Organic acids as an alternative method to control Salmonella enterica serotype Choleraesuis and Listeria monocytogenes in pork jowl fat

Growth Effects as a Function of pH and Temperature of Salmonella enterica serovar Choleraesuis in In Vitro Tests and Chicken Meat: Prediction and Modeling

The present study aimed to predict and model the growth of Salmonella enterica serovar Choleraesuis as a function of pH and temperature in in vitro tests and raw chicken meat. To describe the growth, the data were adjusted by the Modified Gompertz primary model. After comparison, they presented R2 values > 0.9799 and an RMSE of 0.092 to 0.274. With the values of µmax obtained by the primary model, it was possible to evaluate the influence of temperature using the secondary Gamma model. Comparing the results obtained experimentally with those predicted by the ComBase tertiary model, it was possible to verify that the analyses carried out in the laboratory show that Salmonella did not multiply for a longer time. At pH 5, 6, and 7 at 12 °C, ComBase presented a λ of 43, 31, and 28 h, while the experimental λ was 109, 63, and 85 h, respectively. A correlation was observed between rising temperatures and pH, leading to an increase in μmax and a decrease in λ. However, no correlation was found concerning ymax.

Use of Organic Acids to Control Escherichia coli and Staphylococcus aureus Infection in Swine Jowl Fat

The objective of this work was to evaluate the mortality of Escherichia coli and Staphylococcus aureus inoculated in fresh swine jowls treated with different concentrations of organic acids (lactic, acetic, citric, and ascorbic) for 1, 5, and 10 min. Lactic and acetic acids showed minimum inhibitory concentrations (MICs) of 1.25 and 0.94 µL/mL against E. coli and S. aureus, respectively. Citric and ascorbic acids showed MICs of 3.75 and 7.5 µL/mL for both bacteria. In swine jowl fat, lactic acid provided mortality above 90% for both bacteria, at a concentration of 0.21% for E. coli with 5 and 10 min of exposure and 1.06% for S. aureus already with 1 min of exposure. Acetic acid showed mortality above 85% for E. coli, in the concentrations above 1.06% after 10 min, and 1.28% after 1 min of exposure. As for S. aureus, the high mortality was 73% with the maximum concentration and exposure time evaluated. Citric and ascorbic acids showed mortality of 90 and 70% for E. coli with 2.0%, respectively, and around 70% with 1.75 and 2.0% for both bacteria's. It was determined that lactic and acetic acids have good antimicrobial action against E. coli, but only lactic acid can be used at an industrial level for the microbiological control of in nature fat from swine jowls against S. aureus.

Surface carcass treatment with olive mill wastewater polyphenolic extract against Salmonella Enteritidis and Listeria monocytogenes: in vitro and in situ assessment

In recent years, there has been an increased interest in substances that could inhibit or reduce microbial growth in food products. Olive oil industry by-products, due to bioactive compounds with potential antimicrobial properties such as polyphenols, could be used in carcass treatment to enhance hygienic and quality traits. The assessment of the antimicrobial efficacy of bioactive molecules against pathogens should be determined with in vitro and in situ models since it is not possible to evaluate it directly on carcasses at the slaughterhouse. This study aimed to evaluate the effect of an olive mill wastewater polyphenolic extract against Salmonella Enteritidis and Listeria monocytogenes, simulating carcass surfaces using bovine dermis samples that were experimentally contaminated with the selected pathogens. The minimum inhibitory concentration and minimum bactericidal concentration were first determined for S. Enteritidis and L. monocytogenes. In situ, bactericidal activity assessment was performed using 20 cm2 derma samples contaminated with 5 Log CFU/20 cm2 of S. Enteritidis and L. monocytogenes in separate trials. Treatment with the polyphenolic extract was not effective for either microorganism. In order to establish the bacteriostatic activity of the polyphenolic extract, suspensions of about 2 Log CFU/20 cm2 of S. Enteritidis and L. monocytogenes were used. Polyphenolic extract treatment was not effective against Salmonella, while for Listeria it allowed microbial growth to delay (around 1 Log CFU/cm2 difference at 3, 7, and 14 days between treated and control groups). Further investigations are needed to evaluate the application of polyphenolic compounds on carcass surfaces and their effects on sensory traits.