Quantitative Risk Assessment of Listeria monocytogenes in Prepackaged, Non-Vacuum Sealed, Refrigerated Ready-to-Eat Cooked Meat Products in Chengdu

Objective  To conduct a quantitative risk assessment of Listeria monocytogenes (LM) in prepackaged, non-vacuum sealed, short shelf-life, ready-to-eat meat products in Chengdu using the @Risk software.

Methods  Based on monitoring data of LM contamination in pre-packaged, non-vacuum sealed, refrigerated ready-to-eat meat products in Chengdu obtained from a previous study, a risk assessment model was established. The risk of LM infection caused by consuming cooked meat products in different groups of people was quantitatively assessed. In addition, the growth of LM in cooked meat products, from retail to consumption, was also taken into consideration in the assessment.

Results  In Chengdu, the numbers of potential cases of listeriosis caused by consumption of prepackaged, non-vacuum sealed, refrigerated ready-to-eat meat products were 0.01 (95% confidence interval CI: 0-1.71 × 10^－2) per year per million in healthy individuals aged 5- < 65 years old, 0.22 (95% CI: 0-2.67 × 10^－1) in healthy individuals aged 65 and above, and 2.88 (95% CI: 3.85 × 10^－8-4.35) in pregnant women. According to the results of the sensitivity analysis, the initial pollution level of LM in the retail stage was the most important factor affecting the prevalence (R = 0.25), followed by retail temperature (R = 0.08), retail time (R = 0.07), and amount of consumption per meal (R = 0.07).

Conclusions  For pre-packaged, non-vacuum sealed, cooked meat products, the most important measure to reduce the prevalence of listeriosis is to control the initial contamination level, which requires food processing plants to regularly clean and strictly disinfect the processing environment and equipment to minimize LM contamination at the source. Retail delicatessens should strictly maintain a storage temperature below 5.0 ℃ and strictly adhere to product shelf-life recommendations. As for consumers, they should consume these meat products as soon as possible after purchase or store them under refrigerated conditions and shorten the storage time. Pregnant women should thoroughly heat the meat products before eating to reduce the risk of listeriosis.