Sanitizing radish seeds by simultaneous treatments with gaseous chlorine dioxide, high relative humidity, and mild heat

Jihyun Bang, Moonhak Choi, Hyeri Son, Larry R. Beuchat, Yoonsook Kim, Hoikyung Kim, Jee-Hoon Ryu

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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 ClO2 was produced from aqueous ClO2 (0.66 ml) by mixing sulfuric acid (5% w/v) with sodium chlorite (10 mg/mL) in a sealed container (1.8 L). Greater amounts of gaseous ClO2 were measured at 23% RH (144 ppm after 6 h) than at 100% RH (66 ppm after 6 h); however, the lethal activity of gaseous ClO2 against naturally occurring mesophilic aerobic bacteria (MAB) on radish seeds was significantly enhanced at 100% RH. For example, when exposed to gaseous ClO2 at 23% RH, the number of MAB on radish seeds decreased from 3.7 log CFU/g to 2.6 log CFU/g after 6 h. However, when exposed to gaseous ClO2 at 100% RH for 6 h, the MAB population decreased to 0.7 log CFU/g after 6 h. Gaseous ClO2 was 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 ClO2 against MAB on radish seeds was greater at 55 °C than at 25 °C. When radish seeds were treated with gaseous ClO2 (peak concentration: 195 ppm) at 100% RH and 55 °C, MAB were reduced to populations below the detectable level (<−0.7 log CFU/g) within 2 h 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 ClO2 at 100% RH and 55 °C for 6 h, the initial number of E. coli O157:H7 (3.5 log CFU/g) on radish seeds decreased to below the detection limit (0.7 log CFU/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 6 h. The information reported here will be useful when developing decontamination strategies for producing microbiologically safe radish seed sprouts.

Original languageEnglish
Pages (from-to)150-156
Number of pages7
JournalInternational Journal of Food Microbiology
Publication statusPublished - 2016 Nov 21



  • Escherichia coli O157:H7
  • Gaseous chlorine dioxide
  • High relative humidity
  • High temperature
  • Mesophilic aerobic bacteria
  • Radish seed
  • Radish sprouts
  • Sanitizer

ASJC Scopus subject areas

  • Food Science
  • Microbiology
  • Medicine(all)
  • Safety, Risk, Reliability and Quality

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