| 摘要 |
PROBLEM TO BE SOLVED: To preserver food while suppressing degradation by providing a storage compartment, i.e., a new temperature zone freezing compartment, having a temperature zone lower than a maximum ice crystal generation zone but higher than the freezing temperature zone, thereby prolonging the preservation period of food as compared with an ice temperature compartment. SOLUTION: Relationship between the preservation temperature and the reaction rate, i.e., the extent (met-myoglobin-ization) of variation in the surface color of food, is shown. The ordinate shows the reaction rate of met-myoglobin-ization and the abscissa shows the preservation temperature of food. The reaction rate of met- myoglobin-ization is highest in the maximum crystal generation zone from -1 deg.C to -5 deg.C where moisture in the food begins to freeze and an unstable state easily causing degradation of feed is brought about and the surface color is degraded. In other words, cells of the food are damaged and the taste is degraded. In order to preserve a food while avoiding the maximum crystal generation zone, temperature of a new temperature zone freezing zone freezing compartment is set at -5 deg.C or below. Since a long time is required for thawing in the freezing temperature zone (-18 deg.C or below) although the preservation time is long, the temperature is set at -15 deg.C or above in order to preserve food while avoiding the freezing temperature. |
