Yang Xianqin, Badoni Madhu, Tran Frances, Gill Colin O
Agriculture and Agri-Food Canada, 6000 C&E Trail, Lacombe, Alberta, Canada T4L 1W1.
J Food Prot. 2015 Feb;78(2):256-63. doi: 10.4315/0362-028X.JFP-14-226.
To investigate the microbiological effects of a hide-on carcass decontaminating treatment recently implemented at a beef packing plant, carcasses undergoing routine processing at the plant were sampled during successive periods in January/February, April/May, and September/October. During each period, samples were collected from carcasses before and after the decontamination of hide-on carcasses, after skinning, before decontamination of the skinned carcasses, and at the end of the carcass dressing process. At each stage of processing during each period, samples were obtained by swabbing an area of 1,000 cm(2) on each of 25 carcasses. Aerobes, coliforms, and Escherichia coli were enumerated. In most samples, coliforms were predominantly E. coli. In all three periods, the log mean numbers of aerobes and E. coli recovered from hides before decontamination were between 6.6 and 6.8 and between 5.3 and 5.9 log CFU/1,000 cm(2), respectively. The log mean numbers of aerobes recovered from decontaminated hides were 6.6 log CFU/1,000 cm(2) in January/February and April/May but 5.4 log CFU/1,000 cm(2) in September/October. The log total numbers of E. coli recovered from decontaminated hides in January/February and April/May were 2.4 and 3.8 log CFU/25,000 cm(2), respectively, but no E. coli was recovered from such carcasses in September/October. Log total numbers of aerobes and E. coli recovered from skinned or dressed carcasses were mostly >4 and between 1 and 2 log CFU/25,000 cm(2), respectively. Typing of 480 E. coli isolates by multiple-locus variable-number tandem repeat analysis (MLVA) identified 218 MLVA types. Most isolates recovered from carcasses in different periods or at different stages of processing were of different MLVA types. However, small numbers of MLVA types were recovered in more than one period or from both hides before and after decontamination and skinned or dressed carcasses. The findings show that the hide-decontaminating treatment disrupted the usual transfer of E. coli from hides to meat surfaces during carcass skinning.
为了调查一家牛肉加工厂最近实施的带皮胴体去污处理的微生物学效果，在1月/2月、4月/5月和9月/10月的连续时间段内，对该工厂进行常规加工的胴体进行了采样。在每个时间段内，从带皮胴体去污前后、剥皮后、去皮胴体去污前以及胴体修整过程结束时的胴体上采集样本。在每个时间段的每个加工阶段，通过在25头胴体的每头胴体上擦拭1000平方厘米的面积来获取样本。对需氧菌、大肠菌群和大肠杆菌进行计数。在大多数样本中，大肠菌群主要是大肠杆菌。在所有三个时间段中，去污前从牛皮上回收的需氧菌和大肠杆菌的对数平均数量分别在6.6至6.8以及5.3至5.9 log CFU/1000平方厘米之间。1月/2月和4月/5月从去污后的牛皮上回收的需氧菌对数平均数量为6.6 log CFU/1000平方厘米，但9月/10月为5.4 log CFU/1000平方厘米。1月/2月和4月/5月从去污后的牛皮上回收的大肠杆菌对数总数分别为2.4和3.8 log CFU/25000平方厘米，但9月/10月从这些胴体上未回收大肠杆菌。从去皮或修整后的胴体上回收的需氧菌和大肠杆菌对数总数大多分别>4和在1至2 log CFU/25000平方厘米之间。通过多位点可变数目串联重复分析（MLVA）对480株大肠杆菌分离株进行分型，鉴定出218种MLVA类型。在不同时间段或不同加工阶段从胴体上回收的大多数分离株属于不同的MLVA类型。然而，在不止一个时间段内或从去污前后的牛皮以及去皮或修整后的胴体上都回收了少量的MLVA类型。研究结果表明，牛皮去污处理破坏了胴体剥皮过程中大肠杆菌从牛皮到肉表面的通常转移。
