Abstract: The new concept of the glass-transition temperature of the partially freeze-concentrated solution (Tgf) is brought forward and a new method is given for measuring Tgf of 20% and 45% glucose solution using differential scanning calorimetry (DSC), which is based on annealing samples for long periods of time at different temperatures. The influence of annealing temperature on Tgf is studied. It is found that the Tgf increases initially with annealing temperature up to −50 ℃, and decreases as the temperature continues to increase, and exhibiting a good linear relation in both cases. The same phenomenon was observed for glucose solutions of different concentrations. It is concluded that the Tg′ (glass transition temperature of the maximally freeze-concentrated solution) can be determined from the intersection of the two curves reflecting the Tgf change with annealing temperature. The optimal annealing temperature(−50 ℃) and accurate glass transition temperature(Tg′, −55 ℃） of glucose solution are obtained.

Key words: Glass transition temperature of the maximally free-concentrated solution, Glucose, DSC, Annealing, Glass transition temperature of the partially free-concentrated solution