Deaerated packaged frozen sushi, process for producing the same and method of cooking

A microwavable vacuum-packed frozen sushi product, configured for controlled thawing of a frozen sushi food material or frozen sushi food materials contained therein, the frozen sushi product containing a rice section, the frozen sushi product being configured to be thawed by means of a microwave oven which elevates a temperature of an end portion on a surface of the rice section to 50° C. and higher, the frozen sushi product comprising:

• a microwavable flexible plastic packing bag which is vacuumed to a pressure of 140 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 said plastic packing bag;
• and
• a frozen sushi food product which is formed by at least one shaped form of frozen boiled rice and the frozen sushi material or sushi food materials on a surface of each form of at least one shaped form of the frozen boiled rice, placed on the bottom of the box;
• the microwavable vacuum-packed frozen sushi product being configured such that microwave heating of the frozen sushi food product heats an end portion on a surface of the rice section 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 or sushi food materials to a temperature between 15° and 30° C., the microwavable vacuum-packed frozen sushi product being configured to provide the thawing of the sushi food material or sushi food materials with an inner surface of the plastic packing bag, the plastic box, and the sushi food product being frozen together in a unified form;
• and
• an empty space being allowed to remain in said hermetically sealed packing bag in the pressure-reduced state around said sushi food product with the empty space having a volume 0.2 to 0.5 times that of a volume of said sushi food product at the time of thawing, and the empty space in the hermetically sealed packing bag being configured to allow heating of the sushi product by steam emanating at least from the shaped rice section and flowing into the empty space between the sushi product and the box, after the elevation of the temperature of the rice section by means of the microwave oven and termination of the microwave heating thereby steaming the shaped rice section and the sushi food material or sushi food materials to a temperature between 15° and 30° C.