Measurement and Correlation of the Solubility of Carbohydrates in Subcritical Water

The measurement and correlation of the high-temperature aqueous solubilities of three different carbohydrates (glucose, maltose, xylose, etc.) between 293 and 453 K are reported in this study. Sugar solubilities were measured by a continuous-flow technique in which the sugar is saturated at various temperatures in a stream of flowing hot water. Sugar solubilities were measured on the diluted samples taken in the "saturation plateau" region of the solubility measurement technique. Because of a large increase in the sugar solubility with temperature, particularly above the boiling point of water, adjustments in the size and amount of solute in the saturation cell as well as an adjustment of the dilution water rate were necessary. The determined sugar solubility values compare favorably with existing data below the boiling point of water and provide nonexisting data over the above temperature range above the boiling point of water. The resultant sugar solubility trends were modeled empirically or by use of a modified Apelblat equation or the A-UNIFAC model.