Differential scanning calorimetric study of frozen sucrose and glycerol solutions

Differential scanning calorimetry (DSC) thermograms have been recorded for sucrose and glycerol solutions as a function of moisture content. Simple second-order transitions were observed at the glass transition for the higher concentration samples which did not form ice. More complicated thermograms were observed from the lower solution concentrations which formed ice. The origin of these transitions in the DSC thermograms from frozen solutions is discussed, together with the methods used to calculate the amount of ice in the freeze-concentrated solutions. The glass-transition temperatures (Tg) and the ice-melting temperatures (Tm) were used to construct the supplemented phase diagrams for both of these solutes. The maximum freeze concentration (C′g) for sucrose is determined to be 81.2% sucrose, and is shown by a novel experimental approach to occur at a temperature (T′g) of –40 °C.