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Organic Acids Placed into the Cloaca to Reduce Campylobacter Contamination of Broiler Skin During Defeathering1
2006 Poultry Science Association, Inc.
Organic Acids Placed into the Cloaca to Reduce Campylobacter Contamination of Broiler Skin During Defeathering1 M. E. Berrang,2 D. P. Smith, and A. Hinton Jr. USDA-Agricultural Research Service, Russell Research Center, Athens, GA 30604-5677
SUMMARY Campylobacter numbers on broiler carcasses can increase dramatically during defeathering because of leakage of contaminated gut contents in the feather-picking machine. Food-grade organic acids have been shown to be effective in killing bacteria. Placement of organic acids into the cloaca prior to defeathering was tested to determine if such a treatment could lower the number of Campylobacter that escape and contaminate broiler breast skin during automated feather removal. Campylobacter numbers on the breast skin of treated carcasses increased during defeathering but resulted in numbers that were only about 2% of those observed on control carcasses. Placement of food-grade organic acids in the cloaca of broiler carcasses may be useful as a means to lessen the impact of automated defeathering on the microbiological quality of carcasses during processing. Key words: Campylobacter, defeathering, acetic acid, lactic acid, proprionic acid, organic acid 2006 J. Appl. Poult. Res. 15:287–291
DESCRIPTION OF PROBLEM Overall, processing lowers the numbers of Campylobacter on broiler carcasses such that a chilled carcass has fewer bacteria than a prescald carcass [1, 2]. However, one processing step causes a dramatic increase in Campylobacter numbers detected on broiler carcass skin. Automated defeathering has been shown to cause contents to be released from the cloaca [3]. In the case of Campylobacter-positive flocks, this causes a significant increase in the numbers of Campylobacter associated with the outer surfaces of the carcass [1, 2, 3]. Lessening this increase could enable processors to reduce the numbers of Campylobacter on finished products, 1
which would potentially result in less risk of foodborne campylobacteriosis to the consumer. Organic acids have been used to improve the microbiological quality of food products, including meat. When applied to beef as a spray treatment, organic acids have been shown to lower numbers of bacteria recovered from the surface of carcasses [4, 5, 6, 7, 8]. Organic acids have also been tested to reduce bacteria during poultry processing. Spraying broiler carcasses with lactic acid lowers the numbers of salmonellae that can be recovered [9, 10, 11]. Organic acids have also been shown to be effective in lowering some bacterial numbers recovered from poultry carcasses when used in scald water [12], as a spray during defeathering [13], during
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 US Department of Agriculture. 2 Corresponding author: [email protected]
Downloaded from http://japr.oxfordjournals.org/ at University of Manchester on April 13, 2015
Primary Audience: Food Safety Researchers, Quality Assurance Personnel
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MATERIALS AND METHODS Experimental Design and Treatments Organic acids were used at 1 M concentration and included acetic acid (pH 2.3), lactic acid (pH 1.9), and proprionic acid (pH 2.4) [19]. In each of 3 replicate trials, 10 carcasses were treated with each acid, and another 10 were treated with sterile water as a control (n = 30 carcasses per treatment; n = 120). Treatment was applied after bleed-out and before carcasses entered the scald tank. Campylobacter numbers on carcass breast skin was determined at 2 points: after scalding but before entering the feather picker and again after passage through the feather picker. Campylobacter numbers recovered at the 2 sample points were compared to measure the effectiveness of each treatment in lowering the expected increase during feather removal.
