Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 12, 2004
Publication Date: December 1, 2004
Citation: Bhaduri, S., Cottrell, B.J. 2004. Survival of cold-stressed Campylobacter jejuni on ground chicken and chicken skin during frozen storage. Applied and Environmental Microbiology. V.70. pg 7103-7109. Interpretive Summary: Campylobacter is a significant cause of bacterial enteritis in humans in the United States. Foods of animal origin, primarily poultry products, are associated with Campylobacter infection. While Campylobacter is prevalent in chickens, relatively little is known concerning the ability of this organism to survive on poultry and poultry products when stored under refrigeration and freezing conditions. Therefore, the effects of refrigeration at 4 degrees C, freezing at -20 degrees C, and a combination of refrigeration and freezing on the survival of Campylobacter in ground chicken and chicken skin were examined. A significant portion of Campylobacter survived on both contaminated ground chicken and chicken skin samples during refrigerated and frozen storage. However, survival was less on chicken skin compared to ground chicken. Hence, Campylobacter has the opportunity to cause disease if refrigerated or frozen poultry products harboring this pathogen are not sufficiently cooked. Thus, freezing cannot replace sanitary production and handling of foods. This research furthers the understanding of the factors affecting the survival of Campylobacter exposed to cold stress.
Technical Abstract: Campylobacter jejuni is prevalent in chickens, however, relatively little is known concerning the ability of this organism to adapt to environmental conditions, such as cold stress, relevant to raw poultry and poultry products. Therefore, the effects of refrigeration at 4 degrees C, freezing at -20 degrees C, and a combination of refrigeration and freezing on the survival of C. jejuni in ground chicken and chicken skin were examined. Following the different treatments, samples were plated onto tryptic soy agar containing 5% sheep's blood and onto a selective agar (modified cefoperazone charcoal deoxycholate) to determine the survival of C. jejuni. Refrigerated storage alone for 3 and 7 days produced a decrease in cell counts that ranged from 0.31 to 0.81 log(10) CFU/g for ground chicken and chicken skin, respectively, using either plating medium. The decline in cell counts of C. jejuni after frozen storage with and without pre-refrigeration ranged from 1.38 to 3.39 log(10) CFU/g for chicken skin and from 0.56 to 1.57 log(10) CFU/g for ground chicken using the two plating media. The survival after freezing was significantly higher in ground chicken than in chicken skin either with or without pre-refrigeration. There was a greater decline in cell counts following freezing of chicken skin that had been refrigerated for 7 days when compared to those that had been refrigerated for 0, 1, or 3 days. This was not observed for ground chicken samples, possibly due to its composition. The recovery of C. jejuni was similar on both of the plating media following freezing. Although the decline in numbers of C. jejuni was greater on chicken skin compared to the ground chicken, a considerable portion of the organisms survived storage at 4 degrees C and -20 degrees C. Thus, storage under these conditions cannot ensure that poultry and poultry products contaminated with C. jejuni will not result in human illness.