Quantification of persistence of the food-borne pathogens Listeria monocytogenes and Salmonella enterica during manufacture of Italian fermented sausages

The objective was to evaluate the survival capability and quantify the persistence of the food-borne pathogens Listeria monocytogenes and Salmonella enterica in the Cacciatore, Felino and Milano type salami preparation. The batter of each sausage was inoculated with a five-strain cocktail of L. monocytogenes or S. enterica (ca. 104–105 CFU/g) and their progression was monitored at specific time intervals during preparation of the sausages. Four different batches were prepared at different times for each sausage/pathogen combination. Different models were used to fit the experimental data and to calculate the kinetic parameters. The best model was chosen based on statistical comparisons. S. enterica proved to be more sensitive susceptible to fermentation and ripening processes than L. monocytogenes. Both pathogens, however, survived relatively well as the result of the conditions (pH, aw and fermentation temperature) prevailing during fermentation and ripening of the sausages. Water activity proved to be a key factor in the survival of the microorganisms. The statistical analysis of quantitative data gathered from challenge tests is useful for the food business operators as it can provide practical information on the process parameters combinations that could lead to a better control of the pathogens.