The spray application of two commercial decontaminating agents for reducing bacterial populations associated with fecal contamination on beef was examined in two separate experiments. Individual pieces of prerigor lean beef tissue were inoculated with fresh bovine feces and subjected to a 15-s spray wash (75 lb/in2, 20°C) with water or various concentrations of Carnatrol™, composed of copper sulfate pentahydrate, or Timsen™, 40% N-alkyldimethylbenzylammonium chloride in 60% stabilized urea, and stored under refrigerated (5°C) conditions. When Carnatrol™ was applied to beef tissue at 20, 40, and 80 ppm, bacterial populations were not statistically different (P ≥ 0.05) than water-treated populations at days 0, 1, and 2. When Carnatrol™ was applied to tissues at 160 ppm, bacterial populations were statistically different (P ≤ 0.05) from water-treated tissue on all of the days examined; however, reductions were not greater than 0.58, 0.42, and 0.35 log CFU/cm2 at days 0, 1, and 2, respectively. Remaining bacterial populations resulting from spray applications of Timsen™ to tissues at 200, 400, and 800 ppm were not statistically different than remaining bacterial populations of water-treated tissues at days 0, 1, 2, or 3. Reductions in bacterial populations associated with Timsen™ were no greater than 0.40 log CFU/cm2 on any of the days examined. This study demonstrates that under conditions used in this study, spray washes with either of the two commercially available decontaminating agents were no more effective than water washes for reducing bacterial populations associated with fecal contamination on beef tissue.
