title: Sanitizing radish seeds by simultaneous treatments with gaseous chlorine dioxide, high relative humidity, and mild heat.
abstract: Sanitizing radish seeds intended for edible sprout production was achieved by applying simultaneous treatments with gaseous chlorine dioxide (ClO2), high relative humidity (RH, 100%), and mild heat (55°C). Gaseous ClO2was produced from aqueous ClO2(0.66ml) by mixing sulfuric acid (5% w/v) with sodium chlorite (10 mg/mL) in a sealed container (1.8L). Greater amounts of gaseous ClO2were measured at 23% RH (144ppm after 6h) than at 100% RH (66ppm after 6h); however, the lethal activity of gaseous ClO2against naturally occurring mesophilic aerobic bacteria (MAB) on radish seeds was significantly enhanced at 100% RH. For example, when exposed to gaseous ClO2at 23% RH, the number of MAB on radish seeds decreased from 3.7logCFU/g to 2.6logCFU/g after 6h. However, when exposed to gaseous ClO2at 100% RH for 6h, the MAB population decreased to 0.7logCFU/g after 6h. Gaseous ClO2was produced in higher amounts at 55°C than at 25°C, but decreased more rapidly over time at 55°C than at 25°C. The lethal activity of gaseous ClO2against MAB on radish seeds was greater at 55°C than at 25°C. When radish seeds were treated with gaseous ClO2(peak concentration: 195ppm) at 100% RH and 55°C, MAB were reduced to populations below the detectable level (<-0.7logCFU/g) within 2h without decreasing the seed germination rate (97.7%). The lethality of combined treatments against artificially inoculated Escherichia coli O157:H7 was also evaluated. When exposed to gaseous ClO2at 100% RH and 55°C for 6h, the initial number of E. coli O157:H7 (3.5logCFU/g) on radish seeds decreased to below the detection limit (0.7logCFU/g) by direct plating but it was not eliminated from seeds. The germination rate of radish seeds was not significantly (P>0.05) decreased after treatment for 6h. The information reported here will be useful when developing decontamination strategies for producing microbiologically safe radish seed sprouts.
authors: Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea.
authors: Jihyun
authors: J
authors: Bang
authors: Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea.
authors: Moonhak
authors: M
authors: Choi
authors: Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea.
authors: Hyeri
authors: H
authors: Son
authors: Center for Food Safety and Department of Food Science and Technology, University of Georgia, 1109 Experiment Street, Griffin, Georgia 30223-1797, USA.
authors: Larry R
authors: LR
authors: Beuchat
authors: Korea Food Research Institute, baekhyun-dong, Seongnam, Gyeonggi 463-746, Republic of Korea.
authors: Yoonsook
authors: Y
authors: Kim
authors: Department of Food and Nutrition, Wonkwang University, 460 Iksandae-ro, Iksan, Jeonbuk 54538, Republic of Korea. Electronic address: hoikyung@wku.ac.kr.
authors: Hoikyung
authors: H
authors: Kim
authors: Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea. Electronic address: escheri@korea.ac.kr.
authors: Jee-Hoon
authors: JH
authors: Ryu
mesh_terms: D002713:Chlorine / Q000494:pharmacology; D017606:Chlorine Compounds / Q000494:pharmacology*; D015169:Colony Count, Microbial; D003666:Decontamination; D004202:Disinfectants / Q000494:pharmacology*; D019453:Escherichia coli O157 / Q000254:growth & development*; D005506:Food Contamination / Q000517:prevention & control*; D005516:Food Microbiology; D005740:Gases; D018525:Germination; D006358:Hot Temperature; D006813:Humidity; D010087:Oxides / Q000494:pharmacology*; D031224:Raphanus / Q000382:microbiology*; D012639:Seeds / Q000382:microbiology
chemical_list: D017606:Chlorine Compounds; D004202:Disinfectants; D005740:Gases; D010087:Oxides; D002713:Chlorine; C025109:chlorine dioxide
keywords: Escherichia coli O157:H7; Gaseous chlorine dioxide; High relative humidity; High temperature; Mesophilic aerobic bacteria; Radish seed; Radish sprouts; Sanitizer