Crystal transformation from anhydrous alpha-maltose to hydrous beta-maltose and from anhydrous trehalose to hydrous trehalose

Anhydrous sugars such as maltose and trehalose are useful for making dry po wder of foods and liquids, The crystal-transformation rate of maltose and t rehalose were investigated under humid conditions and by kneading. The enth alpy for solubilization was 7.0 kJ/mol for the anhydrous maltose. The cryst al-transformation rate of anhydrous at-maltose to hydrous beta-maltose depe nded on the temperature at 75% humidity. However, that of anhydrous trehalo se did not depend on the temperature, and transformation was very rapid, An anomeric change to maltose and no such change to trehalose might have caus ed this. The activation energy of crystal transformation was 79 kJ/mol for maltose and zero for trehalose. The rate of crystal transformation of anhyd rous maltose while kneading depended on the purity of the anhydrous or-malt ose and the amount of water present. This crystal transformation rate fitte d the Avrami equation.