South Holland, IL, United States
South Holland, IL, United States

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Fleischman G.J.,U.S. Food and Drug Administration | Badvela M.K.,Illinois Institute of Technology | Rehkopf A.,Illinois Institute of Technology | Stewart C.M.,Illinois Institute of Technology | Stewart C.M.,Silliker Inc.
Journal of Food Protection | Year: 2010

The thermal death time kinetics of Salmonella Enteritidis (SE) was measured in buffer, egg yolk, and albumen using thin layer plastic sleeves. The sleeves allowed for the loading and sampling of liquids of high or unusual viscosity, as in the case of yolk and albumen, and accepted relatively large volumes (2 to 3 ml) of fluid. The sleeves maintained the volume of the fluid in a thin layer and could be easily handled for heat exposure. The thin layer maintained one-dimensional heat transfer and minimized temperature gradients, thus preventing parts of the fluid from experiencing different heating rates. A representative strain of SE associated with an egg-based salmonellosis outbreak was used in this study. The D-and z-values of the chosen strain, H7037, were measured in buffer, yolk, and albumen. In buffer, SE had the following mean (±standard deviation) D-values: D55°C = 3.51 ± 0.30 min, D57°C=1.75 ± 0.13 min, and D60°C=0.25 ± 0.06 min. In yolk, D58°C=0.90 ± 0.05, D 60°C=0.26 ± 0.03, and D62°C=0.20 ± 0.02. In albumen, D55°C=1.26 ± 0.31, D56°C= 0.68 ± 0.10, and D57°C=0.44 ± 0.04. The z-values for SE calculated from these D-values were 4.29 ± 0.39°C in buffer, 6.12 ± 0.26°C in yolk, and 4.63 ± 1.14°C in albumen. The sleeves allowed one consistent approach to determining thermal death time kinetics regardless of viscosity.


Youart A.M.,CSIRO | Huang Y.,CSIRO | Stewart C.M.,CSIRO | Stewart C.M.,National Center for Food Safety and Technology | And 4 more authors.
Journal of Food Protection | Year: 2010

A mathematical model was developed to predict time to inactivation (TTI) by high pressure processing of Listeria monocytogenes in a broth system (pH 6.3) as a function of pressure (450 to 700 MPa), inoculum level (2 to 6 log CFU/ml), sodium chloride (1 or 2%), and sodium lactate (0 or 2.5%) from a 4uC initial temperature. Ten L. monocytogenes isolates from various sources, including processed meats, were evaluated for pressure resistance. The five most resistant strains were used as a cocktail to determine TTI and for model validation. Complete inactivation of L. monocytogenes in all treatments was demonstrated with an enrichment method. The TTI increased with increasing inoculum level and decreasing pressure magnitude, from 1.5 min at 700 MPa and 2 log CFU/ml, to 15 min at 450 MPa and 6 log CFU/ml. Neither NaCl nor sodium lactate significantly influenced TTI. The model was validated with ready-to-eat, uncured, Australian retail poultry products, and with product specially made at a U.S. Department of Agriculture, Food Safety and Inspection Service (FSIS)-inspected pilot plant in the United States. Data from the 210 individual product samples used for validation indicate that the model gives "fail-safe" predictions (58% with response as expected, 39% with no survivors where survivors expected, and only 3% with survivors where none were expected). This model can help manufacturers of refrigerated ready-to-eat meats establish effective processing criteria for the use of high pressure processing as a postlethality treatment for L. monocytogenes in accordance with FSIS regulations. Copyright © International Association for Food Protection.


Muldoon M.T.,SDIX | Allen A.-C.O.,SDIX | Gonzalez V.,SDIX | Sutzko M.,SDIX | And 4 more authors.
Journal of AOAC International | Year: 2012

The SDIX RapidChekTM Listeria F.A.S.T. test system was validated against the U.S. Department of Agriculture-Food Safety and Inspection Service (USDA-FSIS) cultural reference method for the detection of Listeria species on stainless steel, plastic, rubber, and painted concrete. The SDIX method uses a proprietary RapidChek Listeria enrichment media for a one-step, 24-40 h enrichment at 30°C, and detects Listeria on an immunochromatographic lateral flow device in 10 min. Different Listeria species were used to spike each of the environmental surfaces. Environmental surfaces were spiked at levels ranging from 50 to 400 cfu /surface (1 in.2 swabs for painted concrete, 4 in.2 for sponge). A total of 120 spiked samples were tested by the SDIX method at 24 and 40 h and the cultural reference method. Total confirmed positives were 49, 54, and 48 for the SDIX 24 h method, the SDIX 40 h method, and the USDA-FSIS cultural reference method, respectively. Nonspiked samples from all environmental surfaces were reported as negative for Listeria spp. by all methods. The overall Chi square was 0.017 (P = 0.104) and 0.611 (P = 0.566) after a 24 and 40 h enrichment, respectively, indicating that the test method was equivalent in performance to the reference method at both enrichment times. The SDIX method was evaluated for the detection of 50 Listeria and 35 non-Listeria bacterial strains. All 50 Listeria strains were detected by the method (100% sensitivity). Five out of 35 non-Listeria species gave light test signals when grown in nonselective broth culture and tested undiluted. However, when grown in the RapidChek Listeria F.A.S.T. proprietary media, only one bacterial strain (Staphylococcus aureus) was detected, giving a very low test signal (97% specificity). The method was shown to be robust toward several alterations in testing and storage conditions. © 2012 Publishing Technology.


