PURPOSE: To obtain the title food good in nutrient balance with small discoloration and denaturation with utilization of surplus agricultural products, process residues etc., by adding to a food a unicellular suspension in the form of gruel produced by acting a specific enzyme on a plant.

CONSTITUTION: An enzyme capable of converting plant tissue to single cells is acted, at a proper pH, on a plant to degrade its intercellular substances into single cells in the form of gruel, and undhgraded substances are removed, thus producing a unicellular suspension in the form of gruel. This suspension is then added to a food to obtain the objective food. It is preferable that a unicellular paste produced by dehydrating said suspension or a dried product from the paste be added to a food.