Dynamics of Radioactive Cesium during Noodle Preparation and Cooking of Dried Japanese Udon Noodles

We investigated the dynamics of radioactive cesium (Cs-134 plus(137)Cs) during preparation and cooking of dried Japanese udon noodles (dried noodles). Dried noodles are prepared by drying treatment of fresh noodles. The radioactive cesium in the dried noodles, boiled noodles, broth and rinse water were measured with a germanium semiconductor detector. Processing factor (Pf, ratio of radioactive cesium concentration in processed materials to raw materials) and food processing retention factor (Fr, ratio of residual radioactive cesium content in processed materials to raw materials) were calculated. Concentrations of radioactive cesium did not show significant differences ( < 0.05) between flour and dried noodles. The Pf values for thick noodles (1.8 mm X 3 mm) and thin noodles (1.1 mm in diameter) were 0.935 and 0.977, respectively. On the other hand, the Pf values for boiled thick noodles and boiled thin noodles were 0.063 and 0.038, respectively. Greater than 80% of the radioactive cesium contained in the raw noodles was removed from the thick noodles and thin noodles during boiling for 15 min and 3 min, respectively. The drying treatment during noodle preparation of dried noodles may have no effect on the removal of radioactive cesium by cooking, because these removal percentages corresponded well with those of fresh noodles reported in our previous study. An increase in boiling water volume contributed to a significant decrease (p < 0.05) of radioactive cesium concentration, although both pH and hardness of water had no significant effects (p > 0.05) on the dynamics of radioactive cesium during cooking.