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United States Department of Agriculture

Agricultural Research Service

Related Topics


Location: Poultry Processing and Swine Physiology Research

2011 Annual Report

1a.Objectives (from AD-416)
1) Develop and analyze poultry processing methods that utilize electrolyzed water and antimicrobial fatty acids as microbiocides to decrease microbial contamination during poultry processing. 2) Develop innovative processing operations and recommend modifications in existing processing operations to decrease water use in commercial poultry processing. 3) Evaluate the movement of microorganisms from broiler carcasses to processing water and equipment, specifically scalders, eviscerators and chillers.

1b.Approach (from AD-416)
Alternative antimicrobial treatments such as electrolyzed water, salts of fatty acids, peroxyacetic acid, blends of organic acids, chlorine dioxide, monochloramines, cetylpyridinium chloride and ozone will be evaluated for activity against poultry pathogens and spoilage bacteria. Optimum conditions for applying antimicrobials, including concentration and methods (spray or immersion), will be identified. Treatments with the greatest efficacy against poultry pathogens will be tested further during immersion chilling with reduced water volumes or air chilling. Carcass cross-contamination and procedures of preventing cross-contamination will be determined by focusing experiments on three of the processing areas where the transfer of bacteria is greatest (scalding, defeathering and equipment surfaces). Experiments will also evaluate product contact surfaces as a source of cross-contamination. Partitioning experiments will be performed to separate pathogens on the exterior of the bird from those interior. Cross-contamination will be minimized by using antimicrobial treatments tested in subsequent experiments. Research will be transferred to processing and regulatory personnel for implementation into Sanitation Standard Operating Procedures (SSOPs) and Hazard Analysis and Critical Control Point System (HACCP) plans.

3.Progress Report
Studies were conducted that demonstrated that naturally occurring fatty acids can kill bacteria associated with poultry processing and that a simple assay can be used to screen the antibacterial activity of these fatty acids. Another study examined the antibacterial activity of chelating agents and indicated that two common chelators can inhibit the growth of bacteria found on processed poultry. A spreadsheet simulation was developed which determined that carcass rinsates must contain at least 48 bacteria before there is a 95% probability that Salmonella will be recovered from paired rinsate samples. Additional studies indicated that whole carcass enrichment was more effective than neck skin sampling or whole-carcass-rinsing in recovering Salmonella from carcasses. Washing carcasses in solutions of antimicrobial fatty acids indicated that these solutions significantly reduced the population of Escherichia coli, Campylobacter spp., and total plate count bacteria recovered from the carcasses. Research was conducted that demonstrated that the efficacy of spray washing in reducing carcass contamination was influenced by the concentration of lauric acid-potassium hydroxide used to wash the carcasses and the amount of time carcasses were washed. Research conducted using spreadsheet formulas to calculate probabilities of isolating different Salmonella serotypes from agar media showed that as the number of different serotypes on the agar increases, more colonies must be picked to ensure that all serotypes were selected. Research conducted using phylogenetic analysis to characterize Salmonella Enteritidis isolates recovered from commercial poultry processing operations demonstrated that Salmonella isolates on processed poultry may originate from several sources in poultry production system. Research examining cross contamination of carcasses during processing operations showed that Salmonella and E. coli can survive scalding operations and that these bacteria can be recovered from scalder water, scalder foam, and broiler carcasses in commercial processing facilities. Several Salmonella isolates were recovered from samples taken from scald tank samples, and isolates were characterized using a novel testing procedure developed at the Russell Research Center. The importance of the volume of water used in chill tanks was examined by cooling carcasses in different volumes of water, and results indicated that there was no difference in the number of bacteria recovered from carcasses by doubling the volume of chill water in the tanks. A survey was conducted that examined the amount of fresh water, recycled water, and sanitizers used during commercial turkey processing operations in the United States. An innovative, blood-free medium for growing Campylobacter was developed. Analyses of commercial scald water and carcasses collected from a typical three tank scald system showed that the majority of the bacteria are removed in the first scald tank and that the multiple tank design reduced the likelihood of cross-contamination. Replaced by Bridging Project #6612-41420-016-00D.

1. Use of the agar diffusion assay to examine bactericidal activity of alkaline salts of fatty acid. Fatty acids (FA) were examined as novel, environmentally friendly sanitizers that can be used to reduce broiler carcass contamination. A study was conducted using the agar diffusion assay to evaluate inhibitory activity of caproic, caprylic, capric, lauric, and myristic acids towards bacteria associated with poultry processing. Results indicated that inhibition of bacterial growth was correlated with FA concentration. The efficacy of the FA in inhibiting bacterial growth was caproic< myristic< caprylic< capric=lauric acid. Capric and lauric acid inhibited the growth of all bacterial isolates. Findings from these experiments indicate that FA can kill bacteria associated with poultry processing and that the agar diffusion method can be used to quickly screen FA formulations for their ability to kill bacteria. Research will provide poultry processors with novel sanitizers to reduce microbial contamination during processing.

2. Use of the agar diffusion assay to examine bactericidal activity of chelating agents. Studies were conducted using the agar diffusion assay to examine the antibacterial activity of the chelators, ethylenediaminetetraacetic acid (EDTA) and ethylenediaminedisuccinic acid (EDDS). EDTA is a synthetic, non-biodegradable chelator; and EDDS is a natural, biodegradable chelator. Both chelators can bind minerals that produce water hardness thereby reducing water hardness and increasing the ability of soaps and detergents to remove dirt and debris during washing. Results from experiments indicated that EDTA inhibited growth of all 9 bacteria used in the study while EDDS inhibited the growth of 2 bacteria. The addition of these chelating agents to formulations of sanitizers may improve the ability of the sanitizers to wash away microorganisms on chicken carcasses and reduce contamination by killing microorganisms. Incorporating these chelators in sanitizers will reduce the number of bacteria on processed poultry.

