RADIOISOTOPES

In order to obtain information about effects of the cooking process on the changes of concentration and amount of radioactive materials in foods, we determined the concentration of radioactive caesium in several foods such as beef, edible wild plants, blueberries and mushrooms, before and after cooking. Our results showed that drying after soaking in liquid seasoning and the removal of astringent taste were effective in removing radioactive caesium from foods. More than 80％ of radioactive caesium could be removed by these cooking methods. These results suggest that cooking processes such as boiling and soaking in liquid seasoning or water are effective to remove radioactive caesium from foods. Moreover, appropriate food additives such as baking soda were useful to promote the removal of radioactive caesium from foods. On the other hand, simple drying, jam making, grilling and tempura cooking could not remove radioactive caesium from foods. In addition, we showed that the concentration of radioactive caesium in foods was raised after simple drying, although the amount of radioactive caesium was unchanged. It would be necessary to monitor radioactive caesium concentration in processed foods because they might have undergone dehydration by cooking, which could result in concentrations exceeding regulatory levels.