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Survival and growth of Escherichia coli O157:H7 inoculated onto cut lettuce before or after heating in chlorinated water, followed by storage at 5 or 15 °C.

Author(s) : LI Y., BRACKETT R. E., CHEN J., et al.

Type of article: Article

Summary

This study determined the effects of mild heat and chlorine treatment followed by storage for up to 18 days at 5 °C or 7 days at 15 °C on the survival and growth of Escherichia coli O157:H7 inoculated onto fresh-cut iceberg lettuce. The efficacy of treatment with 20 ppm chlorine in killing the pathogen on lettuce at 50 °C was determined. Treatment of lettuce with 20 ppm chlorine at either 20 or 50 °C did not result in significantly greater reductions in populations of E. coli O157:H7 compared to respective treatments in water alone. The pathogen steadily decreased in viability on treated lettuce throughout subsequent storage at 5 °C for 18 days. The population increased by 2.3 to 3.2 log(10) CFU/g within 2 days, then continued to increase at a slower rate through 7 days of storage at 15 °C. At 4 and 7 days, significantly higher populations were reached on lettuce that had been treated at 50 °C, compared to respective samples that had been treated at 20 °C, regardless of the presence of 20 ppm chlorine in the treatment water. Treatment of lettuce with 20 ppm chlorine at 50 or 20 °C before or after inoculation with E. coli O157:H7 did not have a marked influence on behavior of the pathogen during subsequent storage at 5 or 15 °C.

Details

  • Original title: Survival and growth of Escherichia coli O157:H7 inoculated onto cut lettuce before or after heating in chlorinated water, followed by storage at 5 or 15 °C.
  • Record ID : 2001-2788
  • Languages: English
  • Source: Journal of Food Protection - vol. 64 - n. 3
  • Publication date: 2001/03
  • Document available for consultation in the library of the IIR headquarters only.

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