Anhydrous α-lactose A study with DSC and TXRD

The dehydrated lactose forms α_H and α_S were investigated by time- and temperature-resolved X-ray powder diffractometry and differential scanning calorimetry. We found different X-ray structures for these two forms, which is probably related to the different dehydration processes. The rapidly dehydrated form α_H obviously has the same X-ray structure as the starting material α-lactose monohydrate, although the crystallinity is reduced. A thermally induced transition of the α_H-form into the α_S-form was observed. This transition should allow one to “switch” between the physicochemical properties of the excipient, which may be important for applications in pharmaceutical and food industries.