Lianou Alexandra, Geornaras Ifigenia, Kendall Patricia A, Scanga John A, Sofos John N
Center for Red Meat Safety, Department of Animal Sciences, Colorado State University, Fort Collins, CO 80523-1171, USA.
Food Microbiol. 2007 Aug;24(5):433-43. doi: 10.1016/j.fm.2006.11.002. Epub 2007 Jan 5.
Uncured turkey breast, commercially available with or without a mixture of potassium lactate and sodium diacetate, was sliced, inoculated with a 10-strain composite of Listeria monocytogenes, vacuum-packaged, and stored at 4 degrees C, to simulate contamination after a lethal processing step at the plant. At 5, 15, 25 and 50 days of storage, packages were opened, slices were tested, and bags with remaining slices were reclosed with rubber bands; this simulated home use of plant-sliced and -packaged product. At the same above time intervals, portions of original product (stored at 4 degrees C in original processing bags) were sliced and inoculated as above, and packaged in delicatessen bags, simulating contamination during slicing/handling at retail or home. Both sets of bags were stored aerobically at 7 degrees C for 12 days to simulate home storage. L. monocytogenes populations were lower (P<0.05) during storage in turkey breast containing a combination of lactate and diacetate compared to product without antimicrobials under both contamination scenarios. Due to prolific growth of the pathogen under the plant-contamination scenario in product without lactate-diacetate during vacuum-packaged storage (4 degrees C), populations at 3 days of aerobic storage (7 degrees C) of such product ranged from 4.6 to 7.4 log cfu/cm(2). Under the retail/home-contamination scenario, mean growth rates (log cfu/cm(2)/day) of the organism during aerobic storage ranged from 0.14 to 0.16, and from 0.25 to 0.51, in product with and without lactate-diacetate, respectively; growth rates in turkey breast without antimicrobials decreased (P<0.05) with age of the product. Overall, product without antimicrobials inoculated to simulate plant-contamination and product with lactate-diacetate inoculated to simulate retail/home-contamination were associated with the highest and lowest pathogen levels during aerobic storage at 7 degrees C, respectively. However, 5- and 15-day-old turkey breast without lactate-diacetate stored aerobically for 12 days resulted in similar pathogen levels (7.3-7.7 log cfu/cm(2)), irrespective of contamination scenario.
未加工的火鸡胸肉，市售的有或没有乳酸钾和双乙酸钠混合物，被切片，接种单核细胞增生李斯特菌的10菌株复合物，真空包装，并储存在4℃，以模拟工厂致命加工步骤后的污染情况。在储存5、15、25和50天时，打开包装，对切片进行检测，装有剩余切片的袋子用橡皮筋重新封好；这模拟了家庭使用工厂切片和包装产品的情况。在上述相同的时间间隔，将部分原始产品（在原始加工袋中储存在4℃）按上述方法切片、接种，并包装在熟食袋中，模拟零售或家庭切片/处理过程中的污染。两组袋子都在7℃有氧储存12天以模拟家庭储存。在两种污染情况下，与不含抗菌剂的产品相比，含有乳酸和双乙酸组合的火鸡胸肉在储存期间单核细胞增生李斯特菌数量较低（P<0.05）。由于在真空包装储存（4℃）期间，不含乳酸 - 双乙酸的产品在工厂污染情况下病原体大量生长，此类产品在有氧储存3天（7℃）时的数量范围为4.6至7.4 log cfu/cm²。在零售/家庭污染情况下，有氧储存期间该微生物的平均生长速率（log cfu/cm²/天）在含乳酸 - 双乙酸和不含乳酸 - 双乙酸的产品中分别为0.14至0.16和0.25至0.51；不含抗菌剂的火鸡胸肉中的生长速率随产品存放时间增加而降低（P<0.05）。总体而言，模拟工厂污染接种的不含抗菌剂的产品和模拟零售/家庭污染接种的含乳酸 - 双乙酸的产品分别在7℃有氧储存期间与最高和最低病原体水平相关。然而，5天和15天的不含乳酸 - 双乙酸的火鸡胸肉有氧储存12天导致类似的病原体水平（7.3 - 7.7 log cfu/cm²），与污染情况无关。
