Optimizing the effects of nisin and NaCl to thermal inactivate Listeria monocytogenes in ground beef with chipotle sauce during sous-vide processing

Authors: HERNANDEZ-MENDOZA, EZEQUIEL - Centro De Investigacion En Alimentaction Y Desarollo; PEÑA-RAMOS, ETNA - Centro De Investigacion En Alimentaction Y Desarollo; Juneja, Vijay; VALENZUELA-MELENDRES, MARTIN - Centro De Investigacion En Alimentaction Y Desarollo; SCHEUREN-ACEVEDO, MARIA - Centro De Investigacion En Alimentaction Y Desarollo; Osoria, Marangeli

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/27/2023
Publication Date: 3/30/2023
Citation: Hernandez-Mendoza, E., Peña-Ramos, E.A., Juneja, V.K., Valenzuela-Melendres, M., Scheuren-Acevedo, M.S., Osoria, M. 2023. Optimizing the effects of nisin and NaCl to thermal inactivate Listeria monocytogenes in ground beef with chipotle sauce during sous-vide processing. Journal of Food Protection. 86(5):100086. https://doi.org/10.1016/j.jfp.2023.100086.
DOI: https://doi.org/10.1016/j.jfp.2023.100086

Interpretive Summary: Undercooked meat and meat products, cooked-in-bag, are commonly implicated as transmission vehicles in food poisoning outbreaks associated with Listeria monocytogenes. This suggests the need to better define and quantify the heat treatment given to these foods to ensure safety against the pathogen. We determined that L. monocytogenes can be rendered more sensitive to the lethal effect of heat if beef is supplemented with 120 IU of nisin and 0.4 % of salt. The mathematical model developed can be used to predict the time required at any temperature to kill a certain number of the pathogen. Meat processors can use the model to design lethality treatments in order to achieve specific log reductions of L. monocytogenes in ready-to-eat beef products.

Technical Abstract: Safety of sous-vide processed meat entrees, such as meatballs with chipotle sauce, can be compromised as a result of the mild temperatures used, especially when salt levels are reduced during its preparation. Listeria monocytogenes is one of the main thermoresistant pathogens that can compromise the safety of ready-to-eat food. Due to its thermal stability, nisin can be a good alternative to ensure the thermal inactivation of L. monocytogenes. The objective of this study was to optimize the levels of nisin and salt addition to thermal inactivate L. monocytogenes in sous-vide processed ground beef marinated in chipotle sauce, and to generate a predictive model. A five-strain cocktail was prepared and inoculated in ground beef marinated in chipotle sauce (3:2) with added nisin and salt. Meat samples were sous-vide processed at different temperatures (55-65C) and varying levels of nisin (0-120 IU) and salt (0-2%) established by a central composite design. Depending on the levels of these factors, D-values ranged from 49.71 to 0.27 min. A predictive model (p less than 0.05) was obtained by linear regression, which demonstrated that the variation in D-values could be explained by the linear effects of the 3 factors, the interaction between nisin and temperature, and the quadratic effects of salt and temperature. It was also observed that nisin presented a bactericidal effect while salt presented a protective effect on the thermal inactivation of L. monocytogenes. Adding 120 IU of nisin and 0.4 % of salt to the meat product at 63C can help to ensure food safety by making L. monocytogenes cells more sensitive to the lethal effect of heat. The results of the present study will allow the meat industry to use different sous-vide pasteurizing temperatures and ensure food safety in this type of product by the addition of the proper nisin and salt levels to effectively inactivate L. monocytogenes in ground beef marinated in chipotle sauce.