Quantitative evaluation of time-dependent changes of ice crystals in frozen food by using fractal analysis.

The shape of ice crystals in frozen food materials are very important because they affect not only quality of frozen foods but also the viability of industrial processing such as freeze-drying or freeze concentration. However, the method to evaluate complicated shape of ice crystals in food has not been yet established in a scientific manner. In this study, the shape of the ice crystals was quantitatively evaluated by introducing the fractal analysis to examine how they are influenced by various storage temperatures. Fractal dimension was obtained from the relationship between the area and the peripheral length of the ice crystals. Thus, the changing rate of fractal dimension could be determined. Furthermore, the temperature dependence of the changing rate was analysed by Arrhenius plot, resultantly the activation energy was obtained.