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J APPL POULT RES 2008. 17:272-277. doi:10.3382/japr.2007-00108
© 2008 Poultry Science Association
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Research Reports

Effect of Sand and Shaking Duration on the Recovery of Aerobic Bacteria, Coliforms, and Escherichia coli from Prechill Broiler Whole Carcass Rinsates1

J. F. Hannah*, D. L. Fletcher*,2, N. A. Cox{dagger}, D. P. Smith{ddagger}, J. A. Cason§, J. K. Northcutt§, L. J. Richardson{dagger} and R. J. Buhr{dagger},3

* Department of Poultry Science, University of Georgia, Athens 30602; {dagger} Poultry Microbiological Safety, {ddagger} Quality and Safety Assessment, and § Poultry Processing and Swine Physiology Research Units, Richard B. Russell Agricultural Research Center, USDA-ARS, PO Box 5677, Athens, GA 30604-5677

3 Corresponding author: jeff.buhr{at}ars.usda.gov


   SUMMARY
TOP
 SUMMARY
DESCRIPTION OF PROBLEM
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 CONCLUSIONS AND APPLICATIONS
 REFERENCES AND NOTES
 
Broilers entering a processing facility can be contaminated with bacteria internally, externally, or both, and additional contamination may occur during processing. Although processing generally reduces the bacterial load on a carcass, it does not eliminate all carcass bacterial contaminants. Processing plant personnel sample carcasses daily to determine overall carcass contamination using the whole carcass rinse procedure. The objective of this study was to evaluate the potential benefit of adding sand to the whole carcass rinse and extending shaking (rinsing) duration on the recovery of bacteria from broiler carcasses. Eviscerated broiler carcasses were obtained from a commercial processing plant before the prechill final wash. Carcasses were rinsed in peptone or peptone with sand for 1 and 4 min. Rinsates were analyzed for aerobic plate count, coliforms, and Escherichia coli. Bacterial levels recovered from rinsates with sand were significantly higher than levels recovered from the peptone-only rinsates, but the increase in recovery was relatively small at 0.6 log10 cfu/mL of rinsate. There was no significant improvement in bacterial recovery when shaking duration was increased from 1 to 4 min for either rinse treatment.

Key Words: whole carcass rinse • sand • coliform • Escherichia coli • aerobic plate count


   DESCRIPTION OF PROBLEM
TOP
 SUMMARY
 DESCRIPTION OF PROBLEM
MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 CONCLUSIONS AND APPLICATIONS
 REFERENCES AND NOTES
 
Live broilers typically enter the processing facility externally contaminated with various microorganisms [1], and during processing, additional contamination can result from bird debris, fecal material, crop contents, and carcass-to-carcass contact [2]. There have been more than 50 different genera of bacteria recovered from processed poultry carcasses [3, 4], and several methods have been used to recover bacteria from carcasses. Common sampling methods include whole carcass rinsing, swabbing, and skin excision followed by stomaching or blending [5, 6]. There are conflicting results regarding which of these methods offers the best estimate of bacterial levels on an entire carcass [2, 6, 7]. Modifications to the sampling methods are often made in attempts to better understand bacterial recovery from carcasses and the overall carcass bacterial contamination level.

Most carcass bacteria are suspended in a thin aqueous layer that forms on the carcass after going through several spray washes and immersion chilling [8]. Bacteria within this layer are readily removed from the carcass and are commonly sampled by whole carcass rinsing [9]. However, a portion of the bacteria remains adhered to the carcass surface and may form irreversible attachments [10–13]. Bacteria are able to remain on broiler skin through agitated chilling for 60 min and are commonly located within channels and crevices of the skin surface [14, 15]. Only after inoculation challenges have bacteria been located within the empty feather follicles of processed broiler skin [16]. Recently, Buhr et al. [17, 18] and Cason et al. [19] used a strain of genetically featherless broiler chickens and demonstrated that the presence of empty feather follicles in the skin of processed broiler carcasses was not a significant factor in overall carcass bacterial contamination levels.

