PURPOSE: To produce a heated and processed food having enormously improved shelf stability, by blending a food raw material with a fermented solution of red KOJI or a purified solution thereof, heating and processing.

CONSTITUTION: In producing sauce for pizza, soup, boiled noodles, fish meat paste or other heated and processed foods, a fermented solution of red KOJI or a purified solution thereof such as supernatant liquid of the fermented solution of red KOJI is treated with active carbon and then filtered to give filtrate or a concentrated solution obtained by condensing the filtrate, which is incorporated with ethanol to remove insoluble substances. Ethanol is distilled away and the residue is dialyzed with water to give a solution, which is mixed with a food raw material and the food raw material is then heated and processed by a conventional procedure.