PURPOSE: To prepare a bean curd having improved taste, low odor and high nitritive value and suitable for the prevention of aging, by kneading seasoned calcium and nucleic acid powder with water, adding the kneaded mixture to soya milk and stirring the milk mixture.

CONSTITUTION: Soybean is immersed in water, crushed with a mixer and heated at about 108°C. The treated soybean is squeezed and separated into soya milk and bean curd refuse. Separately, meal of boiled and dried sardine and nucleic acid powder are kneaded with water and the kneaded mixture is slowly added to the soya milk under stirring. The objective bean curd can be prepared by adding bittern (magnesium chloride) to the soya milk mixture. The nucleic acid mixture used in the above process is DNA and RNA extracted from cell nucleus and has excellent effect to prevent aging, etc. It includes vegetable-based nucleic acid derived from unpolished rice, etc., and animal-based nucleic acid derived from soft roe of fish, etc. The use of the meal of boiled and dried sardine is effective in obtaining a bean curd containing a raw material for soup.