Broilers and Processing Live broilers (approximately 42 d old) were obtained from a commercial processing plant after approximately 12 h of feed withdrawal, caged in plastic coops, and then transported to a pilot processing facility. Broilers were held at room temperature (approximately 25 to 30°C) until hung in groups of 10 in commercial-style shackles. All broilers were stunned electrically by 12 V DC [20] and killed by cutting blood vessels in the neck with an automated killing machine [21]. The line was stopped for approximately 2 min to apply treatment to carcasses. First, each carcass was subjected to a manual squeeze to express contents from the cloaca. The intent was to avoid variation due to some carcasses having much more cloacal contents than others. Each carcass was then subjected to the acid or watercontrol treatment. Liquid was placed into the cloaca by means of a sterile 25-mL pipette and a hand held pipette aid pump [22]. Each pipette was inserted gently until resistance was met (approximately 3 cm), and 12 mL of acid or water was pumped into the cloaca. The goal of the treatment was to fill each cloaca up to overflowing, assuring the maximum uptake possible under the conditions described. Upon removal of the pipette, the vent was briefly (1 to 2 s) held shut to minimize leakage of the treatment chemical. Leakage indicated the cloaca was full and was not quantified. The shackle line was restarted, and the carcasses progressed to the scald tank. Carcasses were scalded in a set of 3 triplepass scald tanks [23] set at 56°C. Shackle speed was set so that carcasses spent 30 s in each scald tank with 30 s in between. The time required for carcasses to proceed from the killer to scald tank exit, including application of treatment, was approximately 6.5 min. Each carcass was sampled after scalding. Carcasses then proceeded into a commercial defeathering machine [24] operated with a tap water spray (average total chlorine of 0.5 ppm). A paired sample from each carcass was collected after defeathering. In between each batch of 10 broilers, the feather-picking machine was sanitized. First the machine was subjected to a thorough hose washing with 52°C water. Then each picker finger
Downloaded from http://japr.oxfordjournals.org/ at University of Manchester on April 13, 2015
prechill [12, 14], or as a postchill dip [12]. When applied in combination with modified atmosphere packaging, lactic acid treatment has been shown to result in increased shelf life of fresh poultry meat [15, 16]. Tamblyn and Conner [17] examined the relationship between exposure time and concentration on the effectiveness of several organic acids to inactivate Salmonella attached to chicken skin. They found that attached salmonellae were harder to kill than suspended cells and that greater than 4% concentration of acid was required to cause a 2 log decrease in the number of cells attached to chicken skin [17]. Hinton et al. [18] found that by feeding lactose to young chickens, the pH of the ceca changed as the concentration of lactic acid increased. They found that chicks provided with dietary lactose had fewer Salmonella in their ceca [18]. These findings suggest that organic acids may be effective to kill bacteria in the gut as well as on the outer surfaces of carcasses. The objective of the current study was to test the effect of organic acids placed in the cloaca before scalding on the numbers of Campylobacter found on carcass breast skin after automated defeathering. Our hypothesis was that acid treatment (acetic, lactic, or proprionic) would lower the number of viable Campylobacter in the cloaca of broiler carcasses, resulting in less contamination due to leakage during defeathering.
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Table 1. Effect of organic acids placed in the cloaca of broiler carcasses prescald on the recovery of Campylobacter (log10 cfu/sponge sample) from carcass breast skin sampled before and after defeathering (n = 30 per treatment) Treatment Water control 1 M acetic acid 1 M lactic acid 1 M proprionic acid
Before defeathering 0.53A,X 0.65A,X 0.10B,X 0.41AB,X
± ± ± ±
After defeathering 4.01A,Y 2.10B,Y 2.35B,Y 2.38B,Y
0.33 0.33 0.14 0.29
± ± ± ±
0.23 0.34 0.24 0.22
A,B Values within the same column with different superscripts are significantly different by Tukey’s honest significant difference (P < 0.01). X,Y Values within the same row with different superscripts are significantly different by paired t-test (P < 0.01).
Carcass Sampling To quantify the increase in Campylobacter numbers recovered from carcass skin due to passage through the feather-picking machine, carcasses were sampled immediately before and after defeathering. Each carcass was sampled by means of a sponge swipe of the breast skin between sternal feather tracts as described by Berrang et al. [3]. Briefly, 3 downward swipes were made on the breast skin from the tip of the keel to the top of the breast (approximately 30 cm2) by using a sterile sponge [25] premoistened with 10 mL of PBS. An additional 10 mL of PBS was added to each sponge, and all sponges were held at 4°C until cultured within 1 h. Bacterial Culture 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 campycefex agar [26]. Plates were incubated 48 h at 42°C in sealable bags flushed with microaerobic gas (5% O2, 10% CO2, and 85% N2). Preliminary work (data not shown) revealed that moistened skin sponge samples from acidtreated carcasses had a pH between 6.5 and 7.5, well within the range that Campylobacter tolerates [27]. Therefore, Campylobacter would not be expected to die in the sample after collection. Nevertheless, it was desired to assure that any reduction in numbers was due to treatment rather than sample handling. After removal of the aliquot for plating, the pH of each sample from
acid-treated carcasses was measured with test paper [28]. After incubation, 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 jejuni, coli, or lari species by a positive reaction on a serological latex agglutination test [29]. Statistical Analysis Number of Campylobacter detected per sample was log10 transformed and analyzed with a statistical software package [30]. The data were analyzed in 2 different ways. We tested to determine if Campylobacter counts increased during defeathering as expected. A paired t-test was conducted to test for differences in numbers detected on the same breast skin before and after feather removal. A separate test was done for differences in mean numbers within sample site according to treatment. This was done with an ANOVA using a randomized complete block design with replication as the block. This method removes the replication effect and places it in the error term resulting in a robust test of treatment. The ANOVA was followed by Tukey’s honest significant difference test to separate means by treatment. Significance was assigned at P < 0.01 for all tests.
