Variations on standard broiler processing in an effort to reduce Campylobacter numbers on postpick carcasses 1

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1 2011 Poultry Science Association, Inc. Variations on standard broiler processing in an effort to reduce Campylobacter numbers on postpick carcasses 1 M. E. Berrang,* 2 D. P. Smith, and R. J. Meinersmann * * USDA-Agricultural Research Service, Russell Research Center, 950 College Station Rd., Athens GA, 30605; and North Carolina State University, Department of Poultry Science, Raleigh Primary Audience: Processors, Quality Assurance Personnel, Researchers DESCRIPTION OF PROBLEM Campylobacter is a human pathogen that is often associated with live broilers [1 3] and their carcasses [4, 5]. Such contamination contributes to the epidemiological linkage of human SUMMARY Campylobacter numbers increase on broiler carcasses during defeathering because of leakage of gut contents through the vent. We tested several processing modifications designed to interfere with the transfer of Campylobacter from gut contents to the carcass surface. The numbers of Campylobacter detected on the breast skin of carcasses treated with each modification was compared with the numbers on control broilers processed using a standard method. Filling the vent and colon with commercially available canned spray foam did not consistently form an effective plug, and Campylobacter numbers increased during picking. Likewise, hanging carcasses with the vent pointed downward during defeathering was not effective in preventing the increase in Campylobacter numbers. Eviscerating carcasses by hand immediately before defeathering eliminated the increase in Campylobacter during automated feather picking. However, inadvertent contamination during hand evisceration led to higher numbers before feather removal. Therefore, we tested hand evisceration before scalding, allowing the scald water to kill and wash away Campylobacter spilled on the carcass during evisceration. Prescald evisceration was effective in significantly moderating the increase in Campylobacter on broiler carcasses during automated defeathering. Changing the order of standard broiler processing may help to control contamination with Campylobacter. Key words: broiler processing, Campylobacter, defeathering, feather picking 2011 J. Appl. Poult. Res. 20 : doi: /japr foodborne campylobacteriosis to poultry meat [6, 7]. Broiler processing is very effective in lessening the numbers of Campylobacter on carcasses; postchill carcasses have far lower numbers than prescald carcasses [8]. However, one of the ear- 1 Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the USDA. 2 Corresponding author: mark.berrang@ars.usda.gov

2 198 JAPR: Research Report ly steps in broiler processing, feather removal, results in a substantial increase in the numbers of Campylobacter on carcasses [8], thereby making it more difficult to produce a Campylobacter-free product. In earlier studies, we demonstrated that the increase in Campylobacter numbers during feather picking is due to the escape of contaminated gut contents from the vent of Campylobacter-positive carcasses [9]. The pressing action of picker fingers on broiler carcasses tends to force colon contents out of the vent. Colon contents may include more than a million cells of Campylobacter per gram [10], and even a very small amount can result in a significant increase in numbers on the carcass [11]. Airborne and surface-to-carcass contamination have been shown to be less important in the transfer of Campylobacter during automated feather removal [12, 13]. To interrupt the increase in Campylobacter on carcass surfaces during feather removal, several approaches could be used. Research has been conducted to address the increased Campylobacter contamination during feather removal. Plugging the vent [14], killing Campylobacter in the gut before it can come out and contaminate the carcass [15], skinning rather than traditional feather picking [16], and killing and washing Campylobacter off edible carcass surfaces have all been studied [17]. Another alternative may be to process carcasses in a different order or position to attempt to minimize the likelihood of Campylobacter contamination during automated feather picking. The objective of this study was to test the effect of several processing modifications on the numbers of Campylobacter recovered from the breast skin of postpick broiler carcasses. MATERIALS AND METHODS Standard Broiler Processing The broilers used in this study were obtained from a commercial broiler processor. At 42 to 56 d of age, broilers were subjected to a feed withdrawal period of approximately 12 h before processing. Broilers were then caged in plastic coops, transported to a pilot processing facility, and hung in groups of 10 in commercial-style shackles. In each set of experiments, control (standard processing) broilers were processed first. All broilers were stunned electrically with 12 V of direct current [18] and killed by cutting the