| Restrictions on the use of conventional antimicrobials, combined with the restricted use of nitrite and nitrate, have generated concerns over the perceived risk for foodborne illness associated with natural and organic RTE meat and poultry products. Thus, the use of natural antimicrobial interventions alone and in combination with post-lethality interventions as a means to inhibit the recovery and growth of Listeria monocytogenes in naturally cured RTE processed meats was the focus of the work reported in this dissertation. Natural antimicrobials evaluated were cranberry powder, vinegar, and vinegar and lemon juice concentrate. Post-lethality interventions studied were high hydrostatic pressure, lauric arginate, octanoic acid, and post-packaging thermal treatment. Parameters evaluated through 98 days of storage at 4°C included viable L. monocytogenes on modified Oxford (MOX) and thin agar layer (TAL) media. The vinegar and vinegar and lemon juice concentrate ingredients exhibited strong bacteriostatic properties against L. monocytogenes whereas cranberry powder did not. However, none of these natural antimicrobial ingredients exhibited bactericidal properties under the conditions or these studies. Additionally, the high hydrostatic pressure, octanoic acid, and lauric arginate post-lethality interventions demonstrated significant bactericidal effects on initial numbers of L. monocytogenes whereas the post-packaging thermal treatment investigated did not. Nonetheless, although beneficial from the standpoint of initial lethality, none of these post-lethality interventions offered protection against the growth of surviving L. monocytogenes upon storage of the products and under the conditions of these studies. Furthermore, upon studying the combination of natural antimicrobial ingredients with the use of post-lethality interventions, results showed that implementing the high hydrostatic pressure, octanoic acid, or lauric arginate post-lethality interventions in combination with vinegar or vinegar and lemon juice concentrate, under the conditions of these studies, represent promising multiple-hurdle approaches for not only addressing the potential presence of L. monocytogenes in naturally cured RTE processed meat products, but also at inhibiting the potential recovery and growth of those cells that remain viable over the refrigerated storage of the products. The combinations of these hurdles represent effective options that could be instituted by manufacturers of organic and natural processed meat products in their L. monocytogenes control plans. |
