Abstract
Complex impedance was measured to analyze ice crystal morphology for frozen gelatin solutions from 5Hz to 100kHz at -20℃. Samples with different freezing rate were prepared by program freezer over a temperature range of -120 to -20℃. The maximum vales of dielectric loss (ε") were different from freezing rate at 1250Hz. A Micro-Slicer Image Processing System (MSIPS) has been applied to observe the ice crystal structure formed in frozen gelatin solutions. The equivalent diameters of ice crystals were measured quantitatively, based on images obtained by multi-slicing of a frozen sample with the thickness of 5 μm. The equivalent diameter of ice crystals was in the range of 31.7 μm up to 54.3 μm, and then at the freezing rate of 37.0 to 219.5℃ h^<-1>. The electric conductivity of whole sample was in the range of 1.24×10^<-6> up to 3.63×10^<-6>. The study therefore suggests that measuring the dielectric properties of frozen liquid food materials may be associated with ice crystal morphology and may be of considerable use of understanding the internal structure of frozen materials.
