Koohmaraie Mohammad, Bosilevac Joseph M, De La Zerda Michael, Motlagh Ali Mohseni, Samadpour Mansour
IEH Laboratories and Consulting Group, 15300 Bothell Way N.E., Lake Forest Park, Washington 98155, USA.
U.S. Department of Agriculture, Agricultural Research Service, Roman L. Hruska U.S. Meat Animal Research Center, Clay Center, Nebraska 68933-0166, USA.
J Food Prot. 2015 Feb;78(2):273-80. doi: 10.4315/0362-028X.JFP-14-369.
The contamination of raw ground beef by Escherichia coli O157:H7 is not only a public health issue but also an economic concern to meat processors. When E. coli O157:H7 is detected in a ground beef sample, the product lots made immediately before and after the lot represented by the positive sample are discarded or diverted to lethality treatment. However, there is little data to base decisions on how much product must be diverted. Therefore, five 2,000-lb (907-kg) combo bins of beef trimmings were processed into 10-lb (4.54-kg) chubs of raw ground beef, wherein the second combo of meat was contaminated with a green fluorescent protein (GFP)-expressing strain of E. coli. This was performed at two different commercial ground beef processing facilities, and at a third establishment where ground beef chubs from the second grinding establishment were mechanically split and repackaged into 3-lb (1.36-kg) loaves in trays. The GFP E. coli was tracked through the production of 10-lb (4.54-kg) chubs and the strain could not be detected after 26.5% more material (500 lb or 227 kg) and 87.8% more material (1,840 lb or 835 kg) followed the contaminated combo at each establishment, respectively. Three-pound (1.36-kg) loaves were no longer positive after just 8.6% more initially noncontaminated material (72 lb or 33 kg) was processed. The GFP strain could not be detected postprocessing in any residual meat or fat collected from the equipment used in the three trials. These results indicate that diversion to a safe end point (lethality or rendering) of the positive lot of ground beef, plus the lot before and lot after should remove contaminated ground beef, and as such provides support for the current industry practice. Further, the distribution and flow of E. coli on beef trimmings through various commercial equipment was different; thus, each establishment needs to consider this data when segregating lots of ground beef and establishing sampling protocols to monitor production.
大肠杆菌O157:H7对生牛肉末的污染不仅是一个公共卫生问题，也是肉类加工商关注的经济问题。当在牛肉末样本中检测到大肠杆菌O157:H7时，阳性样本所代表批次之前和之后立即生产的产品批次将被丢弃或送去进行致死处理。然而，几乎没有数据可用于确定必须转移多少产品。因此，将五个2000磅（907千克）的牛肉边角料组合箱加工成10磅（4.54千克）的生牛肉末块，其中第二组肉被表达绿色荧光蛋白（GFP）的大肠杆菌菌株污染。这在两个不同的商业牛肉末加工设施以及第三个场所进行，在第三个场所，将来自第二个研磨场所的牛肉末块进行机械分割并重新包装成3磅（1.36千克）的条装，放在托盘中。通过生产10磅（4.54千克）的牛肉末块来追踪表达GFP的大肠杆菌，在每个场所，分别在比受污染组合多26.5%的物料（500磅或227千克）和多87.8%的物料（1840磅或835千克）之后，该菌株无法被检测到。在仅加工了比最初未受污染物料多8.6%（72磅或33千克）之后，3磅（1.36千克）的条装就不再呈阳性。在从三项试验中使用的设备收集的任何残留肉或脂肪中，加工后均未检测到表达GFP的菌株。这些结果表明，将阳性批次的牛肉末以及其之前和之后的批次转移到安全终点（致死或提炼）应能去除受污染的牛肉末，因此为当前行业做法提供了支持。此外，大肠杆菌在牛肉边角料上通过各种商业设备的分布和流动情况不同；因此，每个场所在隔离牛肉末批次并制定监测生产的采样方案时都需要考虑这些数据。
