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Survival of Escherichia coli O157:H7 in Cucumber Fermentation Brines

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Bacterial pathogens have been reported on fresh cucumbers and other vegetables used for commercial fermentation. The Food and Drug Administration currently has a 5-log reduction standard for E. coli O157:H7 and other vegetative pathogens in acidified pickle products. For fermented vegetables, which are acid foods, there is little data documenting the conditions needed to kill acid resistant pathogens. To address this knowledge gap, we obtained 10 different cucumber fermentation brines at different stages of fermentation from 5 domestic commercial plants. Cucumber brines were used to represent vegetable fermentations because cabbage and other vegetables may have inhibitory compounds that may affect survival. The 5-log reduction times for E. coli O157:H7 strains in the commercial brines were found to be positively correlated with brine pH, and ranged from 3 to 24 d for pH values of 3.2 to 4.6, respectively. In a laboratory cucumber juice medium that had been previously fermented with Lactobacillus plantarum or Leuconostoc mesenteroides (pH 3.9), a 5-log reduction was achieved within 1 to 16 d depending on pH, acid concentration, and temperature. During competitive growth at 30 °C in the presence of L. plantarum or L. mesenteroides in cucumber juice, E. coli O157:H7 cell numbers were reduced to below the level of detection within 2 to 3 d. These data may be used to aid manufacturers of fermented vegetable products determine safe production practices based on fermentation pH and temperature.
Breidt, Frederick Jr. , Caldwell, Jane M.
fermentation industry , plate count , cucumbers , dill , fermented foods , fermentation , brining , Escherichia coli O157:H7 , food pathogens , acid tolerance , acidification , pickles , pickled vegetables , food contamination , vegetable juices , Lactobacillus plantarum , Leuconostoc mesenteroides , lactic acid bacteria , temperature , heat tolerance , competitive exclusion , food safety
p. M198-M203.
Includes references
Journal of food science: an official publication of the Institute of Food Technologists 2011 Apr., v. 76, no. 3
Journal Articles, USDA Authors, Peer-Reviewed
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