Predictive modeling of Listeria monocytogenes survival and growth under combined stresses in Brazilian dry-cured loin-based agar

AIMS: Ready-to-eat dry-cured meats are characterized by combined hurdles such as reduced water activity, elevated salt content, and variable temperatures. Listeria monocytogenes may survive or adapt under these conditions. This study aimed to evaluate the behavior of L. monocytogenes under combined water activity (aw), sodium chloride (NaCl), and temperature stresses using a dry-cured meat-based agar designed to simulate physicochemical conditions encountered on cured meat surfaces and during dry-curing and storage processing conditions. Socol, a traditional Brazilian dry-cured pork loin, was used as the reference product for the development of this model system. METHODS AND RESULTS: The influence of aw (0.806-0.974), NaCl concentration (1.97%-9.53% w/w), and temperature (0.9°C-31.1°C) on the growth and/or survival of L. monocytogenes was investigated over 12, 24, 48, and 72 h using a Central Composite Rotatable Design (CCRD). Survival after 72 h of incubation was also evaluated in simulated gastric fluid (SGF). The predictive models accurately described the effects of aw, NaCl, and temperature on bacterial behavior, showing excellent validation performance (R² ≥ 0.96; Af ≥ 1.14; Bf ≥ 1.14). Water activity was the dominant factor influencing pathogen behavior, with increased growth observed at aw > 0.92. Temperature had no significant inhibitory effect, indicating that L. monocytogenes can survive under refrigeration conditions. The bacterium was fully inactivated in SGF under all tested conditions. CONCLUSIONS: The results emphasize the importance of water activity control to limit L. monocytogenes survival and growth in ready-to-eat dry-cured meats.