Department of Food Hygiene and Consumer Health Protection, Wrocław University of Environmental and Life Sciences, Wrocław, Poland.
Foodborne Pathog Dis. 2011 Jul;8(7):839-41. doi: 10.1089/fpd.2010.0790. Epub 2011 Mar 7.
The effect of a 54°C heat exposure lasting 20 and 60 minutes on the invasiveness of 10 Listeria monocytogenes strains in the exponential and stationary phases was investigated. It was shown that heat exposure significantly reduced the L. monocytogenes count. A maximal reduction of 5 log took place after 60 minutes of heating. No significant differences in survival between exponential and stationary phases were observed for most strains. Twenty minutes of heat exposure resulted in a reduction of the invasiveness of L. monocytogenes, which was more pronounced in the exponential-phase bacteria. Prolongation of heating to 60 minutes was shown to have a significant impact on the invasiveness of five stationary-phase strains. It was demonstrated that heat exposure influences the survival of L. monocytogenes strains as expected. Also, the invasiveness was significantly changed in a time- and growth phase-dependent manner. Low reductions of bacterial counts in milder conditions, that is, 20 minutes of heat, were accompanied by a decrease of the invasiveness of all L. monocytogenes strains. Prolongation of heating time to 60 minutes resulted in significant reduction of bacterial numbers. However, bacteria, especially those in the stationary phase, which survived this treatment can become more invasive.
研究了 54°C 热暴露持续 20 和 60 分钟对指数期和静止期 10 株李斯特菌侵袭力的影响。结果表明，热暴露显著降低了李斯特菌的数量。60 分钟加热后，最大减少了 5 个对数级。大多数菌株在指数期和静止期的存活没有显著差异。20 分钟的热暴露导致李斯特菌的侵袭力降低，在指数期细菌中更为明显。延长加热至 60 分钟对五株静止期菌株的侵袭力有显著影响。结果表明，热暴露对李斯特菌菌株的存活有预期的影响。此外，侵袭力也以时间和生长阶段依赖的方式发生显著变化。在较温和的条件下（即 20 分钟的热暴露），细菌数量的低减少伴随着所有李斯特菌菌株侵袭力的降低。延长加热时间至 60 分钟会导致细菌数量的显著减少。然而，在此处理后存活的细菌，特别是那些处于静止期的细菌，可能会变得更具侵袭性。
