Patent ID: 8114452

Claim:
A microwavable vacuum-packed frozen sushi product configured for controlled thawing of a frozen sushi food contained therein, to 10° C. to 30° C., comprising: a flexible plastic packing bag which is vacuumed to a pressure of 150 to 350 mmHg and, in the pressure-reduced state, hermetically sealed; an open-topped plastic box, the top opening of which is formed so as to be broader than a bottom of the plastic box, placed in the plastic packing bag; a laminated metal foil placed on the bottom of the plastic box; and a frozen sushi food product which is formed by at least one shaped form of frozen boiled rice and a frozen sushi food material or sushi food materials on a surface of each form of at least one shaped form of frozen boiled rice, placed on the laminated metal foil and having its sushi food material or sushi food materials in contact with the laminated metal foil, the microwaveable vacuum-packed frozen sushi product being configured to substantially prevent the frozen sushi food material from being cooked by microwaves to a temperature above 40° C. when the hermetically sealed frozen sushi product is microwaved and wherein the frozen boiled rice is configured to be cooked by microwaves to a temperature of at least 50° C., on an end portion surface thereof, to generate heated water vapor; the microwavable vacuum-packed frozen sushi product being configured such that microwave heating of the frozen sushi food product heats an end portion surface of the frozen boiled rice to a temperature of at least 50° C., at which time the frozen sushi food product is removed from the microwave heating and wherein the heated rice provides heated water vapor which substantially evenly heats and thaws the sushi food material to a temperature between 10° C. and 30° C., the microwaveable vacuum-packed frozen sushi product being configured to provide the thawing of the sushi food material with an inner surface of the plastic packing bag being in contact with a rice section of the sushi food product; and the plastic packing bag, the plastic box, the laminated metal foil and the sushi food product being frozen together in a unified form; and with an empty space being formed around the sushi food product in the hermetically sealed packing bag in the pressure-reduced state having a volume 0.2 to 0.5 times that of the sushi food product, the volume of empty space being configured to permit the substantially even steam heating of the sushi food material by the heated water vapor emanating from the shaped rice section and flowing into the empty space between the sushi product and box after microwave heating of the frozen boiled rice is terminated, thereby steaming the shaped rice section and the sushi food material or sushi food materials to a temperature, between 10° C. and 30° C.