Submitted to: Food Microbiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/10/1997
Publication Date: N/A
Citation: Interpretive Summary: An experiment was designed to determine if combination antimicrobial washes were more effective than single antimicrobial washes. Fat and lean beef carcass tissues were experimentally inoculated with sterile feces containing Escherichia coli, Listeria innocua, or Salmonella wentworth. A carcass washer especially designed for research purposes was used to apply (80 psi, 15 sec, 70 deg F) water, 1% vinegar, 3% hydrogen peroxide, 1% baking soda, or a combination of the compounds. In addition to bacterial populations, samples were analyzed for visible color changes, hydrogen peroxide, and surface pH immediately after treatments and after 24 h of refrigerated storage. Of the treatments investigated, a combination of vinegar/hydrogen peroxide was found to be the most effective, resulting in reductions of >99.9% for E. coli, L. innocua and S. wentworth on either tissue type. Color analyses immediately following spray washing with hydrogen peroxide indicated some bleaching of the beef tissue, but after 24 h, refrigerated storage, this bleaching effect was not detectable. Similarly, residual hydrogen peroxide was detected immediately after spray washing, but not after 24 h, refrigerated storage. Vinegar- and vinegar/hydrogen peroxide-treated tissues exhibited lower surface pH values on both tissue types immediately after spray washing and after 24 h, refrigerated storage. Based on the results of this study, spray wash treatments consisting of the right combination of antimicrobials can be more effective than single applications for reducing undesirable bacteria on beef surfaces.
Technical Abstract: In an attempt to control beef carcass contamination, a search for effective carcass washing treatments has become a major focus in the area of microbiological meat safety. Spray wash treatments utilizing 1.0% acetic acid (AA), 3% hydrogen peroxide (HP), 1% sodium bicarbonate (SB), alone or in combination, were performed to evaluate their efficacy in reducing numbers of Escherichia coli, Listeria innocua and Salmonella wentworth. The fascia surface of lean and adipose tissue was inoculated with sterilized fecal slurry containing the designated bacteria to obtain 5 log10 CFU/cm**2. A pilot scale model carcass washer was used to apply the spray treatments (80 psi, 15 sec, 25 deg C). Control samples received no spray treatments. Following treatments, lean and adipose samples were immediately analyzed or held for 24 h at 5 deg C for analysis of the treatments, for residual bacterial populations, surface pH, color analysis, and residual hydrogen peroxide. The combination wash of acetic acid/3% hydrogen peroxide (AAHP) resulted in the greatest reductions of 3.97 and 3.69 log10 CFU/cm**2 for E. coli on lean or adipose tissue, respectively. Spray washes with AAHP reduced L. innocua by 3.05 log10 CFU/cm**2 on lean tissue and 3.52 log10 CFU/cm**2 on adipose tissue, while S. wentworth was reduced by 3.37 log10 CFU/cm**2 on lean and 3.69 log10 CFU/cm**2 on adipose tissue. A spray wash treatment consisting of the right combination of safe and acceptable solutions may be effective for improving the microbial safety of beef.