Prediction and Control of Ice Crystal Growth in Frozen Foods

Several research aiming at systematic understanding, prediction and control of ice recr ystallization in frozen foods were reviewed. The change of ice cr ystal shape under recrystallization was numerically estimated by using the concept of fractal. The recrystallization rate constants of various sugar solutions showed good correlation to the properties of water in freeze-concentrated matrix; diffusion coefficient, spin - spin relaxation time T 2 , and dielectric relaxation time. This suggested that these are useful for predicting recrystallization of ice crystals in frozen foods. The recrystallization of ice crystals in sucrose solution were greatly suppressed if its freeze-concentrated matrixes were in glassy state. The ability of antifreeze protein (AFP) type I to suppress ice recrystallization was numerical estimated and it was confirmed that ATP type I suppressed the ice recrystallization significantly at 1 μ g/mL. Searching for AFP from marine products in Tohoku region, the northeastern portion of Honshu, the largest island of Japan, was conducted. Among 21 species sold in local fisheries market, it was shown that 2 species, pacific cod ( Gadus microcephalus ) and marbled sole ( Pseudopleuronectes yokohamae ) had AFP. As for the AFP from pacific cod, seasonal change of AFP activity in the extract and effect of heating on AFP activity were also clarified.