IAFP 2009 Program Book and Abstract Book - AB168

Purpose: This study evaluated the growth of inoculated L. monocytogenes on slices of three ham products from different manufacturers, each formulated with and without antimicrobials, during vacuum-packaged storage. Methods: Commercially manufactured ham products formulated with and without antimicrobials were obtained from company A (product X) and B (products Y and Z). Ham formulated with antimicrobials contained 1.5% potassium lactate plus 0.05% sodium diacetate (product X) or 1.44% sodium lactate plus 0.1% sodium diacetate (products Y and Z). Products were sliced (0.1 to 0.2 cm thick) and cut (5 × 5 cm), inoculated (1-2 log CFU/cm2) with a 10-strain composite of L. monocytogenes, vacuum-packaged (two slices/sample) and stored at 4, 7 or 12°C. Samples were periodically analyzed (two replications/three samples per treatment) for L. monocytogenes (PALCAM agar) and total microbial (Tryptic Soy Agar with 0.6% yeast extract) populations for up to 90 days, depending on the product type and temperature. Lag phase durations, growth rates and maximum growth levels of L. monocytogenes on each of the products were calculated by fitting the growth curves with the Baranyi model. Results: Lag phase durations of L. monocytogenes on all ham products formulated without antimicrobials and stored at all temperatures were 0 to 2.9 days. As expected, growth rates of the pathogen on these products were lower when samples were stored at 4°C (0.19-0.26 log CFU/cm2/day) than at 12°C (0.67 to 0.95 log CFU/cm2/day); however, in all cases, growth to maximum levels of 6.5 to 7.9 log CFU/cm2 were obtained on all products without antimicrobials. Inclusion of antimicrobials in ham formulations extended the lag phase of L. monocytogenes; lag times at 4°C were up to 29.2, 5.2 and 22.2 days on products X, Y and Z, respectively. Growth rates of the pathogen on all products with antimicrobials were 0.06-0.14 (4°C), 0.06 to 0.17 (7°C) and 0.17 to 0.38 (12°C) log CFU/cm2/day. Significance: These data may be valuable to risk assessors when developing or updating risk assessments of L. monocytogenes on Ready-to-Eat meat products. P3-54 Weibull Type Distribution of Resistances of Escherichia coli to Different Concentrations of Potassium Sorbate DSC and Sodium Benzoate ANGELICA SANTIESTEBAN-LOPEZ, Sandra Guerrero, Enrique Palou, Stella M. Alzamora and Aurelio Lopez-Malo Universidad de las Americas, Puebla, Chemical and Food Engineering, Cholula, South Introduction: Weibull distribution applied to survival data is an interesting and useful model to explain microbial behavior under inhibition or inactivation conditions. Purpose: The main objective of our research was to evaluate and model the survival of Escherichia coli ATCC 35218 in tripticase soy broth (TSB) formulated with several concentrations (1000, 2000, up to 7000 ppm) of potassium sorbate or sodium benzoate. Methods: TSB formulated with each antimicrobial type and concentration was inoculated with 108 UFC/ml E. coli from stationary phase. E. coli survivors were monitored by plating 10-fold dilutions in tripticase soy agar (TSA) each hour during the first 10 h and then every 4, 6 or 8 hours (depending on the antimicrobial concentration) up to 48 h. Inoculated plates were incubated at 35°C for 24 h and the survivors were counted. In order to quantify the microbial response in every studied condition, the Weibull type distribution of resistances model was applied. Model parameters were obtained using nonlinear regression. Results: In general, both antimicrobials were effective suppressing E. coli growth; increasing antimicrobial concentration reduced the time to reach an 8 log cycle reduction. Experimental curves were highly correlated to predicted data, obtaining significant determination coefficients. E. coli survival curves in media with lower antimicrobial agent concentrations showed downward concavity (n > 1), and with higher concentrations exhibited upward concavity (n < 1). The increase in antimicrobial concentration reveals differences in the distribution of resistances. In general, when potassium sorbate was added the distribution of resistances showed more marked right-skewed curves than the observed curves for sodium benzoate, indicating that the majority of the organisms were destroyed in a short time after their exposure to potassium sorbate. Significance: The Weibull type distribution model was useful to explain observed differences between antimicrobial agents. The use of potassium sorbate was in general more effective than sodium benzoate in activating E. coli. P3-55 Bactericidal Efficacy of Salicid (Low Concentration of Electrolyzed Water) on Different Foodborne Pathogens SYED M. RAHMAN, Jae-Ho Choi, Jai-Moung Kim, Ding Tian, Jung-Beom Kim, Uranchimeg Purev, Kang-Hyun Choi and Deog-Hwan Oh Kangwon National University, Food Science and Biotechnology, Chuncheon, Korea, South Introduction: Numerous sanitizers have been examined for their effectiveness in killing or removing pathogenic bacteria. Recently, electrolyzed water has become a notable antimicrobial agent for its effective bactericidal activity and lack of residual effect on food. This is the first study that has been done on Salicid as a new device, producing sanitizer solution containing a low concentration of hypochlorous acid (2~5 ppm) that can be used in the food industry. Purpose: This study was designed to evaluate the efficacy of physiological saline solution produced from salicid device for inactivation of different types of foodborne pathogens. Methods: The efficiency of salicid (pH 6.7, ORP 760 mv, residual chlorine 2 and 5ppm) for inactivation of pure cultures of different foodborne pathogens (Escherichia coli O157:H7 ATCC 43894, Listeria monocytogenes ATCC 19115, Staphylococcus aureus ATCC 12488 and Salmonella Typhimurium ATCC 14028) with six exposure times (30 s, 1 min, 3 min, 5 min, 7 min, 10 min) was determined. A dipping method (dipping temp. 22 ± 20°C) was followed for this study. Log reduction per test material, contact time and organism were recorded. Results: Compared to the untreated control a reduction of 2.30 to 6.08 log CFU/ml for different foodborne pathogens was seen as the result of treatment with salicid. The highest bactericidal effect was found with Staphylococcus aureus 168 — Abstract Book Poster

IAFP 2009 Program Book and Abstract Book

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