Abstract：
This study assessed the growth of Listeria monocytogenes in ready-to-eat (RTE) ham during storage under conditions simulating domestic practices with the intention to offer support in the elaboration of food safety policies that should better protect consumers against food poisoning at home. RTE ham, artificially contaminated at either medium (102-103 CFU/g) or high (104-105 CFU/g) concentration, was stored at both isothermal (4℃ in a refrigerator able to maintain a relatively constant temperature and 5℃ and 7℃ in a refrigerator with fluctuating temperature) and dynamic (5℃ and 7℃ with intermittent exposure to ambient temperature, e.g. 25℃) conditions. Under isothermal conditions, the increasing storage temperature determined a significantly increased (p < 0.05) capacity of L. monocytogenes to grow. The kinetic growth parameters were derived by fitting the Baranyi and Roberts model to the experimental data and, based on the maximum specific growth rates, it was estimated the temperature dependence of L. monocytogenes growth in RTE ham. At medium contamination level, sanitary risk time calculation revealed that, unlike storage at 5℃ and 7℃, storage at 4℃ of the RTE ham extends the time period during which the product is safe for consumption by ∼40 and 52%, respectively. However, the real temperature fluctuations included in the Monte Carlo simulations at low L. monocytogenes counts (1, 5 and 10 CFU/g) have shortened the safety margins. Stochastic models also proved to be useful tools for describing the pathogen\'s behavior when refrigeration of the RTE ham alternates with periods of ham being kept at room temperature, considered dynamic conditions of growth.
摘要：
这项研究评估了在模拟国内实践的条件下，即食（RTE）火腿中单核细胞增生李斯特菌的储存过程中的生长情况，旨在为制定食品安全政策提供支持，以更好地保护消费者免受家中食物中毒。RTE火腿，在中等（102-103CFU/g）或高（104-105CFU/g）浓度下人工污染，存储在等温（4℃在冰箱中能够保持相对恒定的温度和5℃和7℃在冰箱中波动的温度）和动态（5℃和7℃间歇暴露于环境温度，例如25℃)条件。在等温条件下，储存温度的升高决定了单核细胞增生李斯特菌生长能力的显著提高(p<0.05)。通过将Baranyi和Roberts模型拟合到实验数据，得出了动力学生长参数，根据最大特定增长率，估计RTE火腿中单核细胞增生李斯特菌生长的温度依赖性。在中等污染水平，卫生风险时间计算显示，与5℃和7℃储存不同，在4℃下储存RTE火腿，将产品安全消费的时间延长了40%和52%，分别。然而,蒙特卡洛模拟中包含的低单核细胞增多性李斯特菌计数(1,5和10CFU/g)的真实温度波动缩短了安全裕度.随机模型也被证明是描述病原体行为的有用工具，当RTE火腿的冷藏与火腿在室温下保存的时间交替时，考虑了生长的动态条件。
