IAFP 2009 Program Book and Abstract Book - AB66

Methods: Over 400 chicken carcasses were sampled using the FSIS bird rinse methodology. Carcasses exposed to levels between 360 and 1800 ppm PAA in a commercially available finishing chiller, and baseline carcasses chilled in totes without PAA were tested over a total of 4 days during 2 separate weeks to account for flock to flock variability. Due to the higher levels of PAA in the test, sodium thiosulfate was added to the rinsate in order to neutralize any residual prior to testing. Samples were tested using 3M™ Petrifilm™ for aerobic plate count, coliforms/E. coli, and for Salmonella using BAX® PCR (DuPont Qualicon; Wilmington, DE). Results: Aerobic plate counts were reduced from 3.41 to 5.19 log colony forming units (CFU) per mL of rinsate in the baseline samples to 2.3 log (360 ppm PAA), 1.01 log (500 ppm), 0.32 log (675 ppm), 0.35 log (900 ppm), 0.78 log CFU/mL (975 ppm) and below detection (1800 ppm). Likewise, Salmonella was reduced from up to 90% positive in the controls to 0% positive for all levels of PAA except 975 ppm, which was found to be 6% positive (84% reduction vs. control at this test level). No organoleptic changes were observed in the treated carcasses. Significance: Spectrum™ PAA at use concentrations between 360 and 1800 ppm provided significant reduction in microbial recovery and Salmonella positives. At 1800 ppm, it reduced the microbial recovery to below detection limits, with no observed organoleptic issues. Use of Spectrum™ at these concentrations in finishing chillers will enable poultry processors to produce microbially safer products and meet USDA Category 1 status for Salmonella. Furthermore, due to the extremely low microbial recovery at these levels, the product shelf life may potentially be increased. FMC Corporation currently seeks FDA approval for higher use rates of Spectrum™. P1-14 Inhibition of Growth of Escherichia coli O157:H7 and Salmonella in Ground Beef Using Modified Atmosphere DSC Packaging Systems MANUEL V. ALVARADO, Angela Laury, Chance Brooks, Alejandro Echeverry and Mindy Brashears Texas Tech University, Animal and Food Science, Lubbock, TX, USA Introduction: Ground beef is commonly linked to E. coli O157:H7 and Salmonella outbreaks in the USA. The use of MAP increases the quality and shelf life of meat products. However, MAP products can still be temperature abused within the cold chain, allowing pathogen growth and increasing consumer risk. Purpose: The objective of this study was to determine if E. coli O157:H7 and Salmonella can be inhibited under consumer temperature abuse in MAP packaging environments compared to traditional PVC overwrap over a 24-day shelf life. Methods: Multiple strains of E. coli O157:H7 or Salmonella was used to inoculate (1 × 103 CFU/g) ground beef patties (four replications). The packaging treatments were: overwrap, vacuum, high-oxygen (HO)(80%O2/20% CO2), low-oxygen (CO), CO blend (0.4% CO/35% CO2/64.6% N2) , and low-oxygen (WOCO) blend (35%CO2/65% N2). Packages were stored at 37°F in the dark until processing. On day 6, packages were randomly placed in three temperature conditions (37°F -control), 8 h at 70°F, and 95°F for 4 h. After temperature abuse, packages were placed in a 37°F until sampling on days 6, 9, 11, 14, 24. Salmonella samples were plated onto Rambach agar and E. coli O157:H7 on MacConkey agar. The data was analyzed using descriptive analysis in SAS. Results: There were no significant interactions. E. coli O157:H7 was lower in ground beef packaged WOCO and CO than the other three packaging types regardless of sampling day or temperature abuse (P 0.05) in beef patties treated with Salmonella. Significance: This study indicates that the use of MAP may be inhibitory to E. coli O157:H7 during temperature abuse, therefore having a positive food safety impact in ground beef. P1-15 Heat and Acid Resistance of Escherichia coli Biotype I Used as Surrogates for Escherichia coli O157:H7 and Salmonella in the Validation of Pathogen Interventions in Beef Carcasses LUZ EDUVIGES GARAY-MARTÍNEZ, Alma A. Valenzuela-Morones, Marcela Okhuysen-Valle, Alejandro Castillo and Nanci E. Martínez-Gonzáles Universidad de Guadalajara, Laboratorio de Microbiología e Inocuidad de Alimentos. Farmacobiología, Guadalajara, South Introduction: Non-pathogenic bacteria isolated from environments that are common to E. coli O157:H7 and Salmonella may be used as surrogates for these pathogens in validating and verifying the effectiveness of intervention strategies designed to control hazards within a HACCP plan for beef carcasses, provided that these surrogates show a response to the factors involved in these strategies similar to that of the pathogens. Purpose: To compare the resistance to heat and acid of various isolates of E. coli biotype I obtained from beef carcasses, E. coli O157:H7 and Salmonella spp. Methods: Each of 26 isolates of E. coli biotype I, 7 of E. coli O157: H7 and 11 of Salmonella in stationary phase (12 h) in TSB was suspended in 10 mL of Butterfield buffer solution (pH 7.0) and heated at 55°C for 20 min and at 65°C for 10 min to determine heat resistance, and exposed to L-lactic acid solutions at pH 2.0, 3.0 and 4.0 to determine acid resistance at 35°C. At intervals during each treatment, samples were separated and tested for counts of these microorganisms by surface spreading on Tryptic Soy Agar (TSA) and TSA 4% NaCl. Results: The D-values for E. coli biotype I at 55°C and 65°C ranged from 8.5 to 40.8 min and 1.9 to 3.4 min, respectively. D-values for E. coli O157:H7 and Salmonella spp. ranged from between 7.2 to 24.5 min and 1.8 to 3.4 min and between 4.3 to 10.5 min and 1.7 to 2.7 min, respectively. The reduction of E. coli biotype I, E. coli O157:H7 and Salmonella was increased at 65°C. Mean log reductions at pH 2.0, 3.0 and 4.0 were 5.4, 2.6 and 0.5 log CFU/ml for E. coli biotype I; 5.8, 2.5 and 0.6 log CFU/ml for E. coli O157:H7; and 5.5, 3.5, 1.3 log CFU/ml for Salmonella respectively. Significance: Resistance to heat and acid of the E. coli biotype I isolates was higher or equal to that of E. coli O157:H7 and Salmonella. Therefore, E. coli biotype I may be a good index of these pathogens in validating and verifying methods for beef carcass decontamination. Poster 66 — Abstract Book

IAFP 2009 Program Book and Abstract Book

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