Antimicrobial activity of vinegar water in chilled chicken carcasses

Very small poultry producers in West Virginia are very interested in learning the antimicrobial activities of commercial vinegar water during post-harvest broiler processing. We aimed to 1) evaluate the efficacy of vinegar water against pathogens and surrogate bacteria during the chilling of broiler carcasses, and 2) evaluate the anti-bacterial efficacy of 0, 50, and 75% vinegar water against surrogate bacteria during chilling at the Mobile Poultry Processing Unit (MPPU) pilot plant facility. In Study I, fresh organic broiler carcasses were inoculated with Salmonella Typhimurium, Campylobacter jejuni, and Enterococcus faecium, followed by chilling in the refrigerated 0, 50%, and 75% vinegar water for 1 or 24 h. In Study II, the MPPU-processed fresh broiler carcasses were chilled for 24 h in 0, 50, and 75% vinegar, 5 ppm of chlorine, and 2.5% of lactic/citric acid blend solutions. The broiler carcasses were then processed with D/E neutralizing solution in a standard poultry sampling bag for 30 seconds, followed by spread-plating onto tryptic soy agar plus 200 ppm-nalidixic acid (TSA-NaL), Brucella, and Bile-esculin agars (BEA)-NaL for S. Typhimurium, C. jejuni, and E. faecium, respectively. TSA- and BEA-NaL were incubated at 35°C for 48 h, and the Brucella agars were incubated in a microaerophilic jar at 42°C for 48 h. Mixed model procedure in R-program (3 × 2 × 3 factorial design) was used for data analysis with a significance level of P=0.05. Results showed that chilling in 50 and 75% of vinegar water for 1 h reduced (P < 0.05) 0.76-1.85 and 1.46-2.00 log₁₀ CFU/mL of S. Typhimurium and C. jejuni, and when the chilling time was extended to 24 h, the reductions increased to 1.20-2.52 and 1.8-2.27 log₁₀ CFU/mL, respectively. E. faecium showed less reduction (0.2-0.7 log₁₀CFU/mL, P < 0.05) than S. Typhimurium. MPPU pilot study showed that chilling in 50 and 75% vinegar water for 24 h reduced (P < 0.05) E. faecium by 3.29-3.64 log₁₀CFU/mL. Results suggested that applying 50 or 75% of commercial vinegar water for chilling 24h is effective to control foodborne pathogens on broiler carcasses, and E. faecium is a promising Salmonella surrogate during post-harvest validation studies.