Differential Thermal Analysis of α-Lactose Hydrate

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Abstract
Differential thermal analysis was the technique in studying thermal characteristics of .alpha.-lactose hydrate. .alpha.-Lactose hydrate exhibited an endotherm corresponding to the elimination of the water of crystallization, followed by a small exotherm and then by a melting endotherm. Dehydration of .alpha.-lactose hydrate by methanol and heating was recorded clearly on the thermograms as the successive changing into the stable and unstable anhydrous form. .alpha.-Unstable anhydride was characterized by endo- and exothermic peaks at 183 and 190.degree. C. These peaks remained after conversion of the anhydrous form to the crystalline .alpha.-hydrate on exposure to moistened air, though no difference in forms was observed on IR spectra and X-ray diffraction patterns. .alpha.-Lactose hydrate in dried skim milk and dried whey was detectable on the thermogram based on development of the water endotherm. Differential thermal analysis is a promising and useful technique for characterization of lactose.