Transitions and phenomenology of alpha,alpha-trehalose polymorphs inter-conversion

The thermal transitions of alpha,alpha -trehalose polymorphs have been care fully studied by differential scanning calorimetry (DSC) at different scan rates. Attention has been paid to the correlation of the thermal data with the proper crystalline forms (when present), in order to attribute the obse rved transitions correctly. In particular, the subtle dehydration process o f dihydrate trehalose has been already shown to produce several species, de pending on the experimental conditions. Thermodynamic data (i.e., temperatures and enthalpies) for all the known tr ansitions are reported and the results are critically discussed.