Distribution of Radioactive Cesium (Cs-137) During Cooking of Rice Noodles with Different Firmness

The distribution of radioactive cesium (Cs-137) from noodles to broth during noodle cooking was investigated using rice noodles differing in firmness. The firmness of rice noodles was controlled by the gluten concentration, 5 %, 10 %, and 20 %, in rice powder. Processing factor (P-f, ratio of radioactive cesium concentration in processed materials to raw materials) and food processing retention factor (F-r, ratio of radioactive cesium amount in processed materials to raw materials) for Cs-137 and nine kinds of inorganic elements were calculated. Both P-f and F-r for boiled noodles containing 20 % gluten showed significantly (p<0.05) higher levels than those for noodles containing 5% gluten. A positive correlation was obtained between P-f and compressive force at 80 % deformation in boiled rice noodles. F-r, likewise, also showed a positive correlation with the compressive force. The specific adsorption of radioactive cesium to gluten itself was not detected. Increase of moisture content(% DW) in boiled noodles and the compressive force were negatively correlated. Moreover, both P-f and F-r also showed a negative correlation with the increase of moisture content in boiled noodles. From these results, the increase of moisture content in boiled noodles might be involved in the difference in the transfer ratio of radioactive cesium from noodles to broth, depending on the firmness of noodles. The distribution patterns of potassium and sodium were similar to those of radioactive cesium.