The Effect of Calcinated Calcium and Chlorine Treatments on Escherichia coli O157:H7 87-23 Population Reduction in Radish Sprouts

Lilia Fransisca, Bin Zhou, Heekyung Park, Hao Feng

Research output: Contribution to journalArticlepeer-review

Abstract

The effect of calcinated calcium spray onEscherichia coliO157:H7 87-23 population reduction during radish sprout production was studied. Artificially inoculated radish seeds were soaked in sodium hypochlorite (NaOCl) solutions (200 and 20000 ppm), rinsed in distilled water, and sprayed with water or a calcinated calcium solution during sprouting. Microbial plate count was obtained at each step of the process and germination rate was determined after 72 h of sprouting. Scanning electron microscopy (SEM) was done on treated seeds and sprouts to locate which parts were populated by theE. colicells. The results showed that the active compound in the calcinated calcium was calcium oxide. The treatment of 200 ppm NaOCl soaking followed by 0.04% calcinated calcium spray resulted in no microbial growth after a 72-h sprouting, while maintaining a high germination rate. The 0.4% calcinated calcium spray significantly reduced the germination rate and is therefore not recommended. Soaking the seeds in a 20000 ppm chlorine solution achieved the highestE. colicount reduction (1.65 log CFU/g). However, theE. colicells that survived the 20000 ppm chlorine soak grew to 6 log CFU/g sprouts after a 72-h sprouting, significantly higher than the initial count on the seeds. The SEM microimages showed that the bacteria were mostly located in the roots of the radish sprouts and all across the seed surface. TheE. coliO157:H7 87-23 cells appeared to be located in biofilms or embedded into the radish sprout tissues during sprouting.

Original languageEnglish (US)
Pages (from-to)M404-M412
JournalJournal of food science
Volume76
Issue number6
DOIs
StatePublished - Aug 1 2011

Keywords

  • Calcinated calcium
  • Calcium oxide
  • Escherichia coli
  • Germination
  • Radish sprout

ASJC Scopus subject areas

  • Food Science

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