Survival of Listeria monocytogenes on cooked and high pressure treated bacon

Abstract

This study determined the survival of Listeria monocytogenes on cooked, high pressure processed (HPP) bacon strips and bits during a 150-day storage period at 4°C. Bacon strips and bits with two aw levels at ≤0.81 and ≥0.82 were inoculated with L. monocytogenes at 2.0 log CFU/g and high pressure processed at 86,000 psi for 5 min. Samples were then stored at 4°C and analyzed for 150 days. Triangle testing was performed concurrently to determine if flavor differences existed between un-inoculated HPP and non-HPP samples. There were no significant differences in L. monocytogenes populations between bacon strips and bits or between samples with different aw. HPP resulted in an initial decrease (measured at 24 hours) of 0.3 log CFU/g compared to non-HPP samples. The L. monocytogenes population declined over the course of 150 days in non-HPP samples by 0.4 log CFU/g but did not significantly decline over time in the HPP bacon. HPP and non-HPP bits and low aw strips were not statistically different in flavor. The higher aw strips, however, were statistically different, with up to 31% of the test population able to discern between HPP and non-HPP product. These data suggest that HPP is only slightly effective in reducing L. monocytogenes populations in cooked bacon strips and bits. Thus, the high cost of HPP may not be justified for Listeria control in cooked bacon.

Keywords

• Ready-to-eat
• High pressure processing
• Bacon bits
• Bacon strips, L. monocytogenes