Abstract
The effect of noodle size and boiling time on dynamics of radioactive cesium during cooking of Japanese udon noodles was investigated. Two noodle sizes, thick noodles (2.5 mm × 3 mm) and thin noodles (1.5 mm × 1.5 mm), were prepared and processing factor (Pf, ratio of radioactive cesium concentration in processed materials to raw materials, calculated by [concentration of boiled noodles (Bq/kg)/concentration of raw noodles (Bq/kg)]) and food processing retention factor (Fr, ratio of residual radioactive cesium content in processed materials to raw materials, calculated by [radioactive cesium content of boiled noodles (Bq)/radioactive cesium content of raw noodles (Bq)] ) at various boiling times were calculated. Both Pf and Fr were significantly decreased by boiling in both noodle sizes. Prolongation of boiling time contributed to decreases in Pf and Fr in both noodle sizes, although there were no significant decreases in Pf after 20 min in thick noodles and 4.5 min in thin noodles. In Fr, there were no significant decreases after 10 min and 3 min in thick and thin noodles, respectively. These data indicate that prolongation of boiling time contributes minimally to lowering of radioactive cesium due to the low concentration gradient of radioactive cesium between boiled noodles and broth when noodles are properly boiled for consumption, 20 min and 3-4.5 min for thick and thin noodles, respectively. Thin noodles achieved lowered radioactive cesium content in a short boiling time compared to thick noodles. Greater than 80 % of radioactive cesium contained in the raw noodles was removed by boiling for the proper time in both thick and thin noodles.
