Spectral data are presented showing that the β form of glucose can be changed to the α form while in the solid phase, but this is not reversible. The existence of β-D-glucose hydrate is postulated. Anomer transformation occurs only with the hydrated sugar Rigorous drying of infrared-quality KBr was found unnecessary for use with the sugars.
Leon Segal, "Moisture-Induced Transformations of α- and β-D-Glucoses As Revealed by Infrared Spectroscopy," Appl. Spectrosc. 18, 107-110 (1964)