Growth or Survivial of Listeria monocytogenes in Ready-to-Eat Meat Products and Combination Deli Salads During Refrigerated Storage

Growth or survival of Listeria monocytogenes in cold smoked salmon; sliced, cooked ham; sliced, roasted turkey; shrimp salad; and coleslaw obtained at retail supermarkets stored at 5degreesC, 7degreesC or 10degreesC (41degreesF, 45degreesF or 50degreesF respectively) for up to 14 d was evaluated. Cold smoked salmon, ham, and turkey were obtained in case ready, vacuum packages. All food products were stored aerobically to reflect additional handling within the retail supermarket. Cold smoked salmon, ham, and turkey supported the growth of L. monocytogenes at all 3 storage temperatures. Fitted growth curves of initial populations (about 3 log10 colony forming units [CFU]/g) in cold smoked salmon, ham, and turkey stored at 5degreesC achieved maximal growth rates of 0.29, 0.45, and 0.42 log10 CFU/g growth per day, respectively. Storage at 10degreesC increased the estimated maximal growth rate of the pathogen by 0.56 to 1.08 log10 CFU/g growth per day compared with storage at 5 degreesC. A decline in populations of L. monocytogenes was observed in shrimp salad and coleslaw, and the rate of decline was influenced by storage temperature. Retention of viability was higher in shrimp salad than in coleslaw, where populations fell 1.2, 1.8, and 2.5 log10 CFU/g at 5 degreesC, 7degreesC and 10degreesC respectively, after 14 d of storage. Inability of shrimp salad and coleslaw to support the growth of L. monocytogenes may be attributed to the acidic pH (4.8 and 4.5, respectively) of the formulations used in this study. Results show that the behavior of L. monocytogenes in potentially hazardous ready to eat foods is dependent upon the composition of individual food products as well as storage temperature.[PUBLICATION ABSTRACT]