RESULTS AND DISCUSSION Preliminary study (data not shown) indicated that addition of 12 mL of 1 M acetic, lactic, or proprionic acid to the cloaca of broiler carcasses lowered numbers of viable Campylobacter that
Downloaded from http://japr.oxfordjournals.org/ at University of Manchester on April 13, 2015
was sprayed with 200 ppm sodium hypochlorite, and the machine was rinsed again with 52°C water.
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significantly lower than the numbers detected on control carcasses. None of the 3 acid treatments was better than the others in lessening the final number of Campylobacter on defeathered carcasses. They all resulted in numbers equal to about 1 to 2% of that observed on the skin of control carcasses. Reductions in bacterial numbers due to application of organic acids directly to the surface of broiler carcasses [9, 10, 11, 12, 13, 14] and meat [15, 16] have been shown previously. In some instances, these treatments resulted in a negative change in skin color and texture [12, 14]. However, in the current study acids were not applied directly to the carcass surface, and, although no readings were taken on a colorimeter, no change in skin color was noted. We have shown that application of organic acid to the cloaca prior to scalding results in less Campylobacter contamination during defeathering. Practical use of this type of treatment in a commercial setting would require an engineering solution for application. If the mechanical logistics were solved, such a treatment would be expected to result in lower Campylobacter numbers being on the skin prior to the use of an inside-outside washer and other interventions commonly used in poultry processing. It is our hope that by lowering the numbers of Campylobacter on defeathered carcasses, processors will be able to produce chilled carcasses with lower numbers of Campylobacter.
CONCLUSIONS AND APPLICATIONS 1. The increase in Campylobacter numbers on broiler carcasses during defeathering was reaffirmed. 2. Application of 12 mL of 1 M acetic acid, lactic acid, or proprionic acid into the cloaca of a carcass before scalding resulted in lower numbers of Campylobacter on carcasses (breast skin) after defeathering. 3. If a delivery system to apply food-grade organic acids to the cloaca of broiler carcasses prior to scald could be engineered, Campylobacter contamination of defeathered carcasses might be lessened.
REFERENCES AND NOTES 1. Izat, A. L., F. A. Gardner, J. H. Denton, and F. A. Golan. 1988. Incidence and level of Campylobacter jejuni in broiler processing. Poult. Sci. 67:1568–1572. 2. Berrang, M. E., and J. A. Dickens. 2000. Presence and level of Campylobacter on broiler carcasses throughout the processing plant. J. Appl. Poult. Res. 9:43–47.
3. Berrang, M. E., R. J. Buhr, J. A. Cason, and J. A. Dickens. 2001. Broiler carcass contamination with Campylobacter from feces during defeathering. J. Food Prot. 64:2063–2066. 4. Bell, K. Y., C. N. Cutter, and S. S. Sumner. 1997. Reduction of foodborne micro-organisms on beef carcass tissue using acetic
Downloaded from http://japr.oxfordjournals.org/ at University of Manchester on April 13, 2015
could be recovered by cloacal swab. However, the pH of the cloacal swab samples was affected by the addition of the acid. This finding suggested that the Campylobacter on cloacal swabs might have been dying, not just in the gut, but also after collection due to the harsh conditions in the sample tube. To test for the possibility of death after sample collection in the current study, the pH of each breast skin sponge sample collected from acid treated carcasses was tested and found to fall between pH 6.5 and 7.5, which is within the range that Campylobacter can tolerate [27]. Therefore, continued death of Campylobacter due to low pH of the sample after collection was not considered to be a problem. Campylobacter numbers are shown in Table 1. All prepick breast sponge samples had less than 1 log cfu Campylobacter. Prepick samples from the carcasses treated with lactic acid had slightly lower numbers than the prepick samples from carcasses that were treated with water or the other acids. Water-treated control carcasses underwent a 3.5 log increase in the numbers of Campylobacter recovered due to passage through the feather-picking machine. This result was similar to increases in Campylobacter numbers that have been previously reported [1, 2]. Carcasses that had been treated with acids also had increased numbers of Campylobacter recovered from breast skin due to defeathering. However, this increase was not as dramatic and resulted in counts around 2 log cfu per sample and was
BERRANG ET AL.: ACIDS IN THE VENT acid, sodium bicarbonate, and hydrogen peroxide spray washes. Food Microbiol. 14:439–448. 5. Dorsa, W. J., C. N. Cutter, and G. R. Siragusa. 1997. Effects of acetic acid, lactic acid and trisodium phosphate on the microflora of refrigerated beef carcass surface tissue inoculated with Escherichia coli 0157:H7, Listeria innocua, and Clostridium sporogenes. J. Food Prot. 60:619–624.
