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K. S. YOON, Department of Human Ecology, University of Maryland Eastern Shore, 2103 Trigg Hall, Backbone Road, Princess Anne, MD 21853 and T. P. Oscar, Microbial Food Safety Research Unit, USDA, Agricultural Research Service.

JUSTIFICATION: The presence and survival of Salmonella on/in chicken during refrigerated and frozen storage continues to be of public health concern. Numerous studies have shown the effectiveness of chemical washing in decontaminating chicken carcasses, but its application is limited to loosely attached Salmonella on chicken carcasses. Also, injury and survival of Salmonella on chemically washed poultry products during refrigerated and extended frozen storage have not been addressed.

OBJECTIVES: Our objective was to investigate washing effects of salt and various phosphate solutions on firmly attached Salmonella on sterile ground chicken breast patties, as well as on their subsequent injury and survival during refrigerated and frozen storage.

METHODS: Chicken patties inoculated with S. typhimurium were incubated for 20 hours at 20^ºC, then washed for 10 min at 4^ºC with 10% salt and various phosphate solutions, including trisodium phosphate, sodium tripolyphosphate and tetrapotassium pyrophosphate. The washed samples were stored in a refrigerator for 16 days, in a -20^ºC freezer for 10 months, and subjected to 3 freeze-thaw cycles. The numbers of uninjured and injured S. typhimurium on chicken patties were determined by plating on selective and nonselective media.

RESULTS: Washing the inoculated chicken with salt and various phosphate solutions before storage reduced S. typhimurium by 0.62-1.18 logs but did not significantly affect the number of injured S. typhimurium. The numbers of S. typhimurium were gradually decreased during storage period, but no significant injuries of S. typhimurium were found after refrigerated, frozen storage and freeze-thaw cycles, irrespective of treatment. However, both salt and all phosphate washing significantly lowered the surviving populations of S. typhimurium in refrigerated and frozen chicken.

SIGNIFICANCE: These results indicate that salt and phosphate washing can be recommended to reduce the initial contamination of S. typhimurium on poultry. But still careful handling and cooking methods are required in retail markets and in the consumer's kitchen to reduce the health risk involved with refrigerated and frozen chicken consumption.