Ready-to-eat (RTE) meat and poultry products manufactured with natural or organic methods are at greater risk for Listeria monocytogenes growth, if contaminated, than their conventional counterparts due to the required absence of preservatives and antimicrobials. Thus, the objective of this study was to investigate the use of commercially available natural antimicrobials and post-lethality interventions in the control of L. monocytogenes growth and recovery on a RTE ham product.

Antimicrobials evaluated were cranberry powder (90MX), vinegar (DV), and vinegar/lemon juice concentrate (LV1X). Post-lethality interventions studied were high hydrostatic pressure at 400 (HHP400) or 600 (HHP600) MPa, lauric arginate (LAE), octanoic acid (OA), and post-packaging thermal treatment (PPTT). Parameters evaluated through 98 days of storage at 4±1°C were residual nitrite concentrations, pH, aw, and viable L. monocytogenes on modified Oxford (MOX) media. On day 1, OA, 90MX, DV, and LV1X yielded lower residual nitrite concentrations than the control, whereas HHP400, HHP600, and LAE did not. LAE, HHP400, and OA reduced L. monocytogenes population compared to the control after 1 day of storage by 2.38, 2.21, and 1.73 log10 colony-forming units per gram, respectively. PPTT did not achieve a significant reduction in L. monocytogenes populations. L. monocytogenes recovered and grew in all post-lethality intervention treatments except HHP600. 90MX did not inhibit the growth of L. monocytogenes, while DV and LV1X did.

Results of this study demonstrate the bactericidal properties of HHP, OA, and LAE and the bacteriostatic potential of natural antimicrobial ingredients such as DV and LV1X against L. monocytogenes.

Lavieri Nicolas A., Sebranek Joseph G., Brehm-Stecher Byron F., Cordray Joseph C., Dickson James S., Horsch Ashley M., Jung Stephanie, Larson Elaine M., Manu David K., and Mendonça Aubrey F.

Foodborne Pathogens and Disease. June 2014, 11(6): 462-467.