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A new method for measuring the glass transition temperature of aqueous solution and food by DSC.

Author(s) : ZHOU G. Y., YE X. D., HUA T. C.

Summary

Glass transition temperature is a very important parameter in freeze-drying and cryopreservation. The glass-transition temperature of the maximally freeze-concentrated solution (Tg') can not be obtained directly, although there are many methods to measure it. Otherwise the glass-transition temperature of the partially freeze-concentrated solution (Tgf) can always be obtained directly. In this paper, the new concept of Tgf is brought forward and a new method is gave for measuring Tgf of aqueous solution and food 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. 20 and 45% glucose, 10 and 25% PVP and concentrated strawberry juice solution are chosen as samples. For glucose, it is found that the Tgf increases initially with annealing temperature up to -50°C, and decrease as the temperature continues to increase and exhibition linear relation obviously. It takes on the same disciplinarian for glucose of different concentrations. It is concluded that the Tg' can be determined by intersection of the two curves reflecting the Tgf change with annealing temperature. The optimal annealing temperature (-50°C) and accurate glass transition temperature (Tg', -55.3°C, onset) of glucose are obtained. It takes on the same disciplinarian for PVP and strawberry juice solutions (linear relation). The optimal annealing temperature (-14, -49.5°C) and accurate glass transition temperature (Tg', -18.1, -52.8°C, onset) of PVP and strawberry juice solutions are respectively obtained.

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Pages: ICR07-C1-1331

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Details

  • Original title: A new method for measuring the glass transition temperature of aqueous solution and food by DSC.
  • Record ID : 2007-2828
  • Languages: English
  • Source: ICR 2007. Refrigeration Creates the Future. Proceedings of the 22nd IIR International Congress of Refrigeration.
  • Publication date: 2007/08/21

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