blood vessels in the neck with an automated killing machine [19]. Carcasses were scalded at 56 C in a set of 3 triple-pass scald tanks [20]. Shackle speed was set so that carcasses spent 30 s in each scald tank. Carcasses then proceeded into a commercial defeathering machine [21] operated with a tap water spray (average total chlorine of 0.5 ppm). Processing Variations Experiment 1 Prepick Evisceration. Broilers were hung on shackles and allowed to proceed along the line as in standard processing. After all 10 broilers exited the scald tank, the line was stopped. Each broiler carcass was eviscerated by hand. First, using a knife, a small incision was made around the vent and a slit of approximately 3 cm was made in the skin of the abdomen. A gloved hand was used to enter the body cavity, grasp the gizzard, and pull the viscera out through the opening around the vent. After viscera were removed, each carcass was rinsed with a hose and cold tap water. Carcasses were then sampled as described below and allowed to progress through the automated feather picker. Vent Plug. Broilers were hung and allowed to proceed along the shackle line as in standard processing until the bleed time had finished. At this point, the shackle line was stopped and commercial canned expanding foam [22] was used to plug the vent of each carcass. A plastic straw was gently inserted into the vent and foam was sprayed through the straw into the colon until excess appeared. After all carcasses had been plugged with foam, they remained hanging static for an additional 10 min to allow the foam to harden; the shackle line was restarted and carcasses proceeded as in standard processing, passing through the scald before prepick sampling. Upside-Down Hang. Broilers were initially hung in the usual (leg-up) orientation and allowed to proceed along the shackle line as in standard processing. After passing through the scald tank, the shackle line was stopped, and each carcass was removed and rehung on the

3 Berrang et al.: BROILER PROCESSING MODIFICATIONS 199 shackle by the neck and wings, with the head up and the vent pointing downward. To facilitate hanging in the head-up orientation, each wing went into the leg slots of the shackle and the neck was held to the center bar with a plastic cable tie. After prepick sampling, head-up carcasses were allowed to proceed through the automated feather picker. Processing Variation Experiment 2: Prescald Evisceration. For this processing variation, broilers were housed at the University of Georgia poultry farm and inoculated with Campylobacter 1 wk before slaughter. Inoculation was by oral gavage of 1 ml of a Campylobacter jejuni cell suspension (10 9 cfu/ml) in PBS. Broilers for the control and prescald evisceration treatments were housed together in each of 3 separate pens, 1 for each replication. On arrival at the pilot plant and placement in shackles as described above, broilers were allowed to proceed along the shackle line as in standard processing until the bleed time had finished. At this point, the shackle line was stopped and carcasses were eviscerated by hand, as described above. After evisceration, the shackle line was restarted and allowed to proceed through the scald tanks before prepick sampling. Sample Collection and Bacterial Culture All carcasses were sampled by sponge wipe of the breast skin between sternal feather tracts immediately after exiting the scald tank (before entering the feather picker) and again after feather removal, as described by Berrang et al. [9]. Briefly, 3 downward swipes were made on the breast skin from the tip of the keel to the top of the breast (approximately 30 cm 2 ) by using a sterile sponge [23] premoistened with 9 ml of PBS. An additional 9 ml of PBS was added to each sponge, and all sponges were held at 4 C until cultured within 1 h. Each sponge sample was stomached for 30 s and manually squeezed to express diluent. Serial dilutions of diluent were prepared in PBS and plated in duplicate on the surface of Campy- Cefex agar (CCA) [24]. Plates were incubated for 48 h at 42 C in sealable bags flushed with microaerobic gas (5% O 2, 10% CO 2, and 85% N 2 ). One milliliter of diluent from each sample was also added to 9 ml of Campylobacter enrichment broth [25], which was incubated for 48 h at 42 C in sealable bags flushed and filled with microaerobic gas. After enrichment incubation, sterile loops were used to streak Campylobacter enrichment broth onto the surface of CCA for incubation, as described above. After incubation of the CCA plates (direct or enriched), colonies characteristic of Campylobacter were counted. Each colony type from every sample was confirmed as Campylobacter by observation of typical cellular morphology and motility on a wet mount under phase contrast microscopy. Each colony type was further confirmed as a member of the jejuni, coli, or lari species by a positive reaction on a serological latex agglutination test [26]. Statistical Analysis Three independent replications were conducted for each experiment, with 