PRESERVATION OF SOLID FOOD

PURPOSE:To maintain excellent qualities for a long period of time without carrying out conventional high-temperature sterilization for many hours by packing a solid food having high water activity and ethanol into a package and heat-treating by irradiation with microwave. CONSTITUTION:A solid food having >=0.85 water activity and ethanol are packed into a package equipped with an opening part, preliminarily heat-treated by irradiation with microwave and the package is evacuated in vacuum. Then an inert gas is introduced into the package, the interior of the package is replaced with the inert gas, the opening part of the package is hermetically sealed and the solid food is heat-treated by irradiation with microwave. In packing the solid food and ethanol into the package, both the solid food and ethanol are separately fed into the package or ethanol is added to the solid during preparation of the solid food to give an ethanol-containing solid food, which may be packed into the package. Gas concentration of ethanol in the package is preferably set to 0.17-0.8vol.% after the heat treatment by irradiation with microwave.