Pediococcus acidilactici ATCC 8042 and Enterococcus faecium NRRL B-2354 were investigated as potential surrogates for Salmonella serovars using thermal death time kinetics in products such as dry pet foods. The D-values of P. acidilactici ATCC 8042, E. faecium NRRL B-2354, and a cocktail of seven Salmonella serovars associated with low-moisture products were determined in a preservative-free dry pet food product at moisture levels of 9.1, 17.9, and 27.0% and heated between 76.7 and 87.8°C. The D-values were calculated by least squares linear regression. The D-values of P. acidilactici ATCC 8042 were higher than those for the Salmonella serovar cocktail but lower than those for E. faecium NRRL 2354. At 9.1% moisture, D-values of 6.54, 11.51, and 11.66 min at 76.7°C, 2.66, 3.22, and 4.08 min at 82.2°C, and 1.07, 1.29, and 1.69 min at 87.8°C were calculated for Salmonella serovars, P. acidilactici ATCC 8042, and E. faecium NRRL B-2354, respectively. The data suggest that the thermal inactivation characteristics of P. acidilactici ATCC 8042 can be utilized as a surrogate to predict the response of Salmonella in dry pet food products that are thermally processed at <90°C. Copyright ©, International Association for Food Protection.


Bird P.,Q Laboratories Inc. | Fisher K.,Q Laboratories Inc. | Boyle M.,Q Laboratories Inc. | Huffman T.,Q Laboratories Inc. | And 38 more authors.
Journal of AOAC International | Year: 2014

The 3M™ Molecular Detection Assay (MDA) Salmonella utilizes isothermal amplification of nucleic acid sequences with high specificity, efficiency, rapidity and bioluminescence to detect amplification of Salmonella spp. in food, foodrelated, and environmental samples after enrichment. A method modification and matrix extension study of the previously approved AOAC Official MethodSM 2013.09 was conducted, and approval of the modification was received on March 20, 2014. Using an unpaired study design in a multilaboratory collaborative study, the 3M MDA Salmonella method was compared to the U.S. Department of Agriculture/ Food Safety and Inspection Service (USDA/FSIS) Microbiology Laboratory Guidebook (MLG) 4.05 (2011), Isolation and Identification of Salmonella from Meat, Poultry, Pasteurized Egg, and Catfish Products for raw ground beef and the U.S. Food and Drug Administration (FDA)/Bacteriological Analytical Manual (BAM) Chapter 5, Salmonella reference method for wet dog food following the current AOAC guidelines. A total of 20 laboratories participated. For the 3M MDA Salmonella method, raw ground beef was analyzed using 25 g test portions, and wet dog food was analyzed using 375 g test portions. For the reference methods, 25 g test portions of each matrix were analyzed. Each matrix was artificially contaminated with Salmonella at three inoculation levels: an uninoculated control level (0 CFU/test portion), a low inoculum level (0.2-2 CFU/test portion), and a high inoculum level (2-5 CFU/test portion). In this study, 1512 unpaired replicate samples were analyzed. Statistical analysis was conducted according to the probability of detection (POD). For the low-level raw ground beef test portions, the following dLPOD (difference between the LPODs of the reference and candidate method) values with 95% confidence intervals were obtained: -0.01 (-0.14, +0.12). For the low-level wet dog food test portions, the following dLPOD with 95% confidence intervals were obtained: -0.04 (-0.16, +0.09). No significant differences were observed in the number of positive samples detected by the 3M MDA Salmonella method versus either the USDA/FSIS-MLG or FDA/BAM methods.