The whole carcass rinse (WCR) procedure involves shaking a carcass for 1 min in 100 to 1,000 mL of rinse fluid and is a practical method for sampling and recovering bacteria. Swabbing and skin excision methods are used to dislodge those bacteria loosely adhering to the surface of the skin. After testing the efficacy of 5 sampling methods (cotton and calcium alginate swabbing, spot plating, tissue sampling, and carcass rinsing), Fromm [20] concluded that a scrubbing action was needed to dislodge the loosely adhered bacteria from a carcass into the rinsate. Patterson and Stewart [21] incorporated coarse sand into their rinse sampling procedures for excised skin, but they did not include a control group without sand to determine if the sand increased the number of bacteria recovered in the rinsate. In another study, Patterson [22] rinsed skin samples with sand added to the rinse on the assumption that it would improve bacterial recovery but also did not include a control to test that assumption. Sand has been incorporated into the WCR procedure to overcome the potential of the skin surface oil to restrict bacterial removal from carcasses displaying signs of oily bird syndrome [23]. Because sand was added to both the control and the oily bird syndrome carcasses, it was not possible to evaluate any beneficial effect of the sand. Cox et al. [24] used sterile glass beads as an added scrubbing agent in excised skin rinses and found that the addition of the beads significantly increased the recovery of total bacteria and Enterobacteriaceae from fresh carcass skin samples but only by 0.2 log10 cfu/cm2. The increase in rinsate recovery with added beads was statistically significant, although of minimal biological significance.

Research has determined the effects of shaking duration on bacterial recovery [24]; however, those experiments did not test if shaking duration was a significant factor when sand was added to the rinse. These experiments were conducted to evaluate the potential benefits of sand added to the rinse and increasing shaking duration from 1 to 4 min on aerobic plate count (APC), coliform, and Escherichia coli recovery from whole carcass rinsates.


   MATERIALS AND METHODS
TOP
 SUMMARY
 DESCRIPTION OF PROBLEM
 MATERIALS AND METHODS
RESULTS AND DISCUSSION
 CONCLUSIONS AND APPLICATIONS
 REFERENCES AND NOTES
 
Sample Collection
Twelve prechill broiler carcasses were obtained from a commercial processing plant on each of 4 replication days. Carcasses were collected before the inside-outside carcass washer and before any treatment with antimicrobials, other than incidental spraying with chlorinated water at 20 ppm. Each carcass was aseptically removed from the processing line, placed into a clean individual plastic bag, and transported to the lab in an ice chest. Carcasses were tagged for identification, transferred to new clean plastic bags, and placed into 1 of 2 treatment groups. In each of the replications, 6 carcasses were rinsed in 400 mL of sterile 2.0% buffered peptone [25] for 1 min in a mechanical carcass shaker [26]. The remaining 6 carcasses were shaken in the same manner but with 100 g of sterile (autoclaved for 15 min) sand added to the rinse solution. After 1 min of shaking, a 10-mL aliquot was collected from each rinsate for sampling, and then 10 mL of sterile buffered peptone was added back to each carcass rinsate to return the volume to 400 mL. Carcasses were shaken an additional 3 min for a total shaking duration of 4 min. A 10-mL aliquot was then collected from each carcass rinsate after shaking for a total of 4 min. During the last 2 replications, a 25-cm2 area of the breast skin was outlined with a template and marked with ink before any shaking. Preliminary trials showed that this ink would remain after 4 min of shaking both with and without sand added to the rinse. Cotton-tipped swabs were moistened with sterile PBS (~0.1 mL), and the marked area was uniformly swabbed using medium pressure with back-and-forth motions, twice horizontally and twice vertically. Swabs were then aseptically transferred to test tubes containing 10 mL of sterile PBS. The marked area on each carcass was swabbed again after the WCR to determine if rinsing with or without sand or shaking for 4 min affected bacteria recovery from the skin surface. The inclusion of the pre- and postswab samples in the last 2 replications was an attempt to quantify the impact of each carcass-rinsing method utilizing the same carcass, thereby attempting to account for individual carcass variability. All rin-sates were kept on ice until they were transported to the laboratory for bacterial enumeration.

