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

Abstract

Three separate studies were conducted to determine the effectiveness of various temperature water spray washes (Wt), wash and steam combinations (WtS), and vacuum and wash combinations (VWt) for reducing fecal bacteria on sheep and beef carcasses. Wt of 15.6, 54.4, and 82.2°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 CFU/cm2 were subjected to all wash combinations. W82.2 and W82.2S reduced 6 log CFU/cm2 bacterial populations as much as 4.0 log cycles. When carcasses were subjected to WtS and W82.2, the initial contamination levels (4 and 6 log CFU/cm2) had little effect on final bacterial levels (2.7 to 3.3 log CFU/cm2). However, uninoculated carcasses with initial bacterial populations of 2.5 log CFU/cm2 experienced a 1.5-log-cycle reduction when subjected to WtS and W82.2. 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°C), low pressure (20 psi) wash in combination with a high pressure (125 psi), warm water (30°C) wash (W72/30). Reductions on beef of 2.7, 3.3, and 3.4 log cycles for aerobic plate count (APC), coliforms, and E. coli populations, respectively, were observed. When a commercial steam-vacuum was used in conjunction with W72/30, reductions of 3.1, 4.2, and 4.3 log cycles for APC, coliforms, and E. coli populations, 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.