Elsevier

Food Control

Volume 27, Issue 2, October 2012, Pages 351-361
Food Control

Review
Do any spray or dip treatments, applied on broiler chicken carcasses or carcass parts, reduce Salmonella spp. prevalence and/or concentration during primary processing? A systematic review–meta-analysis

https://doi.org/10.1016/j.foodcont.2012.04.004Get rights and content

Abstract

Context

Broiler chicken carcass spray and dip treatments are just two of many different interventions investigated to address the need to reduce Salmonella prevalence and concentration on broiler chicken carcasses during processing. However the results of published research are inconsistent and sometimes contradictory creating a need to formally evaluate, synthesize and summarize available research to avoid recommending ineffective treatments and identify key knowledge gaps for future work.

Objective

Evaluate intervention research that measured the efficacy of various spray and dip treatments, applied on broiler chicken carcasses during primary processing, as Salmonella prevalence or concentration on broiler carcasses, using systematic review–meta-analysis (SR–MA).

Data sources

A comprehensive electronic search was implemented in six databases and verified through a manual search of topic-related reference lists, related reviews or book chapters, and through consultations with selected topic experts.

Study inclusion

Control and challenge trials, cohort and before-and-after intervention research published in English that investigated the efficacy of any spray or dip treatments, applied to broiler chicken carcasses or carcass parts during processing, on Salmonella prevalence or concentration measured at the same level under laboratory, pilot plant and commercial conditions.

Risk of bias assessment and data extraction

Relevant research was evaluated for methodological soundness and completeness of reporting. The main characteristics of each study included in the review were extracted.

Data analysis

Random-effects MA of trisodium phosphate and lactic acid dip treatments (n = 12 and n = 32 trials with prevalence outcomes, respectively) resulted in homogeneous (p-value = 0.469; I2 = 0.0% and p-value = 0.284; I2 = 11.4%, respectively) summary effect estimates (OR = 1.16; 95% CI: 0.59–2.26 and OR = 0.05; 95% CI: 0.03–0.10, respectively). Visual evaluation of MA forest plots indicated overall reduction trends for six spray treatments reporting concentration outcomes: trisodium phosphate (n = 48 trials), acidic electrolyzed oxidizing water (n = 2), cetylpyridinium chloride (n = 43), lactic acid (n = 24), sodium bisulfate (n = 11) and potable water (n = 36). Moderate to considerable heterogeneity (p-value  0.1 and I2 > 25%) was observed for these treatments. Methodological soundness of included studies was poor and a lack of studies conducted under commercial conditions was observed.

Conclusions

Existing research on the efficacy of broiler carcass dips or sprays on Salmonella prevalence or concentration is limited and heterogeneous, precluding the full benefits of robust meta-analyses. Larger randomized controlled trials conducted under commercial conditions are needed.

Introduction

Broiler carcass treatments with a spray or dip are disinfecting practices implemented during broiler chicken processing after de-feathering and evisceration and before or after carcass chilling (Stopforth et al., 2007). Disinfectants could be of physical (e.g. hot water or steam), chemical (e.g. chlorine or organic acids) or biological (e.g. bacteriophages or bacteriocins) nature (Hugas & Tsigarida, 2008; Loretz, Stephan, & Zweifel, 2010) with reported efficacy ranging from 0.7 to 2.5 log10 reductions in concentration depending on the disinfectant type and application conditions (Northcutt, Smith, Musgrove, Ingram, & Hinton, 2005; Wang, Li, Slavik, & Xiong, 1997). The added efficacy of chemical and biological disinfectants over water has been considerably debated for spray washing applications since it is believed that the physical action from the spray alone will result in a sufficient removal of Salmonella from carcasses (Northcutt et al., 2005; Wang et al., 1997).

Systematic review (SR)–meta-analysis (MA) methodology offers a structured and repeatable format for identifying and appraising intervention research, and synthesizing, when appropriate, results from multiple, sufficiently similar studies using a quantitative MA (Borenstein, Hedges, Higgins, & Rothstein, 2009). The summary effect estimates are more precise and informative for end users of ‘intervention efficacy’ information, particularly if generated from a reasonable numbers of studies (n > 20 studies) and in the absence of statistically significant heterogeneity and publication bias.

Our objective was to evaluate the efficacy of various broiler chicken carcass spray or dip treatments on Salmonella prevalence or concentration (measured at the carcass level) from slaughter to primary chilling using SR–MA methods.

Section snippets

Methods

This study emerged from a large scoping study that investigated global published intervention, risk factor and prevalence research on Salmonella in broiler chicken. The efficacy of various on-farm and processing interventions, identified and prioritized at the scoping stage (Farrar, 2009), was investigated through multiple, separate SR–MAs, reported elsewhere (Bucher et al., 2011). The review protocol was developed a priori and pre-tested at the scoping stage, prescribing replicable procedures

Study inclusion and their characteristics

From 81 potentially relevant studies, 14 spray and 16 dip studies were found eligible for MA. Most of the 81 studies (n = 26) were excluded due to insufficiently reported results and dissimilar treatments (n = 11) (Fig. 1). The descriptive characteristics of the eligible studies are presented in Table 1. Thirty-six studies were excluded at the BA/MA stage, primarily due to insufficient data to conduct MA (26 studies), non-replicable intervention protocols (three studies), or a lack of control group

Discussion

Meta-analysis of trials investigating TSP dip treatments found no significant difference in the odds of Salmonella contamination for TSP dipped samples compared to samples dipped in potable water or buffered peptone water. Five of the trials included in this MA reported increases in Salmonella contamination, four reported reductions in Salmonella contamination and three reported no difference in contamination frequency between treated and control samples. These varied results may be due to

Conclusions

Meta-analysis of trials investigating TSP dips found that the treatments had no effect on the odds of Salmonella contamination compared to buffered peptone water or water dips. Significant heterogeneity in trials investigating various spray treatments (TSP, AEO water, CPC, LA, NaBis and potable water) limits the interpretation of their summary estimates, however overall trends in the data suggest that these treatments may be effective at reducing the concentration of Salmonella in broiler

Acknowledgements

The authors would like to thank the Ontario Ministry of Agriculture Food and Rural Affairs, the Poultry Industry Council and the Public Health Agency of Canada for funding. We would also like to thank Dr. Bob Wills, Dr. Hart Bailey, Lars Plym Forshell, Geoff Mead and Sue Reynolds for their expert contributions, Ashley Farrar, Janet Harris, Kyle Burgers, Vi Nguyen, Nanky Rai, Dr. Lea Nogueira Borden, Heather Desjardins, Dr. Vahab Farzan, Dr. Sarah Parker, Dr. Juliana Ruzante, Dr. America Mederos

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