291 15. Zeitoun, A. A. M., and J. M. Debevere. 1992. Decontamination with lactic acid/sodium lactate buffer in combination with modified atmosphere packaging effects on the shelf life of fresh poultry. Int. J. Food Microbiol. 16:89–98. 16. Jimenez, S. M., M. S. Salsi, M. C. Tiburzi, R. C. Rafaghelli, and M. E. Pirovani. 1999. Combined use of acetic acid treatment and modified atmosphere packaging for extending the shelf-life of chilled chicken breast portions. J. Appl. Microbiol. 87:339–344.
6. Castillo, A., L. M. Lucia, K. J. Goodson, J. W. Savell, and G. R. Acuff. 1998. Comparison of water wash, trimming, and combined hot water and lactic acid treatments for reducing bacteria of fecal origin on beef carcasses. J. Food Prot. 61:823–828.
17. Tamblyn, K. C., and D. A. Conner. 1997. Bactericidal activity of organic acids against Salmonella typhimurium attached to broiler chicken skin. J. Food Prot. 60:629–633.
7. Castillo, A., L. M. Lucia, K. J. Goodson, J. W. Savell, and G. R. Acuff. 1999. Decontamination of beef carcass surface tissue by steam vacuuming alone and combined with hot water and lactic acid sprays. J. Food Prot. 62:146–151.
18. Hinton, A., Jr., D. E. Corrier, G. E. Spates, J. O. Norman, R. L. Ziprin, R. C. Beier, and J. R. Deloach. 1990. Biological control of Salmonella typhimurium in young chickens. Avian Dis. 34:626–633.
9. Li, Y., M. F. Slavik, J. T. Walker, and H. Xiong. 1997. Prechill spray of chicken carcasses to reduce Salmonella typhimurium. J. Food Sci. 62:605–607. 10. Xiong, H., Y. Li, M. F. Slavik, and J. T. Walker. 1998. Spraying chicken skin with selected chemicals to reduce attached Salmonella typhimurium. J. Food Prot. 61:272–275. 11. Yang, Z., Y. Li, and M. F. Slavik. 1998. Use of antimicrobial spray applied with an inside outside birdwasher to reduce bacterial contamination on prechilled chicken carcasses. J. Food Prot. 61:829–832. 12. Izat, A. L., M. Colberg, R. A. Thomas, M. H. Adams, and C. D. Driggers. 1990. Effects of lactic acid in processing waters on the incidence of salmonellae on broilers. J. Food Qual. 13:295–306.
19. Sigma Chemical Co., St. Louis, MO. 20. Stunner Model SF-7000, Simmons Engineering Co., Dallas, GA. 21. Killer Model SK.5, Simmons Engineering Co. 22. Pipette aid, Drummond Scientific Co., Broomall, PA. 23. Scald tank Model SGS-3CA, Stork Gamco, Gainesville, GA. 24. Picker Model D-8, Stork Gamco. 25. 18-oz Speci-sponge, Nasco, Fort Atkinson, WI. 26. Stern, N. J., B. Wojton, and K. Kwiatek. 1992. A differential selective medium and dry ice generated atmosphere for recovery of Campylobacter jejuni. J. Food Prot. 55:514–517. 27. Jay, J. M. 2000. Modern Food Microbiology. 6th ed. Aspen, Gaithersburg, MD. 28. Baker pHIX, Mallincrodt and Baker Inc., Phillipsburg, NJ.
