‘Collapse’, a structural transition in freeze dried carbohydrates

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Abstract
Summary: A number of techniques used to study ‘collapse’ in freeze dried carbohydrates were described. These include heating of samples in sealed ampoules, DTA, TMA, and various methods involving heating under an optical microscope. Accuracy and reproducibility of ‘collapse’ temperature (Tc) measurements were evaluated. It was shown that glass transitions occur near Tc in a number of freeze dried carbohydrates. ‘Collapse’ was found to occur over a range of temperatures up to 40°C. The extent of ‘collapse’ was quantitatively measured and found to be linear with temperature. Tc was found to be independent of heating rate.