Water activity and solubility of trehalose

The water activity, moisture sorption isotherm, and solubility of trehalose were determined. The water activity of a saturated solution of trehalose, as measured by an electric hygrometer, was 0.98 and 0.97 at 20 and 25°C, respectively. The water activity was also measured by a Decagon water activity instrument and found to be 0.96 and 0.95 at 20 and 25°C, respectively. The moisture sorption isotherm of trehalose at 20°C was found to be a Type III isotherm. Trehalose solubility from 10–40°C was determined using a two step method. The solubility of trehalose in water at 10, 20, 30, and 40°C was found to be 42.3, 46.6, 52.3 and 59.7% (g trehalose 100 g−1 solution), respectively.