Reduction of Campylobacter jejuni on poultry by low-temperature treatment

Campylobacter jejuni is a leading cause of acute bacterial gastroenteritis in the United States, with epidemiologic studies identifying poultry as a leading vehicle in human infection. Studies were conducted to determine rates of C. jejuni inactivation on poultry exposed to different cooling and freezing temperatures. A mixture of three strains of C. jejuni originally isolated from poultry was inoculated onto chicken wings at ca. 10(7) CFU/g. The results of the study revealed that the storage of wings at -20 and -30 degrees C for 72 h reduced the population of C. jejuni on wings by 1.3 and 1.8 log10 CFU/g, respectively. The results with regard to long-term freezing for 52 weeks revealed C. jejuni reductions of ca. 4 and 0.5 log10 CFU/g on wings held at -20 and -86 degrees C, respectively. Protocols were developed to superchill wings in Whirl-Pak bags with liquid nitrogen at -80, -120, -160, and -196 degrees C such that the internal portion of each wing quickly reached -3.3 degrees C but did not freeze. The results with regard to the superchilling of wings at different temperatures for 20 to 330 s (the time required for the wings to reach an internal temperature of -3.3 degrees C) revealed C. jejuni reductions of 0.5 log10 CFU/g for wings held at -80 degrees C, 0.8 log10 CFU/g for wings held at -120 degrees C, 0.6 log10 CFU/g for wings held at -160 degrees C, and 2.4 log10 CFU/g for wings held at -196 degrees C. The superchilling of wings to quickly cool meat to -3.3 degrees C (internal temperature) can substantially reduce C. jejuni populations at -196 degrees C when the wings are submerged in liquid nitrogen, but not at -80 to -160 degrees C when the wings are treated with vapor-state liquid nitrogen. The results of this study indicate that freezing conditions, including temperature and holding time, greatly influence the rate of inactivation of C. jejuni on poultry. The conditions used in the poultry industry to superchill poultry to a nonfrozen-state internal temperature are not likely to substantially reduce Campylobacter populations on fresh products.