Equivalency of peroxyacetic acid to chlorine as a shell egg sanitizing rinse.

Authors: Jones, Deana; Garcia, Javier; Gast, Richard; WARD, GARRETT - Former ARS Employee

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/4/2021
Publication Date: 2/18/2021
Citation: Jones, D.R., Garcia, J.S., Gast, R.K., Ward, G.E. 2021. Equivalency of peroxyacetic acid to chlorine as a shell egg sanitizing rinse. Poultry Science. https://doi.org/10.1016/j.psj.2021.101069.
DOI: https://doi.org/10.1016/j.psj.2021.101069

Interpretive Summary: s conducted to assess the residual levels of target bacterial isolates on the egg shell surface after exposure to a range of peroxyacetic acid concentrations to determine antimicrobial equivalence to 100 and 200 ppm chlorine. Nest run brown eggs from a commercial USDA organic flock were collected weekly over a four week period, allowing for 3 replicates of each challenge isolate to be conducted. Eggs were washed according to USDA AMS grade shield requirements, no sanitizing spray was applied at the time of washing. After washing, eggs were stored at 4'C until initiation of experimental protocols. Eggs were allowed to equilibrate to room temperature overnight before inoculation procedures. The results of the current study show that when applied according to USDA AMS standards (spray application at or higher than wash water temperature), 50 – 100 ppm peroxyacetic acid, as well as deionized water, are equivalent to 100 – 200 ppm chlorine in reducing microbial levels on the egg shell. Peroxyacetic acid concentrations of 250 – 500 ppm are biologically and statistically similar in ability to reduce egg shell microbial populations and achieve a microbial reduction much greater than 100 – 200 ppm chlorine.

Technical Abstract: In the US, all shell eggs processed under the USDA Agricultural Marketing Service voluntary grading standards must receive a shell sanitizing rinse after leaving the washing process of 100 – 200 ppm chlorine or its equivalent. A study was conducted to determine the concentration of peroxyacetic acid (PAA) which would be equivalent to 100 – 200 ppm chlorine (Cl) under the required washing conditions for shell eggs. Three isolates of Salmonella spp. (Enteritidis, Braenderup, and Typhimurium), as well as Enterobacter cloacae were utilized as inocula. Sanitizing treatments were: negative control; deionized water; 100 and 200 ppm Cl; and 50 – 500 ppm PAA (7 concentrations). Considering all isolates tested, 100 and 200 ppm chlorine had 2.6 and 2.3 log cfu/ml remaining on shell surface; 50 and 100 ppm peracetic acid had 1.9 and 1.0 log cfu/ml remaining, respectively, compared to untreated control average of 3.8 log cfu/ml (P < 0.001). Salmonella Typhimurium was least resistant to shell sanitizer treatments. Peroxyacetic acid concentrations > 250 ppm did not produce significant reductions in microbial populations as PAA concentration increased. Culturing for the prevalence of viable and injured organisms, 400 – 500 ppm PAA resulted in fewer eggs (P < 0.0001) being positive for Salmonella spp. Enterobacter cloacae was culturable via enrichment from 99.4% of inoculated eggs, regardless of sanitizer treatment. The results of this study indicate that 50 -100 ppm PAA is equivalent to 100 – 200 ppm chlorine in reducing egg surface microorganisms. The use of 400 – 500 ppm PAA resulted in a lower incidence of viable, but not culturable, Salmonella spp. on the shell surface. Enterobacter cloacae resulted in almost 100% viable, but not culturable, organism recovery for all sanitizing treatments and should be considered as an indicator organism when studying processing facility sanitation procedures.