Bacteriological Analysis
The collected rinsates from each WCR were analyzed for APC, coliforms, and E. coli. The PBS solutions containing the swabs were analyzed for APC only. Serial dilutions were prepared by transferring 1 mL from each rinsate and swab sample into 9-mL sterile dilution blanks containing 0.1% peptone. For APC analysis, 0.1 mL from each serial dilution was plated and spread in duplicate onto plate count agar. These plates were incubated at 35°C for 24 h before counting the resulting colony-forming units. The calculated minimal detection level for APC was 100 cfu/mL from the rinsates and 1,000 cfu/25 cm2 from the swabs. For coliform and E. coli analysis, 1 mL from each serial dilution was transferred and plated in duplicate onto Petrifilm E. coli-coliform plates [27]. The Petrifilm plates were incubated at 35°C for 24 to 48 h. Coliforms (red gas-producing colonies) and E. coli (blue gas-producing colonies) were counted and recorded. The minimal detection level of E. coli and coliforms was 1 cfu/mL.

Statistical Analysis
All bacterial counts were converted to log10 (cfu/mL of the rinsate or cfu/cm2) for statistical analysis. Data were analyzed in a factorial design using ANOVA with the GLM procedure [28] to test for differences in bacterial counts due to the treatment effects (peptone or peptone with sand), shaking duration (1 and 4 min), and their interaction. The GLM procedure was also used to test for differences in numbers of bacteria recovered from swab samples taken before and after WCR sampling.


   RESULTS AND DISCUSSION
TOP
 SUMMARY
 DESCRIPTION OF PROBLEM
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
CONCLUSIONS AND APPLICATIONS
 REFERENCES AND NOTES
 
Recovery means for APC, coliforms, and E. coli from peptone and peptone with sand rinsates are presented in Table 1Go. An ANOVA showed that the levels of APC, coliforms, and E. coli recovered from the peptone with sand rinsates were significantly higher (P < 0.05) than those recovered from the peptone-only rinsates by 0.6 log/mL of rinsate. In contrast, there were no significant differences (P > 0.05) in the level of recovery of these bacteria (≤0.2 log/mL of rinsate) from shaking durations of 1 and 4 min in either treatment (peptone and peptone with sand; Table 2Go). The treatment x shaking duration interaction term was also nonsignificant. Swabbing an area (25 cm2) of breast skin as an additional sampling method did not detect a difference between carcasses shaken in peptone and those shaken in peptone with added sand. The APC means recovered from prerinse swabs of carcasses shaken with peptone and peptone with sand were 4.1 and 4.0 log cfu/cm2, respectively. Aerobic plate count means among the 4-min postrinse swabs of carcasses shaken with peptone and peptone with sand were 3.6 log cfu/cm2. According to ANOVA, the APC means obtained from prerinse swabs are significantly greater than those of the postrinse swabs (≥0.4 log cfu/cm2). The lower recovery from swabs postrinse was attributed to the overall carcass rinsing effect and was not influenced by the addition of sand.


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  		Table 1. Mean log10 cfu/mL of rinsate of aerobic plate count (APC), coliforms, and Escherichia coli recovered from peptone and peptone plus sand whole-carcass rinses
 

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  		Table 2. Mean log10 cfu/mL of rinsate of aerobic plate count (APC), coliforms, and Escherichia coli recovered from shaking durations of 1 and 4 min1
 
The abrasive and scrubbing action of the sand during rinsing improved APC bacteria recovery by 0.6 log/mL of rinsate. These results support those of Fromm’s [20] and Cox et al. [24], suggesting that a scrubbing or abrading action may improve bacterial recovery from broiler carcasses. Bolton et al. [29] isolated Salmonella and Campylobacter from natural beach sand, showing that bacteria could be recovered that were associated with beach sand. It is possible that some of the bacteria loosened from the carcasses became associated with the sand, thereby lowering the overall recovery for the rinsate. The residual sand within the rinsate was not analyzed for bacteria in these experiments.

