A Model for Determining Differential Growth at 18 and 42°C of Bacteria Removed from Broiler Chicken Carcasses

Broiler chicken carcasses were obtained from a commercial processing facility, rinsed with 100 ml of sterile brain heart infusion broth and the solutions held at 3, 4, 5, 6, or 9°C for 10 d. At 0, 7, and 10 d, total plate counts (TPC) and impedimetric measurements were conducted at incubation temperatures of 18 and 42°C. For plates incubated at 42°C, counts did not change after 7 d of storage when broiler carcass rinses were held at 3 and 4°C. When held at 5, 6, and 9°C, however, plate counts increased significantly. Impedimetric detection times did not change when rinses were held at 3, 4, and 5°C but decreased significantly for rinses stored at 6 or 9°C. Upon incubation at 18°C, TPCs increased and impedimetric detection times decreased significantly when carcass rinses were held at 3, 4, 5, 6, and 9°C. Mixed bacterial flora recovered from fresh broilers and incubated at 42°C do not grow in storage temperatures below 5°C as determined by TPC and 6°C as determined by impedance analysis. Such a model system may be applicable to practical food handling systems to determine if products were held above a given temperature.