Among various food processing operations, drying is
the most commonly used method to preserve and reduce
the volume of the food materials. The ``collapse'' of the
dehydrating food during freeze drying, stickiness of the
product during spray drying, caking and agglomeration
of powders during processing and storage are some of
the properties which are related to the glass transition
temperature. This section illustrates the signi®cance of
Tg in various types of drying situations.