ABSTRACT
Amorphous and crystalline powder products possess different properties. R. Price and P. M. Young stated that the propensity of crystallization from amorphous products to crystallize limits the ability of amorphous products to provide high bioavailability for drugs. H. M. Lai and S. J. Schmidt found that the crystallization process could be followed by nuclear magnetic resonance measurements, but it was necessary to enrich the skim milk powder with heavy water and deuterium salts, suggesting that this method has only limited practical value. G. Chen and G. Z. Xie create a drying “fingerprint” for each material, which is a unique function that expresses the relationship between the activation energy for drying and the moisture content, for any given material. Powders produced by very small-scale spray dryers can be kept free flowing for a long time by freezing them, because the freezing reduces the particle temperature, reducing the rate of transformation from amorphous to crystalline product.
