Reduction of foodborne micro-organisms on beef carcass tissue using acetic acid, sodium bicarbonate, and hydrogen peroxide spray washes

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, 3% hydrogen peroxide, 1% sodium bicarbonate, 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 treatment (80 psi, 15 s, 25°C). Control samples received no spray treatments. Following treatments, lean and adipose samples were immediately analyzed or held for 24 h at 5°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.