Survival and growth of Listeria monocytogenes and Escherichia coli O157:H7 in ready-to-eat iceberg lettuce washed in warm chlorinated water

ddCut iceberg lettuce inoculated with Escherichia coli O157:H7 and Listeria monocytogenes before and after washing for 3 min in cold (4degreesC) and warm (47degreesC) water containing 100 mg/liter total chlorine was stored at 1 and 10degreesC in oxygen-permeable film packages (6,000 to 8,000 cc/m(2)/24 h). Cold chlorinated water was detrimental to the survival of E. coli O157: H7 and L monocytogenes at both storage temperatures. In contrast, washing in warm chlorinated water favored the growth of both pathogens in lettuce stored at 10degreesC. There was no evidence of a relationship between the magnitude of spoilage microflora and the fate of either bacterium.