10 carcasses for each treatment (n = 30 carcasses/treatment). Colonies on duplicate plates were counted; accounting for the dilution factor, the mean number of colony-forming units per milliliter of PBS was calculated. In the case of samples in which Campylobacter was not detected by direct plating but the enrichment broth was found to be positive, a value of 1 cfu/ml was assigned. The mean number of colonies per milliliter was multiplied by the 9 ml of PBS added and log 10 transformed. Geometric means and 95% CI were calculated, and a Student s t-test was conducted to determine differences between mean numbers of Campylobacter detected on the breast skin of carcasses subjected to the various treatments [27]. Significance was assigned at P RESULTS AND DISCUSSION The numbers of Campylobacter recovered from the breast skin of broilers before and after feather removal in experiment 1 are presented in Table 1. The number of Campylobacter recovered from control carcasses increased by about 2 log units during defeathering, similar to previously published studies [8, 9, 28]. Earlier studies with vent-plugged carcasses showed significant control of Campylobacter numbers during automated feather picking [9, 14]. However, in

4 200 JAPR: Research Report Table 1. Mean log colony-forming units (±95% CI) of Campylobacter detected on broiler breast skin before and after feather removal under various processing conditions (n = 30/treatment) Campylobacter per breast skin sponge sample, log cfu Treatment 1 Prepick Postpick Difference Control 0.36 ± ± ** Prepick evisceration 1.94 ± ± Vent plug 1.00 ± ± ** Upside down 0.79 ± ± ** 1 Treatments: control = standard commercial-style broiler processing; prepick evisceration = evisceration done by hand after scalding, before feather removal; vent plug = vents plugged with commercially available expanding foam before feather removal; upside down = carcasses hung on shackles by the neck during feather removal. **P < 0.01; indicates a significant difference in Campylobacter numbers recovered on postpick carcasses relative to prepick carcasses by paired t-test. the current work, carcasses with foam-plugged vents also showed about a 2-log increase in the number of Campylobacter on the breast skin. We examined the lower gut of all foam-plugged carcasses after picking. In each group of 10 carcasses, several of the foam plugs were large and seemed to adequately block the vent. Also in each group, however, some foam plugs were forced out of the vent during feather removal and the lower gut in other carcasses appeared to be less than fully occluded, explaining why the numbers of Campylobacter still increased despite the attempt to block leakage from the vent. Carcasses that were defeathered in a head-up orientation also showed an increase in Campylobacter numbers on breast skin similar to that seen on control carcasses. Apparently, merely turning the carcass and pointing the vent downward in attempt to allow escaping gut contents to fall on the floor was not adequate to limit the spread of Campylobacter during feather removal. The most promising processing modification presented in Table 1 was prepick evisceration. This technique resulted in no measurable increase in Campylobacter numbers during defeathering. However, before defeathering, the numbers on experimental carcasses were higher (P 0.01) than on control carcasses, probably because of inadvertent contamination during hand evisceration. Therefore, although statistically significant (P 0.01), the benefit postpick was only marginal (0.63 log cfu less than on control carcasses). Further study was undertaken in an attempt to improve the performance of eviscerating before feather picking. To lower the numbers of Campylobacter on the surface of prepick eviscerated carcasses, the order of processing events was changed. Decreases in Campylobacter numbers during scalding have been reported in the literature [8, 28]. Therefore, in the current study, scalding was applied after evisceration in an effort to take advantage of the hot water to kill and wash away Campylobacter that may have spilled on the carcasses during hand evisceration. The scald tank was effective; before entering the automated feather picker, treated and control carcasses had Table 2. Mean log colony-forming units (±95% CI) of Campylobacter detected on broiler breast skin before and after feather removal after prescald evisceration (n = 30/treatment) Campylobacter per breast skin sponge sample, log cfu Treatment 1 Prepick Postpick Difference Control 0.04 ± 0.08 a 4.26 ± 0.23 a 4.22** Prescald evisceration 0.15 ± 0.18 a 1.92 ± 0.24 b 1.77** a,b Values in the same column with different superscripts are different by t-test (P < 0.01). 1 Treatments: control = standard commercial-style broiler processing; prescald evisceration = evisceration done by hand before scalding and feather removal. **P < 0.01; indicates a significant difference in Campylobacter numbers recovered on postpick carcasses relative to prepick carcasses by paired t-test.

