Comparison of Acidified Sodium Chlorite, Chlorine Dioxide, Peroxyacetic Acid and Tri-Sodium Phosphate Spray Washes for Decontamination of Chicken Carcasses

Abstract

The objective of this study was to directly compare the antimicrobial effect of acidified sodium chlorite (ASC), chlorine dioxide (CD), peroxyacetic acid (PAA) and tri-sodium phosphate (TSP) on naturally occurring Campylobacter, Enterobacteriaceae and Pseudomonas spp. on the breast and neck skin of chicken carcasses treated post-evisceration and prior to primary chilling. Naturally contaminated Campylobacter-positive chicken carcasses, obtained from a commercial processing line immediately post-evisceration but prior to the inside–outside wash, were treated in a purpose-built automated spray rig. Replicated batch treatments for 15 and 30 s of chemical and water-only spray wash were performed. Untreated control carcasses were examined to provide baseline data for the initial numbers. Numbers of colony-forming units (CFU) per gram of skin excised from neck and breast locations were determined using selective agar media. For analysis, the results were subdivided into six microbe type/skin location combinations with each subdivision ranked by the following: (a) CFU remaining after treatment, (b) mean reductions and (c) the proportional change in numbers of samples below the limit of detection (LoD). The three groups of bacteria responded similarly to the chemicals applied. Campylobacter spp. were no more susceptible than the other two groups. No single chemical treatment gave the best effect across all ranking methods. Generally, ASC and TSP were more effective in reducing microbial counts than PAA, with CD and water having the least effect. A 30-s chemical treatment was usually more effective than a 15-s treatment. Where only a short (15 s) spray time is possible, ASC appears to be the most effective of the chemicals tested. Where longer treatments are possible, TSP becomes the most effective choice.