Barmpalia-Davis Ioanna M, Geornaras Ifigenia, Kendall Patricia A, Sofos John N
Center for Meat Safety and Quality and Food Safety Cluster, Department of Animal Sciences, Colorado State University, Fort Collins, Colorado 80523, USA.
J Food Prot. 2008 Oct;71(10):2014-23. doi: 10.4315/0362-028x-71.10.2014.
Listeria monocytogenes counts were determined during storage (82 days, 4 degrees C) in vacuum packages of inoculated bologna and salami slices and after exposure to a simulated dynamic model of the stomach and small intestine. Variables controlled in the model included gastric emptying and gastrointestinal fluid secretion rates, gradual gastric acidification, and intestinal pH maintenance. L. monocytogenes populations increased on bologna and decreased on salami, reaching 8.7 and 1.4 log CFU/g, respectively, on day 82. Inactivation rates (IR) during gastric exposure of bologna and salami ranged from 0.079 (day 14) to 0.158 (day 57) log CFU/g/min and from 0.013 (day 42) to 0.051 (day 1) log CFU/g/min, respectively. On corresponding days, gastric IR for cells on salami were lower than on bologna, suggesting potential protective effects of the former product. However, it is also possible that the low initial L. monocytogenes levels reached with storage of salami (< or = 2.5 log CFU/g after day 27) may have resulted in slower reductions than in the high levels on bologna. Gradual decline of gastric pH allowed survival in the gastric compartment during the initial stages, which resulted in a large fraction of the cells being delivered into the intestinal compartment. Intestinal IR ranged from 0.003 to 0.048 (bologna) and from 0.002 to 0.056 (salami) log CFU/g/min throughout storage. Although findings indicated potential effects of salami against gastric killing of L. monocytogenes, any effects of the food matrix per se on the gastrointestinal survival of the pathogen were overwhelmed by the high and low contamination levels reached on bologna and salami, respectively, during storage.
在接种的博洛尼亚香肠和萨拉米香肠切片的真空包装储存期间（82天，4℃）以及暴露于胃和小肠的模拟动态模型后，测定了单核细胞增生李斯特菌的数量。模型中控制的变量包括胃排空和胃肠液分泌速率、胃酸逐渐酸化以及肠道pH维持。博洛尼亚香肠上的单核细胞增生李斯特菌数量增加，而萨拉米香肠上的数量减少，在第82天分别达到8.7和1.4 log CFU/g。博洛尼亚香肠和萨拉米香肠在胃暴露期间的灭活率（IR）分别为0.079（第14天）至0.158（第57天）log CFU/g/分钟和0.013（第42天）至0.051（第1天）log CFU/g/分钟。在相应的日子里，萨拉米香肠上细胞的胃IR低于博洛尼亚香肠，表明前一种产品具有潜在的保护作用。然而，也有可能萨拉米香肠储存后达到的低初始单核细胞增生李斯特菌水平（第27天后≤2.5 log CFU/g）导致其减少速度比博洛尼亚香肠上的高水平慢。胃酸pH的逐渐下降使得细胞在初始阶段能够在胃腔内存活，这导致大部分细胞被输送到肠道腔。在整个储存过程中，肠道IR范围为0.003至0.048（博洛尼亚香肠）和0.002至0.056（萨拉米香肠）log CFU/g/分钟。尽管研究结果表明萨拉米香肠对单核细胞增生李斯特菌有潜在保护作用，使其免受胃中的杀灭，但在储存期间，博洛尼亚香肠和萨拉米香肠分别达到的高污染水平和低污染水平，使得食品基质本身对该病原体在胃肠道存活的任何影响都被掩盖了。