5 Berrang et al.: BROILER PROCESSING MODIFICATIONS 201 similar numbers of breast skin Campylobacter (Table 2). During feather picking, control (uneviscerated) carcasses experienced a 4-log increase in Campylobacter numbers (Table 2). This is larger than the increase commonly reported during defeathering [8, 9, 28] and may be due to our purposeful inoculation of the live broilers. Treated (prescald eviscerated) postpick carcasses had a 99% (P 0.01) reduction in the numbers of Campylobacter compared with control carcasses (Table 2). Although Campylobacter numbers on prescald eviscerated carcasses did increase, they were far less (P < 0.01) than for carcasses processed under standard conditions. Control carcasses were processed first in this experiment, and we suspect that the increase in Campylobacter noted on treated carcasses was due to cross-contamination in the picker. Surface or airborne bacterial crosscontamination, although not as important as gut leakage for Campylobacter from naturally positive carcasses [12, 13], has been shown to occur during automated feather picking [29, 30]. CONCLUSIONS AND APPLICATIONS 1. The numbers of Campylobacter increase on breast skin during broiler carcass defeathering. 2. Commercially available canned spray foam may not consistently form an adequate vent plug to prevent the increase in Campylobacter numbers associated with the escape of feces during broiler carcass defeathering. 3. Hanging broiler carcasses with the vent down to allow escaped feces to fall on the floor rather than spread on the carcass during feather removal is not an effective means of preventing the increase in Campylobacter numbers during feather removal. 4. Changing the processing order by eviscerating broiler carcasses before scalding may be an effective means of preventing an increase in Campylobacter numbers normally observed during automated feather removal. REFERENCES AND NOTES 1. Berndtson, E., M. L. Danielsson-Tham, and A. Engvall Campylobacter incidence on a chicken farm and the spread of Campylobacter during the slaughter process. Int. J. Food Microbiol. 32: Cox, N. A., N. J. Stern, M. T. Musgrove, J. S. Bailey, S. E. Craven, P. F. Cray, R. J. Buhr, and K. L. Hiett Prevalence and level of Campylobacter in commercial broiler breeders (parents) and broilers. J. Appl. Poult. Res. 11: Bull, S. A., V. M. Allen, G. Domingue, F. Jorgensen, J. A. Frost, R. Ure, R. Whyte, D. Tinker, J. E. L. Corry, J. Gillard-King, and T. J. Humphrey Sources of Campylobacter spp. colonizing housed broiler flocks during rearing. Appl. Environ. Microbiol. 72: Zhao, C., B. Ge, J. De Villenna, R. Sudler, E. Yeh, S. Zhao, D. G. White, D. Wagner, and J. Meng Prevalence of Campylobacter spp., Escherichia coli and Salmonella serovars in retail chicken, turkey, pork and beef from the greater Washington D.C. area. Appl. Environ. Microbiol. 67: Meldrum, R. J., R. M. M. Smith, and I. G. Wilson Three year surveillance program examining the prevalence of Campylobacter and Salmonella in whole retail raw chicken. J. Food Prot. 69: Kapperud, G., G. Espeland, E. Wahl, A. Walde, H. Herikstad, S. Gustavsen, I. Tveit, O. Natas, L. Bevanger, and A. Digranes Factors associated with increased and decreased risk of Campylobacter infection: A prospective case-control study in Norway. Am. J. Epidemiol. 158: Friedman, C. R., R. M. Hoekstra, M. Samuel, R. Marcus, J. Bender, B. Shiferaw, S. Reddy, S. D. Ahuja, D. L. Helfrick, F. Hardnett, M. Carter, B. Anderson, and R. V. Tauxe Risk factors for sporadic Campylobacter infection in the United States: A case-control study in FoodNet sites. Clin. Infect. Dis. 38(Suppl. 