Listeria monocytogenes is a ubiquitous bacterium commonly found on raw meat and poultry products and has been associated with a number of foodborne illness outbreaks and food product recalls. This organism possesses a relatively high resistance to heat and can grow at refrigeration temperatures as low as 2°C and under low oxygen tension, such as that found in vacuum-packaged ready-to-eat (RTE) products. L. monocytogenes is given a zero-tolerance status in RTE meat and poultry products because of the high mortality rate associated with listeriosis. Although the cooking processes currently applied by the meat industry generally meet USDA Food Safety and Inspection Service (FSIS) requirements, the processing steps after cooking such as peeling, sorting, loading, slicing, packaging, and so forth, are potential sources of recontamination. An FSIS survey published in 2001 showed that 1% to 10% of retail RTE products were contaminated with L. monocytogenes. L. monocytogenes is currently the most concerned pathogen of post-cook contaminants among RTE meat and poultry products.
The CDC estimates the annual cost of illness due to Escherichia coli O157:H7 infections acquired from food or other sources as $405 million. Because of the high cost of illness due to E. coli O157:H7 infections, the federal government has implemented mandatory hazard analysis and critical control point (HACCP) programs and improved pre- and post-harvest processes to lower the contamination levels of meat products with this pathogen in meat and poultry plants and the juice industry. Most outbreaks of E. coli O157:H7 have been the associated with foods of bovine origin. In cases involving non-bovine foods, cross-contamination by beef or contamination with bovine feces during processing has often been suspected. It is believed that E. coli O157:H7 contamination of foods occurs from the intestinal tract of healthy cattle during slaughter and processing. Cross-contamination in abattoirs and other food processing plants have been reported to be responsible for several outbreaks of E. coli O157:H7. E. coli O157:H7 is known to produce extracellular polymeric substances (EPS) and form biofilms on food processing surfaces. Microorganisms are known to be more resistant to removal from foods and food contact surfaces in processing plants and to inactivation by sanitizers when contained in a biofilm than when dispersed in a liquid medium.
The stated objectives for this work were:
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