Research has shown that small populations of bacteria continue to be removed from the carcass after repeated rinses (up to 40 times), suggesting that bacteria are loosely attached to skin and can continuously be released into the rinsate of subsequent rinses [12]. This suggests that the addition of sand to the rinse may not alter the pattern of continuous release of bacteria from the carcass. Whether sand removes an additional small portion of attached bacteria or disrupts bacterial migration into and from the watery film, adding sand to the rinse increased overall APC, coliforms, and E. coli bacterial recovery by 0.6 log10 cfu/mL of rinsate.

Cox et al. [24] concluded that total plate count and Enterobacteriaceae recovery did not increase with increased number of shake times from 25 to 50 or 75 times. In addition to the findings of Cox et al. [24], Lillard [12] found that 10 separate 1-min WCR samplings of the same carcass recovered about the same amount of APC and Enterobacteriaceae, indicating that shaking or rinsing duration is not a significant factor in the level of bacterial recovery from rinsates. There was only 1 instance in which APC recovery was significantly reduced (by 0.4 log10 cfu/mL of rinsate) in 2 consecutive rinses. Lillard concluded that the number of bacteria recovered remained about the same from the first to the tenth rinse. Comparatively, Lillard’s research showed that there was no difference between the first 1-min rinse and the tenth 1-min rinse. Results of the present experiment agree with those of Cox et al. [24] and Lillard [12], in which carcasses shaken for 1 or 4 min, with or without sand, did not differ in the recovery of APC, coliforms, and E. coli per milliliter of rinsate.

The APC levels recovered from carcass swabs for both treatment (peptone and peptone with sand) were the same before and after rinsing. Adding sand to the rinse was apparently more effective in recovering higher levels of bacteria from the carcass rinsate; therefore, swabs of carcass skin from carcasses shaken with sand should have yielded lower APC, but these results did not occur or were below the level of detection (1,000 cfu/25 cm2). When comparing the WCR method to the swabbing method, Gill and Badoni [5] concluded that there was not a significant correlation between bacterial levels recovered between the 2 methods. Swabbing a relatively small area of the breast skin (25 cm2), when compared with rinsing the entire carcass (internal and external surface area), therefore may not be a reliable comparison. Previous studies have found that bacterial recovery from broiler carcasses differs for the front and back of the carcass, differs internally and externally, and differs by the carcass part sampled [6, 21, 30]. Previous sampling of skin-on breast parts showed that rinsing recovered higher levels for APC (3.70 log10 cfu/cm2) than swabbing the entire breast skin surface (2.36 log10 cfu/cm2) [6]. This direct comparison was a strong advocate for rinsing versus swabbing for breast skin; however, the higher APC recovery from the rinsate (1.3 log cfu/cm2) represents the entire skin-on breast sample (skin and meat) not just the external skin surface.

The specific mechanisms by which sand removes bacteria from the carcass are not known, and require further investigation. Incorporating sand into carcass or part rinses is a destructive method, and even if greater bacterial recovery had been obtained, sand would not be suggested for common commercial use for carcass bacterial decontamination. However, the results of this research demonstrated that adding sand to rinses recovered greater numbers of APC, coliforms, and E. coli bacteria from broiler carcasses. Therefore, the objective of future research should evaluate the ability of sand to improve the detection of carcass bacteria that are present in low levels (salmonellae) and are detected by incidence following sample enrichment. The incorporation of sand into carcasses rinses may improve the incidence of salmonellae detection from carcasses with salmonellae levels near the limit of detection by rinsate enrichment, 13 cfu/carcass [18].


