The method of preparation strongly influenced the pharmaceutically relevant properties of amorphous trehalose. The resistance to crystallization can be rank ordered as trehalose prepared by dehydration < freeze-dried approximately spray-dried < melt-quenched. The rate of water sorption can be rank ordered as trehalose prepared by dehydration < freeze-dried < spray-dried.

Thermal history of amorphous materials is a crucial determinant of their physical properties. Aging of amorphous trehalose led to nucleation below the Tg, and decrease in rate and extent of water sorption. Sorption of water resulted in irreversible changes in the relaxation state of the aged material.

The extent of lattice order in anhydrous trehalose T(alpha) was dictated by the kinetics of water removal from trehalose dihydrate. The partially crystalline nature of anhydrous trehalose produced by dehydration could be described on a continuous scale of lattice order based on the one-state model of crystallinity.

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