Inhibition of Salmonella sp. Listeria monocytogenes and Staphylococcus aureus in cooked ham by combining antimicrobials, high hydrostatic pressure and refrigeration

Recontamination of ready-to-eat products such as cooked ham during post-processing may be the cause of outbreaks of food-borne disease. The effectiveness of the combination of high pressure processing (HPP) at 600 MPa with the natural antimicrobials nisin and potassium lactate has been evaluated in sliced cooked ham spiked with 4 Log CFU/g of Salmonella sp., Listeria monocytogenes and Staphylococcus aureus after 3-months of storage at 1 and 6 °C. In non-HPP sliced cooked ham, the addition of nisin plus lactate inhibited the growth of L. monocytogenes during the entire storage period while the refrigerated storage inhibited the growth of Salmonella sp. and S. aureus. The application of an HPP reduced the levels of Salmonella and L. monocytogenes to levels below 10 CFU/g. These levels continued until the end of storage at both 1 and 6 °C. HPP produced a reduction of less than 1 Log CFU/g to S. aureus. The combination of HPP, nisin and refrigeration at 6 °C was necessary to decrease the levels of S. aureus by 2.4 Log CFU/g after 3-months of storage.