Recovering Low Levels of Various Salmonella Serotypes from Deep-frozen Broiler Carcasses by Direct Enrichment

Two hundred and forty broiler carcass halves were each inoculated with either 14 or 180 cells of Salmonella typhimurium . Each carcass half was then placed in a plastic bag, blast-frozen (-40 C) for 6 h, and stored at -23 C. After 1, 7 and 30 days of frozen storage, 80 of these samples were removed and allowed to thaw; then each carcass-half was shaken in its bag with 150 ml of added sterile water. Lactose broth was used to preenrich 40 of these rinse-fluid samples and selenite cystine broth was used for direct enrichment of the remaining 40 samples. S. typhimurium was successfully recovered from all 240 samples. Other serotypes successfully recovered by direct enrichment on similarly frozen carcass-halves stored for 30 days were Salmonella california , Salmonella derby , Salmonella heidelberg , Salmonella montevideo , Salmonella newport and Salmonella senftenberg . These data suggest that a preenrichment medium such as lactose broth may not be necessary for detection of salmonella on frozen broiler carcasses.