| 摘要 |
PURPOSE:To contrive highly efficient drying, by setting a ceramic radiation material having improved far infrared ray radiation characteristics in a drying chamber kept at high vacuum and sublimating water from a frozen food by radiation heat from the heated ceramic radiation material. CONSTITUTION:A ceramic radiation material 2 is prepared by calcining an alumina, magnesia or zirconia ceramic or a composite material thereof or from mullite. Then, the ceramic radiation material having improved far infrared radiation characteristics is set in a drying chamber 1 kept at high vacuum. The temperature of the radiation material 2 is raised and water is sublimated from a pure ice phase of a frozen food by radiation heat from the radiation material 2. Consequently, the temperature of the frozen food is uniformly raised, latent heat of sublimation can be directly fed to a frozen layer and evaporation rate can be raised while suppressing the temperature of the food to a low temperature. Freeze drying with reduced energy can be carried out in improved restoration properties and in high efficiency without damaging flavor of vegetables, fish meat, etc.
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