   CONCLUSIONS AND APPLICATIONS
TOP
 SUMMARY
 DESCRIPTION OF PROBLEM
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 CONCLUSIONS AND APPLICATIONS
REFERENCES AND NOTES
 

  1. The inclusion of sand into the rinse for the WCR procedure improved APC recovery by 0.6 log cfu/mL of rinsate, coliform recovery by 0.7 log cfu/mL of rinsate, and E. coli recovery by 0.6 log cfu/mL of rinsate.
  2. Increased carcass shaking duration from 1 to 4 min had no significant benefit on the level of bacteria recovered.
  3. Additional studies need to be conducted to reveal the mechanisms by which sand enables the recovery of higher levels of bacteria from carcass rinsates.


   ACKNOWLEDGMENTS
 
We are grateful for the assistance provided by Jerrie R. Barnett, Dianna V. Bourassa, Jeromey S. Jackson, and L. Nicole Bartenfeld of the USDA-ARS Richard B. Russell Research Center and Arthur B. Karnuah of the University of Georgia for sample collection.


   FOOTNOTES
 
1 Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the USDA. Back

2 Current address: University of Connecticut, 3636 Horse Barn Road Ext., Storrs, 06269-4040. Back


   REFERENCES AND NOTES
TOP
 SUMMARY
 DESCRIPTION OF PROBLEM
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 CONCLUSIONS AND APPLICATIONS
 REFERENCES AND NOTES
 