13. Dickens, J. A., and A. D. Whittemore. 1997. Effects of acetic acid and hydrogen peroxide application during defeathering on the microbiological quality of broiler carcasses prior to evisceration. Poult. Sci. 76:657–660.
29. Microscreen Campylobacter, Microgen Bioprodcuts Ltd., Camberly, UK.
14. Dickens, J. A., and A. D. Whittemore. 1994. The effect of acetic acid and air injection on appearance moisture pickup, microbiological quality, and Salmonella incidence on processed poultry carcasses. Poult. Sci. 73:582–586.
Acknowledgments
30. Stat soft, Tulsa, OK.
The authors thank Mark N. Freeman, V. Allan Savage, and Steven A. Lyon for expert technical assistance.
Downloaded from http://japr.oxfordjournals.org/ at University of Manchester on April 13, 2015
8. Cutter, C. N. 1999. Combination spray washes of saponin with water or acetic acid to reduce aerobic and pathogenic bacteria on lean beef surfaces. J. Food Prot. 62:280–283.
Organic Acids Placed into the Cloaca to Reduce Campylobacter Contamination of Broiler Skin During Defeathering1 M. E. Berrang,2 D. P. Smith, and A. Hinton Jr. USDA-Agricultural Research Service, Russell Research Center, Athens, GA 30604-5677
SUMMARY Campylobacter numbers on broiler carcasses can increase dramatically during defeathering because of leakage of contaminated gut contents in the feather-picking machine. Food-grade organic acids have been shown to be effective in killing bacteria. Placement of organic acids into the cloaca prior to defeathering was tested to determine if such a treatment could lower the number of Campylobacter that escape and contaminate broiler breast skin during automated feather removal. Campylobacter numbers on the breast skin of treated carcasses increased during defeathering but resulted in numbers that were only about 2% of those observed on control carcasses. Placement of food-grade organic acids in the cloaca of broiler carcasses may be useful as a means to lessen the impact of automated defeathering on the microbiological quality of carcasses during processing. Key words: Campylobacter, defeathering, acetic acid, lactic acid, proprionic acid, organic acid 2006 J. Appl. Poult. Res. 15:287–291
DESCRIPTION OF PROBLEM Overall, processing lowers the numbers of Campylobacter on broiler carcasses such that a chilled carcass has fewer bacteria than a prescald carcass [1, 2]. However, one processing step causes a dramatic increase in Campylobacter numbers detected on broiler carcass skin. Automated defeathering has been shown to cause contents to be released from the cloaca [3]. In the case of Campylobacter-positive flocks, this causes a significant increase in the numbers of Campylobacter associated with the outer surfaces of the carcass [1, 2, 3]. Lessening this increase could enable processors to reduce the numbers of Campylobacter on finished products, 1
which would potentially result in less risk of foodborne campylobacteriosis to the consumer. Organic acids have been used to improve the microbiological quality of food products, including meat. When applied to beef as a spray treatment, organic acids have been shown to lower numbers of bacteria recovered from the surface of carcasses [4, 5, 6, 7, 8]. Organic acids have also been tested to reduce bacteria during poultry processing. Spraying broiler carcasses with lactic acid lowers the numbers of salmonellae that can be recovered [9, 10, 11]. Organic acids have also been shown to be effective in lowering some bacterial numbers recovered from poultry carcasses when used in scald water [12], as a spray during defeathering [13], during
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 US Department of Agriculture. 2 Corresponding author: [email protected]
Downloaded from http://japr.oxfordjournals.org/ at University of Manchester on April 13, 2015
Primary Audience: Food Safety Researchers, Quality Assurance Personnel
JAPR: Research Report
288
MATERIALS AND METHODS Experimental Design and Treatments Organic acids were used at 1 M concentration and included acetic acid (pH 2.3), lactic acid (pH 1.9), and proprionic acid (pH 2.4) [19]. In each of 3 replicate trials, 10 carcasses were treated with each acid, and another 10 were treated with sterile water as a control (n = 30 carcasses per treatment; n = 120). Treatment was applied after bleed-out and before carcasses entered the scald tank. Campylobacter numbers on carcass breast skin was determined at 2 points: after scalding but before entering the feather picker and again after passage through the feather picker. Campylobacter numbers recovered at the 2 sample points were compared to measure the effectiveness of each treatment in lowering the expected increase during feather removal.
