Purpose: This study evaluated the efficacy of approved antimicrobial sprays (4.5% lactic acid, Citrilow™, and Beefxide®) for reducing STEC surrogates on processed bob veal carcasses under commercial conditions, and determined their impact on carcass color.
Methods: Bob veal calves (< 3 weeks of age and < 150 lbs) were harvested using USDA approved practices and were inoculated with a 5-strain mixture of surrogate E. coli bacteria. Levels of surrogate E. coli were determined post-inoculation, post-final water wash, post-antimicrobial spray, post-24-h chill, and post-2nd antimicrobial spray. Carcass color was measured using a Hunter MiniScan at each sampling point. Three experimental replications were conducted, each using four bob veal calves. Statistical analysis was done using SAS 9.4 and was a repeated measurement analysis with the repeated measurements over treatments.
Results: Water washing alone decreased (P < 0.05) E. coli levels by 0.88 log CFU/cm2. There were no differences in the effectiveness of the three antimicrobial treatments. Antimicrobial sprays applied to pre-rigor carcasses provided an additional 0.5 log cycle reduction compared to water alone. Carcass E. coli counts declined further (~0.4 log cycles) during the 24-h chilling period (total reductions of ca. 1.8 log CFU/cm2). A second antimicrobial spray to chilled carcasses provided no additional reductions. Chilled carcass color values (L*, a* and b*) were similar (P > 0.05) among all antimicrobials applied and the water only control.
Significance: These findings validate three USDA-approved antimicrobial sprays at the hot carcass level, providing the veal industry with practical tools to reduce their STEC positive rates, and in return, reducing the public health risk associated with STEC contamination of veal products.