Russell Scott M, Fletcher Daniel L, Cox Nelson A
Department of Poultry Science, University of Georgia, Athens, Georgia 30602-2772.
USDA, Agricultural Research Service, Richard B. Russell Agricultural Research Center, Athens, Georgia 30613 USA.
J Food Prot. 1995 Oct;58(10):1124-1128. doi: 10.4315/0362-028X-58.10.1124.
Experiments were conducted to determine the ideal medium for detection of temperature abuse of fresh broiler chicken using impedance microbiological techniques. In three separate trials, 15 ready-to-cook broiler chicken carcasses were obtained from the chiller exit of three separate processing plants. Five carcasses were sampled immediately (day 0), 5 carcasses were sampled after temperature abusing at 25°C for 12 h and holding at 3°C for 6 days (temperature abused), and the remaining 5 carcasses were sampled after holding at 3°C for 7 days (day 7 controls). Whole-carcass rinses were diluted by placing 1 ml from each carcass into 9 ml of each of the following media: (1) brain heart infusion broth (BHI), (2) EC broth with 3% added dextrose (ECD), (3) CM medium with 2% added dextrose (CMD), (4) EC broth (EC), and (5) CM medium (CM). The diluted samples were assayed in duplicate at 43°C using impedance microbiological techniques. Once a detection time (DT) was recorded, one ml of the sample was immediately recovered from the module well, diluted to 10, 10, and 10, and spread plated onto plate count agar. Two colonies from each carcass on plates with the highest dilution were randomly selected and identified. Since both gram-positive and gram-negative genera of bacteria were isolated from BHI-cultured carcass rinses and were responsible for changing the impedance of the medium, DTs were variable. EC and ECD media were not suitable for conducting temperature-abuse determinations. Using CMD medium to select for the growth of gram-negative bacteria, specifically E. coli , temperature-abuse determinations were more accurate than using a general medium, such as BHI. CMD appears to be the most effective medium tested to conduct temperature abuse determinations using impedance microbiological techniques.
进行了多项实验，以确定使用阻抗微生物技术检测新鲜肉鸡温度滥用情况的理想培养基。在三项独立试验中，从三个不同加工厂的冷却器出口获取了15个即食肉鸡胴体。立即对5个胴体进行采样（第0天），对5个胴体在25°C下进行12小时温度滥用处理并在3°C下保存6天（温度滥用）后进行采样，其余5个胴体在3°C下保存7天（第7天对照）后进行采样。将每个胴体的1毫升全胴体冲洗液分别加入9毫升以下每种培养基中进行稀释：（1）脑心浸液肉汤（BHI），（2）添加3%葡萄糖的EC肉汤（ECD），（3）添加2%葡萄糖的CM培养基（CMD），（4）EC肉汤（EC），以及（5）CM培养基（CM）。使用阻抗微生物技术在43°C下对稀释后的样品进行重复测定。一旦记录到检测时间（DT），立即从模块孔中取出1毫升样品，稀释至10、10和10，并涂布在平板计数琼脂上。从最高稀释度平板上的每个胴体中随机选择两个菌落并进行鉴定。由于从BHI培养的胴体冲洗液中分离出了革兰氏阳性和革兰氏阴性细菌属，且它们导致了培养基阻抗的变化，因此检测时间是可变的。EC和ECD培养基不适合进行温度滥用测定。使用CMD培养基选择革兰氏阴性细菌，特别是大肠杆菌的生长，温度滥用测定比使用通用培养基（如BHI）更准确。CMD似乎是使用阻抗微生物技术进行温度滥用测定测试的最有效培养基。
