Quantitative exposure assessment of Listeria monocytogenes cross-contamination from raw to ready-to-eat meat under different food-handling scenarios

Cross-contamination of Listeria monocytogenes from raw to ready-to-eat (RTE) foods has caused a number of foodborne outbreaks. This study used the quantitative exposure assessment to analyze the transfer risk of L. monocytogenes from raw pork to RTE ham under different simulated food-handling scenarios (including different bacterial concentrations, cutting board materials, and cutting board cleaning methods). Results showed that, with the increase of temperature of cleaning water, the transfer rates from both pork to cutting board and cutting board to ham declined gradually, and cross-contamination could be avoided after the cutting boards in high concentration L. monocytogenes (HCLM) group were cleaned with tap water at 70 °C, and at 50 °C in the low concentration L. monocytogenes (LCLM) group. When the cutting boards were not cleaned, the contamination levels of L. monocytogenes transferred to ham through cross-contamination of wood, plastic, and stainless steel were 1.84 Lg (CFU/g), 1.76 Lg (CFU/g), 1.74 Lg (CFU/g), respectively in LCLM group, which were close to HCLM group (at 95% confidence level). These indicated that the potential risk of cross-contamination of meat contaminated with low concentrations of L. monocytogenes also needs to be elucidated. Overall, lower the initial contamination level of raw meat and the use of tap water of higher temperature to clean the cutting boards were observed to be effective in reducing the risk of cross contamination of L. monocytogenes in meat products.