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United States Department of Agriculture

Agricultural Research Service

Title: Microbial Decontamination of Beef and Sheep Carcasses by Steam, Hot Water Spray Washes, and a Steam-Vacuum Sanitizer

Authors
item Dorsa, Warren
item Cutter, Catherine
item Siragusa, Gregory
item Koohmaraie, Mohammad

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 30, 1995
Publication Date: N/A

Interpretive Summary: In order to lower the incidence of pathogenic bacteria such as E. coli O157:H7, the red meat industry is in need of decontamination procedures. A series of experiments was conducted to identify strategies for decontamination of beef carcasses. These studies demonstrated that hot water and steam application plus steam-vacuuming are effective, practical and efficient decontamination protocols to clean feces and associated bacteria from beef carcasses. The Kentmaster steam-vacuum system used in these studies utilizes a stainless steel vacuum head to remove contamination by delivering a continuous stream of 7-10 psi water at 190-200 deg F while simultaneously vacuuming the area around the stream of hot water. It was determined that a commercial carcass washer could be used to remove bacteria from beef carcasses with a hot water wash of low pressure (20 psi) used in combination with a high pressure (125 psi) warm water wash. However, regardless of how high the initial bacterial number was on carcasses, bacteria could only be removed to a certain level. In addition some carcasses had high levels of bacteria on them after the washes, indicating that spray washing with water alone is not an adequate way to decontaminate carcasses. The steam-vacuum system that employed the direct application of hot water with steam and vacuum, was able to satisfactorily decontaminate all carcasses of bacteria by as much as 99.999%. The use of the steam-vacuum system would reduce the amount of trimming needed on a carcass processing line as well as improve the microbial safety of beef carcasses.

Technical Abstract: Three separate studies were conducted to determine the effectiveness of various temperature water spray washes (W**t), wash/steam combinations (W**tS), and vacuum/wash combinations (VW**t) for reducing fecal bacteria from sheep and beef carcasses. W**t of 15.6, 54.4, and 82.2 deg C were administered to sheep carcasses contaminated with feces, using a hand held spray nozzle. Initial carcass bacterial populations of approximately 2.5, 4, and 6 log**10 CFU/cm**2 were subjected to all wash combinations. W**82.2 and W**82.2S reduced 6 log**10 CFU/cm**2 bacterial populations by as much as 4.0 log cycles. When carcasses were subjected to W**tS and W**82.2, the initial contamination levels (approximately 4 and 6 log cycles) had little effect on final bacterial levels (2.7-3.3 log cycles). However, uninoculated carcasses with initial bacterial populations of 2.5 log**10 CFU/cm**2 experienced a 1.5 log cycle reduction when subjected to W**tS and W**82.2. It is possible that hydration of a carcass before and during interventions affords some protection to bacteria. The next study used a commercial carcass washer to apply a hot water (72 deg C), low pressure (20 psi) wash in combination with a high pressure (125 psi), warm water (30 deg C) wash (W**72/30). Reductions on beef of 2.7, 3.3, and 3.4 log cycles APC, coliforms and E. coli, respectively, were observed. When a commercial steam-vacuum was used in conjunction with W**72/30, reductions of 3.1, 4.2, and 4.3 log cycles APC, coliforms and E. coli, respectively, were achieved. Implementation of these interventions could reduce the amount of trimming needed on carcass processing lines and would increase the microbial safety of beef carcasses.

Last Modified: 11/24/2014
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