Yang H.,Roka Bioscience | Kaplan S.,Roka Bioscience | Reshatoff M.,Roka Bioscience | Hu E.,Roka Bioscience | And 11 more authors.
Journal of AOAC International | Year: 2012

ference culture methods for nine select foods and three select surfaces. The Roka method used Half-Fraser Broth for enrichment at 35 ± 2°C for 24-28 h. Comparison of Roka's method to reference methods requires an unpaired approach. Each method had a total of 545 samples inoculated with a Listeria strain. Each food and surface was inoculated with a different strain of Listeria at two different levels per method. For the dairy products (Brie cheese, whole milk, and ice cream), our method was compared to AOAC Official MethodSM 993.12. For the ready-to-eat meats (deli chicken, cured ham, chicken salad, and hot dogs) and environmental surfaces (sealed concrete, stainless steel, and plastic), these samples were compared to the U.S. Department of Agriculture/Food Safety and Inspection Service-Microbiology Laboratory Guidebook (USDA/FSIS-MLG) method MLG 8.07. Cold-smoked salmon and romaine lettuce were compared to the U.S. Food and Drug Administration/Bacteriological Analytical Manual, Chapter 10 (FDA/BAM) method. Roka's method had 358 positives out of 545 total inoculated samples compared to 332 positive for the reference methods. Overall the probability of detection analysis of the results showed better or equivalent performance compared to the reference methods.


Kwong W.,Roka Bioscience | Livezey K.,Roka Bioscience | Reshatoff M.,Roka Bioscience | Vaughn S.,Roka Bioscience | And 18 more authors.
Journal of AOAC International | Year: 2013

The AtlasTM Salmonella detection assay was compared to the reference culture methods for 12 foods and three surfaces. Comparison of the Atlas method to the U.S. Food and Drug Administration Bacteriological Analytical Manual (FDA/BAM) and U.S. Department of Agriculture-Food Safety and Inspection Service/Microbiology Laboratory Guidebook (USDA-FSIS/MLG) reference methods required an unpaired approach. Each method had a total of 320 samples inoculated with an S. enterica strain. Each food and surface was inoculated with a different strain of S. enterica at two different levels/method. Meat and egg products were compared to the USDA-FSIS/MLG 4.05 method. All other foods were compared to the FDA/BAM-5 method. The Atlas method had 148 positives out of 320 total inoculated samples, compared to 119 positives for the reference methods. Overall, the probability of detection analysis of the results showed equivalent or better performance by the Atlas Salmonella detection method compared to the reference methods. The Atlas Salmonella detection assay detected all 100 inclusive organisms and none of the 30 exclusive organisms. The lot-to-lot and kit stability studies showed no statistical differences between lots or over the term of the shelflife. Instrument-to-instrument testing showed no statistical difference between instruments. Finally, the robustness study showed no difference when the sample volume added to the Atlas Salmonella detection assay varied by 10%, storage time was extended up to 5 days before analysis, or enrichment times were varied from 12 to 24 h.


Jagadeesan B.,Neogen Corporation | Curry S.,Neogen Corporation | Foti D.,Neogen Corporation | Peterson L.,Neogen Corporation | And 5 more authors.
Journal of AOAC International | Year: 2011

Reveal® Salmonella Enteritidis (SE) is a lateral flow-based immunodiagnostic assay used for rapid detection of Salmonella enterica serovar Enteritidis from pooled shell eggs and environmental samples. This assay uses highly specific antibodies to accurately detect S. Enteritidis. Studies were conducted to compare the performance of this test against reference procedures for detection of S. Enteritidis from both pooled shell eggs and environmental samples. Pooled shell eggs were inoculated with low levels of S. Enteritidis and were enriched according to the procedure prescribed by the U.S. Food and Drug Administration. Uninoculated samples were included in each trial. Reveal SE exhibited 100% sensitivity and 100% specificity in comparison to the reference method in all trials. An abbreviated 48 h/(no hold) enrichment procedure was also developed and validated for detection of S. Enteritidis from pooled shell egg samples. This shortened enrichment procedure can be used in conjunction with the Reveal SE test and offers a significant enrichment time savings of 96 h. Chi-square analysis revealed that there was no significant difference between the abbreviated Reveal method and the reference procedure for detection of S. Enteritidis from pooled shell egg samples. Out of 245 natural drag swabs screened internally, only three samples tested Reveal SE positive and were confirmed by the reference procedure, resulting in 100% sensitivity and 100% specificity. An external laboratory screened 147 poultry house environmental samples and obtained 35 Reveal SE confirmed positives for Reveal SE sensitivity of 100% and specificity of 90%. Inoculation trials with drag swabs resulted in 96% sensitivity and 100% specificity. Thus, these data demonstrate that Reveal SE is a highly sensitive and specific assay for the detection of S. Enteritidis from both pooled shell eggs and environmental samples. © 2012 Publishing Technology.

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