IAFP 2009 Program Book and Abstract Book - AB28

Results: Log reductions of L. monocytogenes were > 2-log CFU/package on all ham types except one. Reductions on hams that had received a liquid smoke drenching during processing and prior to LAE treatment at 22 ml were lower than those on all other types, at 1.49 ± 0.60 log CFU/package, but reductions on hams with a very similar formulation that had been processed with a hot oil surface browning prior to LAE treatment at 22 ml were 2.20 ± 0.12 log CFU/package. Within each ham type, log reductions were not significantly different (P > 0.05) between treatment volumes spanning a 4-ml range. Significance: This study demonstrated the efficacy of LAE against L. monocytogenes on several ham types, thereby validating LAE as a post-lethality treatment for inactivation of the pathogen. T2-02 Short Term Bacteriocidal Efficacy of Lauric Arginate toward Listeria monocytogenes Present on the Surface of Frankfurters PETER J. TAORMINA and Warren Dorsa John Morrell & Co., Cincinnati, OH, USA Introduction: Aqueous antimicrobials such as lauric arginate (LAE) have potential for controlling Listeria monocytogenes on Ready-to-Eat meats, but research is needed to better define optimal treatment conditions. Purpose: This work was designed to elucidate the optimal conditions of post-lethality LAE application to frankfurters destined for vacuum-packaging in order to achieve > 1-log reduction of L. monocytogenes. Methods: Frankfurters were inoculated with L. monocytogenes and placed in packages (8 in each package) prior to spray treating with between 2 and 4.5 ml of solutions of 5,000 or 8,000 ppm LAE, 5,000 ppm LAE plus liquid smoke flavor, or water (control). Inoculated and treated frankfurters were vacuum-sealed and stored at 4.4°C for 0, 2, 4 and 8 days before surfaces were analyzed for surviving L. monocytogenes by use of a rinse method and plating on modified Oxford medium. Results: Treatment with 2 ml of 5,000 ppm LAE reduced L. monocytogenes from 7.13 to 5.82 log CFU/package on day 0, and 3 ml reduced populations from 7.22 to 5.79 log CFU/package on day 0. Treatment with LAE plus smoke flavor did not result in significantly different (P 2-log reduction within 2 days, with no further declines evident at day 8. Significance: This study demonstrates the short-term efficacy of LAE against L. monocytogenes on vacuum-packaged frankfurters and may provide supporting data for post-lethality treatments of frankfurters and sausages for control of the pathogen. T2-03 In vitro Inhibition of Listeria monocytogenes Exposed to Octanoic Acid and Acidic Calcium Sulfate Alone DSC and in Combination ALEX L. BRANDT, Margaret D. Hardin, Alejandro Castillo, Kerri B. Harris, Jimmy T. Keeton and T. Matthew Taylor Texas A&M University, Dept. of Animal Science, College Station, TX, USA Introduction: There is growing consensus that inhibition of foodborne pathogens can be improved by using combinations of antimicrobials on Ready-to-Eat (RTE) meat surfaces. Pairing different antimicrobials and utilizing their individual activities may be able to enhance the inhibition of pathogen growth. Purpose: The purpose of the study was to evaluate the capability of Octa-Gone (Ecolab, St. Paul, MN; active agent: Octanoic Acid (OCT)) alone or in combination with Safe2O:RTE01 (Mionix, Round Rock, TX; active agent: Acidic Calcium Sulfate (ACS)) to inhibit the Gram-positive foodborne pathogen Listeria monocytogenes in vitro. Methods: Pathogen inhibition was determined via a checkerboard assay. Strains of the pathogen (Scott A, 310, National Animal Disease Center (NADC) 2783 and 2045) were incubated aerobically in tryptose phosphate broth adjusted to pH 5.0. The minimum inhibitory concentration (MIC) was defined as the lowest concentration of antimicrobial that resulted in < 0.05 change in optical density at 630 nm (OD630) after 24 h of incubation at 35°C. Following MIC determination, experimental strains were exposed to OCT and ACS in combination. Strains were exposed to MIC and sub-MIC levels of antimicrobials; inhibition was again defined as < 0.05 change in OD630 after 24 h of incubation. Fractional inhibitory concentration (FIC) index values were defined as the sum of the FIC of antimicrobial A and antimicrobial B. Antimicrobial FIC values were calculated as the MIC of antimicrobial A in combination (concentration of A that produced inhibition across all concentrations of antimicrobial B) divided by the MIC of antimicrobial A applied singly. Antimicrobial interactions were defined as synergistic, additive, or antagonistic when the FIC index was 2.0, respectively. Results: The MIC for OCT and ACS was 25.00 ppm active agent and 0.156% (v/v) for L. monocytogenes Scott A, 310, NADC 2783, and NADC 2045, respectively. FIC index values for the OCT + ACS combination were 1.5, 2.0, 1.0 and 1.5 for L. monocytogenes Scott A, 310, NADC 2783 and 2045, respectively. Significance: Results indicate that the combination of the acidifying antimicrobials Octanoic Acid and Acidic Calcium Sulfate produces an additive-type inhibition upon L. monocytogenes in vitro. Further research is required to investigate and characterize the interactions of these and other approved antimicrobials for the inhibition of microbial pathogens on the surfaces of RTE meat products. T2-04 The Effect of Gaseous Ozone on the Survival of Surface Attached Environmental Listeria monocytogenes DSC Serotype 1/2a REBECCA BROWN, Louise M. Fielding and Arthur Tatham UWIC, Cardiff School of Health Sciences, Cardiff, United Kingdom Introduction: Gaseous ozone has considerable potential for use as a terminal sanitizer in the food industry. Traditionally used antimicrobials and fumigants have led to antimicrobial resistance and potential adverse health effects. Ozone leaves no toxic residues and has GRAS status for food processing. Listeriosis is an increasing problem in the over-60 age group and Listeria monocytogenes can be found on a range of surfaces within food processing plants and can 28 — Abstract Book Technical

IAFP 2009 Program Book and Abstract Book

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