Broilers and Processing Live broilers (approximately 42 d old) were obtained from a commercial processing plant after approximately 12 h of feed withdrawal, caged in plastic coops, and then transported to a pilot processing facility. Broilers were held at room temperature (approximately 25 to 30°C) until hung in groups of 10 in commercial-style shackles. All broilers were stunned electrically by 12 V DC [20] and killed by cutting blood vessels in the neck with an automated killing machine [21]. The line was stopped for approximately 2 min to apply treatment to carcasses. First, each carcass was subjected to a manual squeeze to express contents from the cloaca. The intent was to avoid variation due to some carcasses having much more cloacal contents than others. Each carcass was then subjected to the acid or watercontrol treatment. Liquid was placed into the cloaca by means of a sterile 25-mL pipette and a hand held pipette aid pump [22]. Each pipette was inserted gently until resistance was met (approximately 3 cm), and 12 mL of acid or water was pumped into the cloaca. The goal of the treatment was to fill each cloaca up to overflowing, assuring the maximum uptake possible under the conditions described. Upon removal of the pipette, the vent was briefly (1 to 2 s) held shut to minimize leakage of the treatment chemical. Leakage indicated the cloaca was full and was not quantified. The shackle line was restarted, and the carcasses progressed to the scald tank. Carcasses were scalded in a set of 3 triplepass scald tanks [23] set at 56°C. Shackle speed was set so that carcasses spent 30 s in each scald tank with 30 s in between. The time required for carcasses to proceed from the killer to scald tank exit, including application of treatment, was approximately 6.5 min. Each carcass was sampled after scalding. Carcasses then proceeded into a commercial defeathering machine [24] operated with a tap water spray (average total chlorine of 0.5 ppm). A paired sample from each carcass was collected after defeathering. In between each batch of 10 broilers, the feather-picking machine was sanitized. First the machine was subjected to a thorough hose washing with 52°C water. Then each picker finger
Downloaded from http://japr.oxfordjournals.org/ at University of Manchester on April 13, 2015
prechill [12, 14], or as a postchill dip [12]. When applied in combination with modified atmosphere packaging, lactic acid treatment has been shown to result in increased shelf life of fresh poultry meat [15, 16]. Tamblyn and Conner [17] examined the relationship between exposure time and concentration on the effectiveness of several organic acids to inactivate Salmonella attached to chicken skin. They found that attached salmonellae were harder to kill than suspended cells and that greater than 4% concentration of acid was required to cause a 2 log decrease in the number of cells attached to chicken skin [17]. Hinton et al. [18] found that by feeding lactose to young chickens, the pH of the ceca changed as the concentration of lactic acid increased. They found that chicks provided with dietary lactose had fewer Salmonella in their ceca [18]. These findings suggest that organic acids may be effective to kill bacteria in the gut as well as on the outer surfaces of carcasses. The objective of the current study was to test the effect of organic acids placed in the cloaca before scalding on the numbers of Campylobacter found on carcass breast skin after automated defeathering. Our hypothesis was that acid treatment (acetic, lactic, or proprionic) would lower the number of viable Campylobacter in the cloaca of broiler carcasses, resulting in less contamination due to leakage during defeathering.
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Table 1. Effect of organic acids placed in the cloaca of broiler carcasses prescald on the recovery of Campylobacter (log10 cfu/sponge sample) from carcass breast skin sampled before and after defeathering (n = 30 per treatment) Treatment Water control 1 M acetic acid 1 M lactic acid 1 M proprionic acid
Before defeathering 0.53A,X 0.65A,X 0.10B,X 0.41AB,X
± ± ± ±
After defeathering 4.01A,Y 2.10B,Y 2.35B,Y 2.38B,Y
0.33 0.33 0.14 0.29
± ± ± ±
0.23 0.34 0.24 0.22
A,B Values within the same column with different superscripts are significantly different by Tukey’s honest significant difference (P < 0.01). X,Y Values within the same row with different superscripts are significantly different by paired t-test (P < 0.01).
