Using Critical Parameters to Ensure Efficacy of Selected Harvest and Fabrication Intervention Strategies used to Control Escherichia coli O157:H7 and Salmonella
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The objective of this study was to identify critical parameters of application for selected harvest and fabrication intervention strategies used to control Escherichia coli O157:H7 and Salmonella. Paired, boneless, beef strip loin (n=120, IMPS 180) were selected at a commercial cow harvest facility, transported to the Food Microbiology Laboratory, Texas A&M University, and inoculated with nonpathogenic, rifampicin-resistant E. coli organisms (ATCC #1427, 1428, 1430) to simulate harvest floor contamination. The beef strip loins were inoculated hot (~30°C) and then subjected to one of three chemical treatments (L-lactic acid, peroxyacetic acid, and acidified sodium chlorite) including subset variations for concentration and pH. Lactic acid was applied warm (~53°C) and at room temperature (~25°C), whereas the peroxyacetic acid, and acidified sodium chlorite were applied at room temperature (~25°C). Lactic acid was applied at concentrations of 2.5% and 5% using different water sources (tap and distilled), and at a common pH of ~2.2 using different water sources (tap and distilled). Peroxyacetic acid was applied at concentrations of 210 ppm and 150 ppm, and acidified sodium chlorite was applied at concentrations of 500 ppm and 1200 ppm. Half of the strip loins received the chemical interventions prior to chilling or “hot” (~25°C), whereas the other half received the interventions after a chilling for ~24 h at ~2°C. When applied to hot strip loins, only the 2.5% and 5% lactic acid treatments resulted in a greater than 1 log reduction, but for chilled strip loins all treatments achieved greater than a 1 log reduction. When tap water was used to prepare the intervention, there was a difference between reductions for hot (0.68 CFU/cm2) and chilled (2.02 CFU/cm2) product, but there were no differences between hot and chilled for distilled water. Also, there were no differences in reductions between using tap and distilled water for hot products or for chilled products. The pH of the meat surface was lowest for the 5.0% lactic acid (3.07) and highest for the 150 ppm peroxyacetic acid (6.07). These data support the significance of conducting in-plant validation studies utilizing the specific parameters used in the plant.
Labus, Cody John (2013). Using Critical Parameters to Ensure Efficacy of Selected Harvest and Fabrication Intervention Strategies used to Control Escherichia coli O157:H7 and Salmonella. Master's thesis, Texas A&M University. Available electronically from