Purpose: To determine the efficacy of 3.41% LA, 4.55% LA, and 3.87% Purac Spray 80 in reducing cocktail mixtures of 7 major serogroups of STEC considered adulterants by the USDA-FSIS and Salmonella.
Methods: Surface carcass samples were obtained from pre-rigor, freshly slaughtered cattle processed at a local slaughter facility. For each replication, n = 2 - 150 cm2 pieces were used for: no treatment, 3.41% LA, 4.55% LA, and 3.87% Purac Spray 80, all heated to 125°F. The study was completed in duplicate. Pieces were submersed in either a cocktail of STEC or Salmonella for 1 min, then placed onto racks for 30 min to allow for attachment. Untreated pieces were swabbed (50 cm2) to determine initial pathogen concentration. Immediately after attachment, the pieces were sprayed for 15 s in an industry equivalent CHAD spray cabinet. Treated samples were swabbed within 1 h of treatment to determine reductions on day 0. Pieces were stored at 0°C and separate areas were swabbed on days 1 and 2 to determine pathogen reductions. Swabs were stomached, serial dilutions were prepared and plated onto MacConkey or XLT4 agar, both with thin TSA overlay. Populations were converted to log CFU/cm2prior to statistical analysis.
Results: Each treatment significantly (P < 0.05) reduced the concentration of Salmonella by approximately 2.0 log CFU/cm2. STEC populations were significantly (P < 0.05) reduced by approximately 0.80 log CFU/cm2 by 4.55% LA and Purac Spray 80 and by 0.60 log CFU/cm2 by 3.41% LA. Significant reductions were noted for days 1 and 2 for both pathogens.
Significance: These data indicate that an intervention of lactic acid spray or Purac Spray does effectively reduce Salmonella and STECs on pre-rigor carcasses, thereby improving the safety of the product.