Relationship between ice recrystallisation rates and the glass transition in frozen sugar solutions

The increase in ice crystal size that occurs through recrystallisation when many frozen products such as ice cream and frozen desserts are stored is one of the major factors contributing to the perceived deterioration of the product by the consumer. In order to reduce the rate of deterioration, a detailed understanding of the fundamental mechanism is needed. This study demonstrates that ice recrystallisation rates in a series of frozen sugar solutions are strongly correlated with the molecular mobilities of the water and solute molecules as measured by time domain nuclear magnetic resonance. The study also demonstrates that the proximity to the glass transition temperature as described by state diagrams correlates well with the measured ice recrystallisation rates. The temperature dependence in these systems is described by Williams, Landel and Ferry theory. (C) 2002 Society of Chemical Industry.