Microbial Food Safety Research Unit, Eastern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, Pennsylvania 19038, USA.
J Food Prot. 2005 Aug;68(8):1628-34. doi: 10.4315/0362-028x-68.8.1628.
This study examined and modeled the behavior of Listeria monocytogenes in ham salad and potato salad as affected by the pH of mayonnaise and storage temperature. An eight-strain cocktail of L. monocytogenes was inoculated on the surface of diced cooked ham or potato. The inoculated ham or potato was then mixed with regular mayonnaise (pH 3.8) or mayonnaise that was adjusted with NaOH to pH 4.2 or 4.6. The cell counts of L. monocytogenes in the salads during storage at 4, 8, or 12 degrees C were enumerated and used to model the behavior of L. monocytogenes in ham salad or potato salad. At each of the storage temperatures, L. monocytogenes was able to grow in ham salad, whereas L. monocytogenes was inactivated in potato salad. The growth rate (log CFU per hour) in ham salad or the inactivation rate (log CFU per hour) in potato salad increased as the storage temperature increased. The duration before growth in ham salad or inactivation in potato salad increased as storage temperature decreased. The mayonnaise pH showed no consistent effect on the growth rate or inactivation rate and duration before growth or inactivation occurred. Mathematical equations that described the growth rate or inactivation rate of L. monocytogenes in both salads as a function of mayonnaise pH and storage temperature were generated and shown to be satisfactory in describing the growth rate or inactivation rate of L. monocytogenes in the ham salad or potato salad.
本研究考察并建立了模型，以研究 pH 值为 3.8 的蛋黄酱和 pH 值分别为 4.2、4.6 的经 NaOH 调节的蛋黄酱对李斯特菌在火腿沙拉和土豆沙拉中行为的影响。将八种李斯特菌混合的鸡尾酒接种到切丁的熟火腿或土豆表面。然后，将接种的火腿或土豆与普通蛋黄酱（pH 值为 3.8）或用 NaOH 调节 pH 值为 4.2 或 4.6 的蛋黄酱混合。在 4、8 或 12°C 下储存时，对沙拉中李斯特菌的细胞计数进行了计数，并用于建立模型来模拟李斯特菌在火腿沙拉或土豆沙拉中的行为。在每个储存温度下，李斯特菌都能在火腿沙拉中生长，而李斯特菌在土豆沙拉中失活。在火腿沙拉中的生长速度（每小时 CFU 对数）或在土豆沙拉中的失活速度（每小时 CFU 对数）随储存温度的升高而增加。在火腿沙拉中生长或在土豆沙拉中失活之前的时间随储存温度的降低而增加。蛋黄酱的 pH 值对生长速度或失活速度以及生长或失活之前的时间没有一致的影响。生成了描述两种沙拉中李斯特菌生长速度或失活速度与蛋黄酱 pH 值和储存温度之间关系的数学方程，结果表明，这些方程能够很好地描述李斯特菌在火腿沙拉或土豆沙拉中的生长速度或失活速度。
