devoted to freeze-drying, and it would be of little use to list papers that are well known and available to all of the specialists concerned. 

Successful freeze-drying, on a commercial scale, of essentially labile materials depends on a detailed understanding of the complex interplay between several disciplines ice physics, chemistry of supersaturated solutions, pharmacology, materials science of water sensitive materials, engineering of coupled heat and mass transfer, production economics and IP law. The case histories discussed in this chapter originate mainly from projects undertaken by the author and his colleagues at Pafra Biopreservation during the period 1985-1999 and from various consultancy projects undertaken by the author since that time. ... 

Figure 20.4 History of the surface temperature for slush drying and freeze-drying...

A fundamental paradigm of freeze-drying is to understand that, in almost every case, there is no direct correlation between the structure of a frozen product and its temperature since all structural features depend essentially on the thermal history of the material. In other words, the knowledge of the temperature of a frozen solution is not enough to allow the operator to know its structure since this latter depends, essentially, upon the way this temperature has been reached, i.e., upon the freezing cycle. 

III. FREEZE-DRYING MECHANICAL HISTORY A. Shelf Freezing and Heating... 

Figure 22 shows the pho hate profiles of freeze-dried saliva resuspended in a buffer solution. The top spectrum was obtained from a patient with a history of dental caries and relatively good oral hygenic habits. The principal signal arises from salivary inorganic orthophosphate. The other resonances arise from various phosphomono- and diesters. The monoester resonance band appears at 3.95 ppm and corresponds to approximately 43% of the... 

Desorption rates not only document the progress of SD and permit the calculation of dW, they also reflect the history of the product during freezing and main drying. For technical details see Section 1.2.3. 

The ensuing suite of minerals that theoretically precipitate are, however, different for these two scenarios. For example, drying by evaporation leads to precipitation of predominantly halite (NaCl), while freezing leads to predominantly hydrohalite (NaCl-2H20) (Fig. 5.14a-b). If states of mineral hydration are preserved in ocean or lacustrine deposits on Mars, then these records could provide valuable clues to the environmental history of Mars during the drying process. 

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