MODELING BACTERIAL SURVIVAL IN UNFAVORABLE ENVIRONMENTS

The long-term survival of pathogenic microorganisms was evaluated and modeled in simulated fermented and dried, uncooked sausages, such as salami and pepperoni. Listeria monocytogenes and Salmonella were inoculated in BHI broths with added lactic acid or lactate (0-1.5%), NaCl (0-19%) and NaNO2 (0-200 ppm) and then incubated at 4-42-degrees-C for up to 9 months. Enumerations of surviving cells showed several forms of declining curves, including classic first-order declines, shoulder or lag phases, and two-phase declines with shoulder. Two primary models were tested for their ability to depict the data. The effect of the environmental conditions on the parameters of the models were described with multiple regression equations (secondary models).