Freeze-drying books

Industrial freeze-drying began with the production of preserved blood plasma and penicillin, as shown by E. W. Flosdorf in his book Freeze-drying in 1949. 

The book describes the up-to-date fundamentals of freezedrying, not just presenting the process in all its seven steps theoretically, but explaining it with many practical examples. Many years of experience in freeze-drying allow the authors to supply valuable criteria for the selection of laboratory, pilot and production plants, discussing the advantages, drawbacks and limitations of different plant designs. 

Subsequent to freeze stabilization, wet books can be thawed and air dried with or without interleaving or they can be vacuum dried in heated chambers (5). The moisture in frozen books can be sublimed by freeze drying (10) or removed by a vacuum/thaw/outgassing process (8), with microwave energy (6, 14), with dielectric energy (6), or by solvent extraction with or without vacuum assistance (5). 

Freeze-thaw vacuum, inter leave-air, and solvent extraction processes offer the greatest potential in drying these types of coated- and uncoated-paper books after they have been wetted and frozen. The drained-air, vacuum-air cycle, vacuum, microwave, and dielectric drying processes work well on uncoated paper, but they fail to dry books containing this type of coated paper. Small and large units for freeze-thaw, vacuum drying have been used successfully to remove water from these frozen coated and uncoated books. 

When the extent of damage was determined for the thawed book, a decision was then made on whether to go ahead immediately with the restoration process, including the best drying approach, or to again freeze the book. The latter approach was taken in the majority of the cases since the special restoration techniques that were required could only be supplied when the appropriate talent became available. 

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. 

Today, 40 years later, we are pleased to see that freeze-drying still holds a remarkable place in our multiple panel of advanced technologies and more particularly in the pharmaceutical field. It was thus a wise and sound decision of our publisher to propose that a collective book be devoted to that topic. 

The primary structure of the fluids that are bound to undergo freeze-drying is, of course, of great interest. In that wake, the structure of water itself is a determinant item. This is why two chapters in this book relate directly to that topic (Watts and Bellissent-Funel/Teixeira). Accordingly, we will not deal with it. However, we would like to share with our readers and colleagues some ideas that evolved from recent experiments that we have carried out on the low-temperature thermoluminescence of different systems and, in particular, on water itself. 

Industrial freeze-drying has been in use for more than 60 years in the pharmaceutical field, but it is still a challenging process and we are certain that it will keep a leading role in the preservation of refined biochemicals and drugs in the coming years. It is our hope that this book constitutes a valid contribution to this development. 

The purpose of Freeze-Drying/Lyophilization of Pharmaceutical and Biological Products is not to present an exhaustive view of the process, but essentially to shed light on some focal areas of the field in which pioneering research has been achieved and assess its impact on current manufacturing practices. This book also provides a critical review of such wide issues as the design and construction of equipment to identify the main trends and sometimes locate the specific sectors where our technological know-how is still incomplete. 

There are, however, many other possible uses for freeze-drying that include the preservation of microbial cultures, the restoration of books and other objects damaged by water, the concentration and recovery of reaction products, and the preservation of whole animal specimens as a form of taxidermy. 

The book is thus a distillate of our acquired knowledge and experience. Of necessity, this experience is limited to what my colleague Tony Auffret came to call the hospital cases of freeze-drying. Those without problems do not require the services of consultants. Our approach to the subject rests on two fundamental principles (1) everything that a skilled engineer might contribute to the development of an efficient and economical process depends on the formulation details of the solution to be dried in other words, every formulation is accompanied by an optimum... 

The choice of a particular drying method is also partly dictated by the scale of the operation. Where it is necessary to remove vast quantities of water from a very dilute solution, e.g. for purposes of waste water purification, freeze-drying is completely unrealistic. On the other hand, the method has been successfully used to dry valuable books and documents in libraries that have suffered flood damage. 

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