  1. Kotula, K. L., and Y. Pandya. 1995. Bacterial contamination of broiler chickens before scalding. J. Food Prot. 58:1326–1329.[Web of Science]
  2. Capita, R., M. Prieto, and C. Alonsi-Calleja. 2004. Sampling methods for microbiological analysis of red meat and poultry carcasses. J. Food Prot. 67:1303–1308.[Web of Science][Medline]
  3. Kraft, A. A. 1971. Microbiology of poultry products. J. Milk Food Technol. 34:23–29.
  4. Cox, N. A., and J. S. Bailey. 1987. Pathogens associated with processed poultry. Pages 293–316 in The Microbiology of Poultry Meat Products. F. E. Cunningham and N. A. Cox, ed. Acad, Press Inc., Orlando, FL.
  5. Gill, C. O., and M. Badoni. 2005. Recovery of bacteria from poultry carcasses by rinsing, swabbing, or excision of skin. Food Microbiol. 22:101–107.[CrossRef][Web of Science]
  6. Gill, C. O., M. Badoni, L. F. Moza, S. Barbut, and M. W. Griffiths. 2005. Microbiological sampling of poultry carcass portion by excision, rinsing, or swabbing. J. Food Prot. 68:2718–2720.[Web of Science][Medline]
  7. Izat, A. L., M. Colberg, M. H. Adams, M. A. Reiber, and P. W. Waldroup. 1989. Production and processing studies to reduce the incidence of salmonellae on commercial broilers. J. Food Prot. 52:670–673.[Web of Science]
  8. Thomas, C. J., and T. A. McMeekin. 1981. Attachment of Salmonella spp. to chicken muscle surfaces. Appl. Environ. Microbiol. 42:130–134.[Abstract/Free Full Text]
  9. Piette, J. P. G., and E. S. Idziak. 1989. New method to study bacterial adhesion to meat. Appl. Environ. Microbiol. 55:1531–1536.[Abstract/Free Full Text]
  10. Notermans, S., and E. H. Kampelmacher. 1974. Attachment of some bacterial strains to the skin of broiler chickens. Br. Poult. Sci. 15:573–585.[Web of Science][Medline]
  11. Lillard, H. S. 1985. Bacterial cell characteristics and conditions influencing their adhesion to poultry skin. J. Food Prot. 48:803–807.[Web of Science]
  12. Lillard, H. S. 1988. Comparison of sampling methods and implications for bacterial decontamination of poultry carcasses by rinsing. J. Food Prot. 51:405–408.[Web of Science]
  13. Selgas, D., M. L. Marin, C. Pin, and C. Casas. 1993. Attachment of bacteria to meat surfaces: A review. Meat Sci. 34:265–273.[CrossRef]
  14. Thomas, C. J., and T. A. McMeekin. 1982. Effect of water immersion on the microtopography of the skin of chicken carcasses. J. Sci. Food Agric. 33:549–554.[CrossRef][Web of Science]
  15. Thomas, C. J., and T. A. McMeekin. 1984. Effect of water uptake by poultry tissues on contamination by bacteria during immersion in bacterial suspensions. J. Food Prot. 47:398–402.[Web of Science]
  16. Kim, K. Y., J. F. Frank, and S. E. Craven. 1996. Three-dimensional visualization of Salmonella attachment of poultry skin using confocal scanning laser microscopy. Lett. Appl. Microbiol. 22:280–282.[Web of Science][Medline]
  17. Buhr, R. J., M. E. Berrang, and J. A. Cason. 2003. Bacterial recovery from breast skin of genetically feathered and featherless broiler carcasses immediately following scalding and picking. Poult. Sci. 82:1641–1647.[Abstract/Free Full Text]
  18. Buhr, R. J., D. V. Bourassa, J. K. Northcutt, A. Hinton Jr., K. D. Ingram, and J. A. Cason. 2005. Bacteria recovery from genetically feathered and featherless broiler carcasses after immersion chilling. Poult. Sci. 84:1499–1504.[Abstract/Free Full Text]
  19. Cason, J. A., A. Hinton Jr., and R. J. Buhr. 2004. Impact of feathers and feather follicles on broiler carcass bacteria. Poult. Sci. 83:1452–1455.[Abstract/Free Full Text]
  20. Fromm, D. 1959. An evaluation of techniques commonly used to quantitatively determine the bacterial population on chicken carcasses. Poult. Sci. 38:887–893.[Web of Science]
  21. Patterson, J. T., and D. J. Stewart. 1962. Bacteriology of processed broilers. I. Methods of examination. Rec. Exp. Min. Agric. N. Irel. 11:57–63.
  22. Patterson, J. T. 1972. Microbiological sampling of poultry carcasses. J. Appl. Bacteriol. 35:569–575.[CrossRef][Medline]
  23. Fletcher, D. L., D. M. Thomason, J. O. Reagan, and D. D. Smith. 1982. Influence of oily bird syndrome on the shelf-life of fresh ice-packed broilers. J. Food Prot. 45:813–815.[Web of Science]
  24. Cox, N. A., A. J. Mercuri, J. E. Thomson, and V. Chew. 1976. Swab and excised tissue sampling for total and Enterobacteriaceae counts of fresh and surface frozen broiler skin. Poult. Sci. 55:2405–2408.[Web of Science][Medline]
  25. Becton-Dickinson and Co., Sparks, MD.
  26. Dickens, J. A., N. A. Cox, J. S. Bailey, and J. E. Thomson. 1985. Automated microbiological sampling of broiler carcasses. Poult. Sci. 64:1116–1120.[Web of Science]
  27. 3M Health Care, St. Paul, MN.
  28. SAS Institute. 1999. SAS/STAT for Personal Computers Version 8.1. SAS Inst. Inc., Cary, NC.
  29. Bolton, F. J., S. B. Surman, K. Martin, D. R. A. Wareing, and T. J. Humphrey. 1999. Presence of Campylobacter and Salmonella in sand from bathing beaches. Epidemiol. Infect. 122:7–13.[CrossRef][Medline]
  30. Lillard, H. S. 1991. Microbiological comparison of inner and outer surfaces of commercially processed broilers and the adhesion of bacteria to these tissues. Biofouling 5:65–73.



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