Cetylpyridinium Chloride for Destruction or Control of Listeria Monocytogenes or Escherichia coli 0157:H7 Inoculated onto the Surfaces of Whole and Chopped Vegetables. M. E. Janes and M. G. Johnson, University of Arkansas
Cetylpyridinium chloride (CPC) was tested for its ability to reduce or kill Listeria monocytogenes (Lm) or enterohemorrhagic Escherichia coli 0157:H7 (EHEC) freshly inoculated onto the surfaces of whole or chopped vegetables or inoculated and allowed to grow at 25°C for 0 to 4 days or 8°C for 0 to 8 days. Surface sterilized whole or chopped bell peppers, spinach, iceberg lettuce and cabbage samples (25 g) were inoculated with decimally diluted 16 h broth cultures of Lm or EHEC for 1 min, rinsed with different CPC concentrations (0.05, 0.1, 0.2, 0.4, 0.6, 0.8 or 1%) for 1 min, then rinsed with water for 1 min, and the CFU/g determined. For freshly inoculated chopped lettuce only 0.2% CPC was needed to reduce a 5.6 log inoculum of Lm to non-detectable levels whereas 0.8% CPC was needed to cause the same reductions of EHEC counts. For pre-adapted bacteria on chopped lettuce, a 0.05% CPC rinse solution gave a 2 log reduction of Lm counts at day 0 but only 1 log reductions by day 4 at 25°C or day 8 at 8°C, as compared to controls. Conversely, CPC rinses reduced EHEC counts by 2 logs at both adaption temperatures over 4 to 8 days, compared to controls. CPC gave a more significant reduction of EHEC counts attached to whole or chopped lettuce compared to EHEC reductions on the other vegetables tested. The 0.2% CPC rinses were more likely to reduce L. monocytogenes counts to non-detectable levels for the chopped verse the whole un-chopped produce. Our results suggest CPC rinse treatments can provide raw produce processors with a control measure to help reduce or eliminate normal levels of foodborne pathogens from produce.
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