Recrystallization of Ice Crystals in Sucrose Solution Containing Sodium Alginate and Its Relationship to Dynamic State of Freeze-concentrated Matrix Evaluated by Dielectric Relaxation Measurement.

The effect of sodium alginate addition on the recrystallization of ice crystals in 40% sucrose solution at -10 oC was experimentally determined. The dynamic state of the freeze-concentrated matrix was investigated by the dielectric relaxation measurements to discuss the mechanism of sodium alginate addition effect on the ice recrystallization. The recrystallization of ice crystals was significantly inhibited by the addition of 3%, 5%, and 10% alginate. And the recrystallization rate constant tended to decrease with increasing alginate concentration. The dielectric relaxation behavior of all samples was well fitted by the combined equation of the two Cole-Cole relaxations indicating the existence of two relaxation process with different relaxation time: fast and slow processes. Based on the preceding research, the fast one and slow one was interpreted as relaxation of free water and that of solute-coupled water, respectively. Increasing sodium alginate concentration, both the fast and slow relaxation time tended to become larger, indicating that slower water mobility in freeze-concentrated phase. This result suggested that the slower water mobility by addition of sodium alginate contributed to the ice recrystallization suppression. [ABSTRACT FROM AUTHOR]