Recent Advances in the Freeze-Drying of Food Products

Abstract

This chapter presents a critical survey of present-day thought on the freeze-drying of foods. The chief purpose is to present a critical survey of the literature. A wide coverage of investigations on freezing has been included; it is becoming increasingly apparent that the freezing step is a particularly important phase of freeze-drying, and may well be the most significant. It discusses freeze-drying equipment in rather elaborate detail, because at present, there is no published comprehensive survey of freeze-drying equipment. All freeze-drying systems arc composed of: (1) a drying chamber and (2) some system to evacuate vapors and maintain low pressure conditions. Most recent equipment developed on the drying chamber has been discussed briefly. The chapter not only discusses the really new developments but also detailed descriptions of all major components of modern freeze-drying equipment are included. This is done both to present a complete description of modern practice in a single reference and to keep discussions of specific innovations from appearing fragmentary. The chapter concludes with a discussion on the applications of freeze-drying to foods.