3):S285 S Berrang, M. E., and J. A. Dickens Presence and level of Campylobacter on broiler carcasses throughout the processing plant. J. Appl. Poult. Res. 9: Berrang, M. E., R. J. Buhr, J. A. Cason, and J. A. Dickens Broiler carcass contamination with Campylobacter from feces during defeathering. J. Food Prot. 64: Berrang, M. E., R. J. Buhr, and J. A. Cason Campylobacter recovery from external and internal organs of commercial broiler carcass prior to scalding. Poult. Sci. 79: Berrang, M. E., D. P. Smith, W. R. Windham, and P. W. Feldner Effect of intestinal content contamination on broiler carcass Campylobacter counts. J. Food Prot. 67: Berrang, M. E., and J. A. Dickens The contribution of soiled surfaces within feather picking machines to Campylobacter counts on broiler carcasses. J. Appl. Poult. Res. 13: Berrang, M. E., J. K. Northcutt, and J. A. Dickens The contribution of airborne contamination to Campylobacter on defeathered carcasses. J. Appl. Poult. Res. 13:1 4.

6 202 JAPR: Research Report 14. Musgrove, M. T., J. A. Cason, D. L. Fletcher, N. J. Stern, N. A. Cox, and J. S. Bailey Effect of cloacal plugging on microbial recovery from partially processed broilers. Poult. Sci. 76: Berrang, M. E., D. P. Smith, and A. Hinton Jr Organic acids placed into the cloaca to reduce Campylobacter contamination of broiler skin during defeathering. J. Appl. Poult. Res. 15: Berrang, M. E., R. J. Buhr, J. A. Cason, and J. A. Dickens Microbiological consequences of skin removal prior to evisceration of boiler carcasses. Poult. Sci. 81: Bashor, M. P., P. A. Curtis, K. M. Keener, B. W. Sheldon, S. Kathariou, and J. A. Osborne Effects of carcass washers on Campylobacter contamination in large broiler processing plants. Poult. Sci. 83: Stunner Model SF-7000, Simmons Engineering Co., Dallas, GA. 19. Killer Model SK.5, Simmons Engineering Co., Dallas, GA. 20. Scald Tank Model SGS-3CA, Stork Gamco, Gainesville, GA. 21. Picker Model D-8, Stork Gamco, Gainesville, GA. 22. Greatstuff, Dow Chemical Co., Midland, MI cm, Nasco, Fort Atkinson WI. 24. Stern, N. J., B. Wojton, and K. Kwiatek A differential selective medium and dry ice generated atmosphere for recovery of Campylobacter jejuni. J. Food Prot. 55: Acumedia Manufacturers, Baltimore, MD. 26. Microgen Bioproducts Limited, Camberley, Surrey, UK. 27. Paired t-tests were used to compare mean numbers of Campylobacter recovered from breast skin of the same carcass before and after feather picking. Unpaired t-tests were used to compare mean numbers recovered from carcasses subjected to different treatments. 28. Izat, A. L., F. A. Gardner, J. H. Denton, and F. A. Golan Incidence and level of Campylobacter jejuni in broiler processing. Poult. Sci. 67: Mead, G. C., W. R. Hudson, and M. H. Hinton Use of a marker organism in poultry processing to identify sites of cross-contamination and evaluate possible control measures. Br. Poult. Sci. 35: Nde, C. W., J. M. McEvot, J. S. Sherwood, and C. M. Logue Cross contamination of turkey carcasses by Salmonella species during defeathering. Poult. Sci. 86: Acknowledgments The authors gratefully acknowledge expert technical assistance by the following from the USDA-ARS-Russell Research Center (Athens, GA): Eric Adams, Shayla Hunter, Sandra House, Jeromey Jackson, Jerrie Barnett, Denice Cudnik, and Winston Wright.