Microbial decontamination of beef and sheep carcasses by steam, hot water spray washes, and a steam-vacuum sanitizer

Three seperate studies were conduted to determine the effectiveness of various temperature water sparay washes (W₁), wash and steam combinations (W₁S), and vacuum and wash combinations (VW₁) for reducing fecal bacteria on sheep and beef carcesses contaminated with faces, using a hand-held spray nozzle. log CFU/cm² were subjected to all wash combinations. W_82.2 and W_82.2S reduced 6 log CFU/cm² bacterial populations as much as 4.0 log cycles. When carcasses were subjected to W₁S and W_82.2, 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 bacteriol populations of 2.5 log CFU/cm² experienced a 1.5-log-cycle reduction when subjected to W₁S 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°C), low pressure (20 psi) wash in combination with a high pressure (125 psi), warm water (30°C) wash (W_72/30). 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 W_72/30, 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.