ABSTRACT
The freeze-drying process is, at a minimum, two processes — freezing and sublimation drying. On the basis of the foregoing tables, it can be said that freeze-drying of foods can give dehydrated products with little loss of nutritional value beyond that occurring in the predrying steps. The storage stability of freeze-dried products has been a subject of much study. Information regarding the retention of nutrients during freeze-drying can sometimes be obtained from these studies if and when the authors have thought to report the nutrient content of their original raw material. When describing the freeze-drying process itself, the steps include freezing of the product water to ice, sublimation of the ice crystals so produced, and desorption of the unfrozen water. Storage stability studies are generally conducted at conditions of temperature, moisture, and time that are quite different from freeze-drying conditions.
