Crystallization characteristics of amorphous trehalose dried from alcohol

Trehalose forms a glass that can be used to preserve labile substances under desiccation. The crystallization characteristics, namely crystallization temperature (Tcry) and isothermal crystallization behavior of amorphous trehalose, dried from alcohol (methanol, ethanol), was analyzed and the results were compared with those for the amorphous trehalose freeze-dried from water. The use of alcohol as a solvent lowered the Tcry from 184 ± 6 °C for the case of an aqueous solvent to 103 ± 5 °C/methanol and 120 ± 8 °C/ethanol. The formation of multiple forms of crystals and partial melting were suggested by the thermal analysis. Isothermal crystallization experiments showed that the alcohol-originated amorphous trehalose was eventually exclusively converted into β-form crystals. The induction period (tind) before the start of isothermal crystallization was markedly shortened when alcohol was used as the solvent compared to water. The tind values for various amorphous sugar samples including the alcohol-originated ones could be correlated with difference between Tcry and the sample temperature.