Center for Meat Safety & Quality and Food Safety Cluster, Department of Animal Sciences, Colorado State University, 1171 Campus Delivery, Fort Collins, CO 80523, USA.
Food Microbiol. 2010 Sep;27(6):783-90. doi: 10.1016/j.fm.2010.04.003. Epub 2010 Apr 13.
United States regulations require ready-to-eat meat and poultry processors to control Listeria monocytogenes using interventions which may include antimicrobials that reduce post-processing contamination by at least 1 log-cycle; if the treatment achieves > or = 2 log reductions, the plant is subject to less frequent microbial testing. Lactic acid (LA) may be useful as a post-lethality intervention and its antimicrobial properties may increase with temperature of application. The aim of this study was to evaluate the effect of LA solution concentration and temperature on L. monocytogenes counts of inoculated frankfurters and to identify parameters (concentration, temperature, and time) that achieve 1 and 2 log-unit immediate reductions. Frankfurters were surface-inoculated with a 10-strain mixture of L. monocytogenes (4.4 +/- 0.1 log CFU/cm(2)) and then immersed in distilled water or LA solutions (0-3%) of 4, 25, 40, or 55 degrees C for 0-120 s. A regression equation for L. monocytogenes reduction included significant (P < 0.05) effects by the terms of concentration, time, temperature, and the interaction of concentration and temperature; other tested parameters (other interactions, quadratic and cubic terms), within the experimental range examined, did not affect (P > or = 0.05) the extent of reduction. Results indicated that the effectiveness of LA against L. monocytogenes, in addition to concentration, increased with solution temperature (in the range of 0.6-2.8 log CFU/cm(2)). The developed equation may allow processors to vary conditions of treatment with LA to achieve a 1 or 2 log-unit reduction of the pathogen and comply with United States regulations.
美国法规要求即食肉类和禽类加工商使用干预措施来控制李斯特菌，这些干预措施可能包括抗菌剂，使加工后污染减少至少 1 对数周期；如果处理可实现>或=2 对数减少，则该工厂的微生物检测频率较低。乳酸（LA）可用作致死后干预措施，其抗菌性能可能随应用温度而增加。本研究旨在评估 LA 溶液浓度和温度对接种法兰克福香肠中李斯特菌计数的影响，并确定实现 1 和 2 对数单位即时减少的参数（浓度、温度和时间）。法兰克福香肠用 10 株李斯特菌混合物（4.4 +/- 0.1 log CFU/cm(2))进行表面接种，然后浸入蒸馏水或 4、25、40 或 55°C 的 LA 溶液（0-3%）中 0-120 秒。李斯特菌减少的回归方程包括浓度、时间、温度以及浓度和温度之间相互作用的显著（P < 0.05）效应；在实验范围内测试的其他参数（其他相互作用、二次和三次项）对减少程度没有影响（P > or = 0.05)。结果表明，LA 对李斯特菌的有效性除了浓度外，还随溶液温度的升高而增加（在 0.6-2.8 log CFU/cm(2)范围内）。所开发的方程可允许加工商改变 LA 处理条件，以实现病原体减少 1 或 2 对数单位，并符合美国法规。
