Risk Assessment of Listeria monocytogenes in Ready-to-eat Meat from Plants to Consumption

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Virginia Tech

Listeriosis caused by Listeria monocytogenes (L. monocytogenes) has been of public concern since the 1980s. Among all the RTE food, deli meats are the major carrier for this pathogen. Eliminating or lowering the initial level of L. monocytogenes in RTE meat and poultry product in the plants is an important practice in reducing the risk of L. monocytogenes to the public due to the growth potential of L. monocytogenes in the RTE food product during storage. Research identifying the contamination at plants provided information for the Food Safety and Inspection Service (FSIS) to establish the Interim Final Rule, requiring the food processing plants that produce post-lethality exposed RTE meat and poultry product choose one of the three alternative plans to ensure good sanitation conditions during food processing or suppress the growth of L. monocytogenes during storage: post-processing treatment and use of growth inhibitor (Alternative1), post-processing alone (Alternative 2a) or use of growth inhibitor and sanitation program (Alternative 2b), and sanitation program alone (Alternative 3).

This research developed a comprehensive model that simulated the entire processes of RTE food production, taking into account potential transfer and growth of L. monocytogenes in RTE meat and poultry products. This plant-to-consumption model analyzed the effectiveness of the three alternative processes on reducing the L. monocytogenes in the RTE food products and also investigated the optimal sampling and sanitizing program. Results showed that formulation of food products with growth inhibitor has the greatest impact on reducing the risk of L. monocytogenes, followed by the post-processing treatment and sanitation intervention. Risk can also be reduced depending on alternatives. For example, 70% reduction if all are switched to alternative 2b and 91% reduction if all are switched to Alternative 1, compared with the current alternative selection by food establishments.

This study investigated several important factors in the sanitation program, analyzed the sensitivities of these factors, and proposed the reasonable improvement of the hold-and-test strategies by the plant-to-consumer mathematic model. Holding all the lots during the food contact surface (FCS) testing period instead of holding lots after finding the positive FCS would increase the detection rate of positive lots by three "times. These results may help the food establishments under Alternative 3 choosing the proper sampling and sanitation program or switching to Alternative 1 or 2.

Listeria monocytogenes, risk assessment, listeriosis, risk ranking, listeriosis, Ready-To-Eat food, deli meats, plant-to-consumption model