Organic matter (OM) accumulation is common in chill tanks used to decontaminate raw poultry parts during processing. Organic matter negatively affects the antimicrobial activity of chlorine-based compounds, but its effect on the antimicrobial effectiveness of peroxyacetic acid (PAA) on poultry meat has not been described. Therefore, this study evaluated the effect of OM on the efficacy of PAA solutions in simulated post-chill tanks to reduce Salmonella artificially inoculated onto chicken parts. Chicken thighs were inoculated with a five-strain cocktail of poultry-borne Salmonella enterica serovars at ca. 6 log10CFU/ml. Then, the thighs were immersed for 30 or 45 s in PAA solutions (500 or 1,000 ppm) with chicken slurry to simulate OM accumulation (0, 15 or 30 g/L). The thighs were rinsed with neutralizing buffered peptone water (100 ml) and rinsates were plated onto XLD agar. Experiments were performed in triplicate (3 thighs/treatment/replicate). Chemical oxygen demand (COD), total nitrogen (TN), and pH were measured as the water quality parameters of the PAA solutions before and after use. COD ranged from 2,905 mg/L in unused 500-ppm solutions without added OM to 6,290 mg/Lin used 1,000-ppm solutions with 30 g/L of OM. Initial TN was 42.5 ± 2.0 mg/L and 60.9 ± 8.3 mg/L for 15 and 30 g/L OM, which increased by 27 ± 17 mg/L after use. The pH of solutions ranged from 3.16 ± 0.14 to 3.42 ± 0.09 for the 1,000-ppm solutions and from 3.59 ± 0.06 to 3.96 ± 0.06 for the 500-ppm solutions. Mean Salmonella reductions were 0.9 ± 0.1 log10CFU/ml of rinsate for the 500-ppm PAA treatment and 1.1 ± 0.1 log10CFU/ml of rinsate for 1,000-ppm PAA treatment. Exposure time did not have a significant effect on the logarithmic reductions. There was no significant effect of OM concentration (p>0.05) on the reductions, indicating that the antimicrobial efficacy was not affected and that PAA solutions may continue to be reused as long as the PAA concentration is actively monitored.
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