Validation of a 5-log₁₀ reduction of Listeria monocytogenes following simulated commercial processing of Lebanon bologna in a model system

Recently, numerous product recalls and one devastating outbreak that claimed 21 lives were attributed to Listeria monocytogenes in ready-to-eat meat products. Consequently, the Food Safety and Inspection Service published a federal register notice requiring manufacturers of ready-to-eat meat and poultry products to reassess their hazard analysis and critical control point plans for these products as specified in 9 CFR 417.4(a). Lebanon bologna is a moist, fermented ready-to-eat sausage. Because of undesirable quality changes, Lebanon bologna is often not processed above 48.9°C (120°F). Therefore, the present research was conducted to validate the destruction of L. monocytogenes in Lebanon bologna batter in a model system. During production, fermentation of Lebanon bologna to pH 4.7 alone significantly reduced L. monocytogenes by 2.3 log₁₀ CFU/g of the sausage mix (P < 0.01). Heating the fermented mix to 48.9°C in 10.5 h destroyed at least 7.0 log₁₀ CFU of L. monocytogenes per g of sausage mix. A combination of low pH (5.0 or lower) and high heating temperatures (≥43.3°C, 115°F) destroyed more than 5 log₁₀ CFU of L. monocytogenes per g of sausage mix during the processing of Lebanon bologna. In conclusion, an existing commercial process, which was validated for destruction of Escherichia coli O157:H7, was also effective for the destruction of more than 5 log₁₀ CFU of L. monocytogenes.