3. Testing of duplicate rinse aliquots for presence of Salmonella. Testing broiler carcass rinses for the presence of Salmonella is often performed in duplicate to insure that the presence of the pathogen is detected. There may be large variation in the recovery of Salmonella between duplicate samples; however, spreadsheet simulation was developed to test the probability that paired aliquots of rinsates would both contain at least one Salmonella bacterium under ideal conditions. Results indicated that the original sample volume must contain 48 bacteria before there is a 95% probability of agreement between paired aliquots. These findings indicate that there may be substantial disagreement between paired aliquots where the original test samples contains low numbers of Salmonella bacteria. These findings may influence methods used by regulatory agencies to detect Salmonella on processed carcasses.

4. Prevalence of Salmonella on neck skin and carcasses after immersion chilling. The sampling procedure used to detect Salmonella on broiler carcasses may determine whether the pathogen is detected. The prevalence of Salmonella on enriched samples of neck skin, whole-carcass-rinsates, and whole carcass sample from the same broiler carcass was determined. Carcasses were chilled by immersions in ice water, with or without chlorine, for 40 min and then subjected to a whole-carcass-rinse. Neck skin, carcass rinsates, and whole carcasses were enriched by incubation at 37oC in buffered peptone water. Salmonella in samples were isolated and identified. Whole carcass sampling detected the highest level of Salmonella, followed by neck skin sampling, then carcass rinsate sampling. Findings indicate that the method used to recover Salmonella from broiler carcasses may determine the efficacy of the recovery of the pathogen. Results may impact methodology selected by regulatory agencies to determine the level of contamination of broiler carcasses by Salmonella.

5. Improved detection of Salmonella on processed broiler carcasses using whole carcass enrichment. Whole-carcass-rinsing and neck skin sampling are the most frequently used methods to recover Salmonella from processed broiler chicken carcasses; however, these methods do not always detect low levels of Salmonella contamination or firmly attached Salmonella. This study was conducted to determine if incubating whole carcasses in an enrichment medium would be more effective in detecting Salmonella on broiler carcasses than using whole-carcass-rinse samples or carcass neck skin samples. Carcasses of live broilers that were raised on litter contaminated with Salmonella then processed at the pilot plant poultry processing facility and commercially processed broiler carcasses were used. Findings indicated that whole carcass enrichment was more effective than neck skin sampling or whole-carcass-rinsing in detecting Salmonella contamination. Research may lead changes techniques currently used by regulatory agencies to detect Salmonella on whole carcasses.

6. Comparison of bacteria recovered from eggs from caged and cage-free hens. Although commercial laying hens are primarily housed in wire cages in the Unites States, these laying systems have recently received criticism from animal welfare and consumer groups. Therefore, many egg producers are currently transitioning from caged systems to cage-free housing. This study was conducted to compare the level of bacterial contamination of eggs collected from caged and cage-free laying operations. Eggs were collect from both types of laying operations and one set of eggs from each operation was washed in a commercially available egg-washing solution. The level of bacterial contamination of washed and unwashed eggs from caged and cage-free layers was determined. Findings indicated that washing eggs significantly reduced bacterial contamination and that there was no significant difference in the number of bacteria recovered from the egg from caged or cage-free operations. Findings may impact consumer perception of differences between eggs from caged and cage-free layers.

Review Publications
Hinton Jr, A., Ingram, K.D. 2010. Comparison of the antivacterial activity of chelating agents using the agar diffusion method. International Journal of Poultry Science. 9:1023-1026.

Cason Jr, J.A., Cox Jr, N.A., Buhr, R.J., Richardson, L.J. 2010. Comparison of the statistics of salmonella testing of chilled broiler chicken carcasses by whole carcass rinse and neck skin excision. Poultry Science. 89:2038-2040.

Hannah, J.F., Wilson, J.L., Cox Jr, N.A., Cason Jr, J.A., Bourassa, D.V., Richardson, L.J., Musgrove, M.T., Rigsby, L.L., Buhr, R.J. 2011. Comparison of shell bacteria from unwashed and washed table eggs harvested from caged laying hens and cage-free floor-housed laying hens. Poultry Science. 90(7):1586-1593.

Hinton Jr, A., Ingram, K.D. 2011. Use of agar diffusion assay to evaluate bactericidal activity of formulations of alkaline salts of fatty acids against bacteria associated with poultry processing. Journal of Food Safety. 31:357-364.

Mead, G.C., Lammerding, A., Cox Jr, N.A., Doyle, M.P., Humbert, F., Kulikovskiy, A., Panin, A., Nascimento, V., Wierup, M., Biggs, R., Buhr, R.J., Cahill, S., Cason Jr, J.A., Chalermchaikit, T., Filho, R., Forshell, L., Hidalgo, H., Hofacre, C., Hupkes, H., Landinez, M., Madsen, M., Mulder, R., Richardson, L.J., Shi, Z., Smith, D., Toyofuku, H., Tuominen, P., Uyttendaele, M., Zwietering, M. 2010. Scientific and technical factors affecting the setting of salmonella criteria for raw poultry: a global perspective. Journal of Food Protection. 73(8):1566-1590.

Last Modified: 4/16/2014
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