Salmonella enterica and Listeria monocytogenes Inactivation Dynamics During Low−Temperature Sous Vide Cooking of Beef Steaks

Sous vide cooking is increasingly adopted in both food service and domestic settings due to its ability to deliver precise temperature control and consistent quality. However, food safety remains a critical concern, particularly regarding the inactivation of S. enterica and L. monocytogenes. This study evaluated the thermal inactivation kinetics of a multiserotype cocktail of S. enterica and L. monocytogenes in beef steaks subjected to sous vide cooking at four temperatures: 62.5 °C, 60.0 °C, 57.5 °C, and 52.5 °C. Pathogen enumeration was conducted at 5, 8, 15, and 45-min intervals, respectively, using selective agar. A reparameterized Weibull model was fitted to the data and was used to estimate the time required for a 6.5 log₁₀ cfu/g reduction. S. enterica achieved this reduction in 13.90, 21.13, 28.47, and 86.74 min, while L. monocytogenes required significantly longer times of 24.12, 36.87, 74.54, and 347.45 min at 62.5 °C, 60.0 °C, 57.5 °C, and 52.5 °C, respectively. Contrary to expectations, L. monocytogenes exhibited greater thermal resistance than S. enterica under these conditions. These findings underscore the importance of considering both cooking temperature and duration to ensure microbiological safety in sous vide applications. Furthermore, this research highlights the need for a comprehensive risk assessment to evaluate whether L. monocytogenes should be considered as a lethality indicator organism during sous vide processing.