title: The transfer of radioactive cesium and potassium from rice to sake.
abstract: Using rice grains contaminated with radioactive cesium ((134)Cs and (137)Cs) that was released by the Fukushima Daiichi Nuclear Power Plant Accident in March of 2011, we investigated the behaviors of the radioactive cesium and potassium (total K and (40)K) during sake brewing. Cesiumis a congener of K, and yeast cells have the ability to take up Cs using known K transporters. During rice polishing, the concentrations of radioactive Cs and K in the polished rice grains decreased gradually until a milling ratio (polished rice weight/brown rice weight) of 70% was reached. No significant changes were observed below this milling ratio. Sake was brewed on a small scale using the 70% polished rice. The transfer ratio of radioactive Cs to sake and to the sake cake was significantly different than the ratio of K. Approximately 36% and 23% of radioactive Cs in the polished rice was transferred to the sake and sake cake, respectively; however, 40% was removed by washing and steeping the rice grains. On the other hand, 25% and 40% of K in the polished rice was recovered in the sake and sake cake, respectively, and 35% was removed by washing and steeping the rice grains. From the present results, the concentration of radioactive Cs in sake would be 4 Bq/kg fresh weight, which is well below the regulation values (100 Bq/kg), even using brown rice containing 100 Bq/kg of radioactive Cs.
authors.affiliation: National Research Institute of Brewing, 3-7-1 Kagamiyama, Higashihiroshima 739-0046, Japan. okuda@nrib.go.jp
authors.forename: Masaki
authors.initials: M
authors.lastname: Okuda
authors.forename: Tomokazu
authors.initials: T
authors.lastname: Hashiguchi
authors.forename: Midori
authors.initials: M
authors.lastname: Joyo
authors.forename: Kaori
authors.initials: K
authors.lastname: Tsukamoto
authors.forename: Michiko
authors.initials: M
authors.lastname: Endo
authors.forename: Katsumi
authors.initials: K
authors.lastname: Matsumaru
authors.forename: Nami
authors.initials: N
authors.lastname: Goto-Yamamoto
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yamaoka
authors.forename: Kenji
authors.initials: K
authors.lastname: Suzuki
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Shimoi
mesh_terms: D000434:Alcoholic Beverages / Q000032:analysis*; D002586:Cesium / Q000032:analysis; D002588:Cesium Radioisotopes / Q000032:analysis*; D005506:Food Contamination / Q000032:analysis* / Q000517:prevention & control; D005511:Food Handling / Q000379:methods; D062406:Fukushima Nuclear Accident; D007564:Japan; D012275:Oryza / Q000737:chemistry*; D011188:Potassium / Q000032:analysis; D011197:Potassium Radioisotopes / Q000032:analysis*; D011834:Radiation Monitoring
chemical_list: D002588:Cesium Radioisotopes; D011197:Potassium Radioisotopes; D002586:Cesium; D011188:Potassium
keywords: Cesium; Food retention factor; Potassium; Rice; Sake brewing