Carcass Sampling To quantify the increase in Campylobacter numbers recovered from carcass skin due to passage through the feather-picking machine, carcasses were sampled immediately before and after defeathering. Each carcass was sampled by means of a sponge swipe of the breast skin between sternal feather tracts as described by Berrang et al. [3]. Briefly, 3 downward swipes were made on the breast skin from the tip of the keel to the top of the breast (approximately 30 cm2) by using a sterile sponge [25] premoistened with 10 mL of PBS. An additional 10 mL of PBS was added to each sponge, and all sponges were held at 4°C until cultured within 1 h. Bacterial Culture 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 campycefex agar [26]. Plates were incubated 48 h at 42°C in sealable bags flushed with microaerobic gas (5% O2, 10% CO2, and 85% N2). Preliminary work (data not shown) revealed that moistened skin sponge samples from acidtreated carcasses had a pH between 6.5 and 7.5, well within the range that Campylobacter tolerates [27]. Therefore, Campylobacter would not be expected to die in the sample after collection. Nevertheless, it was desired to assure that any reduction in numbers was due to treatment rather than sample handling. After removal of the aliquot for plating, the pH of each sample from
acid-treated carcasses was measured with test paper [28]. After incubation, 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 jejuni, coli, or lari species by a positive reaction on a serological latex agglutination test [29]. Statistical Analysis Number of Campylobacter detected per sample was log10 transformed and analyzed with a statistical software package [30]. The data were analyzed in 2 different ways. We tested to determine if Campylobacter counts increased during defeathering as expected. A paired t-test was conducted to test for differences in numbers detected on the same breast skin before and after feather removal. A separate test was done for differences in mean numbers within sample site according to treatment. This was done with an ANOVA using a randomized complete block design with replication as the block. This method removes the replication effect and places it in the error term resulting in a robust test of treatment. The ANOVA was followed by Tukey’s honest significant difference test to separate means by treatment. Significance was assigned at P < 0.01 for all tests.
RESULTS AND DISCUSSION Preliminary study (data not shown) indicated that addition of 12 mL of 1 M acetic, lactic, or proprionic acid to the cloaca of broiler carcasses lowered numbers of viable Campylobacter that
Downloaded from http://japr.oxfordjournals.org/ at University of Manchester on April 13, 2015
was sprayed with 200 ppm sodium hypochlorite, and the machine was rinsed again with 52°C water.
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significantly lower than the numbers detected on control carcasses. None of the 3 acid treatments was better than the others in lessening the final number of Campylobacter on defeathered carcasses. They all resulted in numbers equal to about 1 to 2% of that observed on the skin of control carcasses. Reductions in bacterial numbers due to application of organic acids directly to the surface of broiler carcasses [9, 10, 11, 12, 13, 14] and meat [15, 16] have been shown previously. In some instances, these treatments resulted in a negative change in skin color and texture [12, 14]. However, in the current study acids were not applied directly to the carcass surface, and, although no readings were taken on a colorimeter, no change in skin color was noted. We have shown that application of organic acid to the cloaca prior to scalding results in less Campylobacter contamination during defeathering. Practical use of this type of treatment in a commercial setting would require an engineering solution for application. If the mechanical logistics were solved, such a treatment would be expected to result in lower Campylobacter numbers being on the skin prior to the use of an inside-outside washer and other interventions commonly used in poultry processing. It is our hope that by lowering the numbers of Campylobacter on defeathered carcasses, processors will be able to produce chilled carcasses with lower numbers of Campylobacter.
CONCLUSIONS AND APPLICATIONS 1. The increase in Campylobacter numbers on broiler carcasses during defeathering was reaffirmed. 2. Application of 12 mL of 1 M acetic acid, lactic acid, or proprionic acid into the cloaca of a carcass before scalding resulted in lower numbers of Campylobacter on carcasses (breast skin) after defeathering. 3. If a delivery system to apply food-grade organic acids to the cloaca of broiler carcasses prior to scald could be engineered, Campylobacter contamination of defeathered carcasses might be lessened.
REFERENCES AND NOTES 1. Izat, A. L., F. A. Gardner, J. H. Denton, and F. A. Golan. 1988. Incidence and level of Campylobacter jejuni in broiler processing. Poult. Sci. 67:1568–1572. 2. Berrang, M. E., and J. A. Dickens. 2000. Presence and level of Campylobacter on broiler carcasses throughout the processing plant. J. Appl. Poult. Res. 9:43–47.
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Acknowledgments
30. Stat soft, Tulsa, OK.
The authors thank Mark N. Freeman, V. Allan Savage, and Steven A. Lyon for expert technical assistance.
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