Evaluation of Microbial Contamination of Chicken Carcasses During Processing

Introduction
Poultry meat can be easily contaminated with microorganisms, due to many factors, as nutrients, high water activity and neutral pH. These characteristics are favorable to the development of microorganisms, which are intrinsic to poultry or microorganisms that come from external sources during the processing. So, the
implementation of HACCP (Hazard Analysis and Critical Control Points) in poultry industry is extremely important, because it involves the constant monitoring of all steps of the process, aiming the food safety of final product. Industries must implement this food safety program to serve both internal and external market (JIMÉNEZ and others 2002; MEAD 2004; GALHARDO and others 2006).

Microbiological criteria establish the acceptability of a product based on presence or absence of microorganisms, quantity of toxins per mass unit, volume, area or batch. The microorganisms included in a criterion must be relevant, as pathogens, indicators, or spoilers (FOOD AND AGRICULTURE ORGANIZATION (FAO) 1997; COMISSION REGULATION (CE) n° 2073/2005).
The microbiological quality of chicken meat can be determined by its sanitary conditions, contamination during processing, storage conditions, transportation and commercialization. However, contamination occurs easily in the first stage of slaughtering (GALHARDO and others 2006).
Before evisceration process, carcasses must be washed in shower with pressured water, since the whole carcass must be washed including feet. After the washing, chicken are submitted to evisceration, which can be automated or not. In this step, viscera tearing and the direct contact with contaminated surfaces must be avoided. The automated stage involves cloacae extraction, abdomen cutting, and evisceration. After this stage, sanitary inspection occurs and viscera are manually removed, and the edible giblets (heart, liver and gizzard) are separated to be chilled. Windpipe and crop are removed mechanically, and carcasses are finally washed both external and internally, before passing through the pre-chilling system (BRASIL 1998).
Pre-chilling process decreases carcass temperature after the process of evisceration and washing. This system has stainless steel tanks with cold water added with ice cubes (both are chlorinated at 1ppm maximum), where chickens are immersed. They are called pre-chiller and chiller. These tanks have a continuous carrier thread, while water and ice are being renewed every time, and its flow is against chicken carcass flow. At pre-chiller system, the temperature of water cannot be over 16°C; at chiller tank, the temperature must be at 4°C maximum, and chickens must be until 7°C in the end of this process. These parameters contribute to the reduction of any microorganisms that could be found in the poultries (BRASIL 1997; BRASIL 1998).
The evisceration process can cause tearing of intestine, gall bladder or crop, contaminating chicken surface with their contents. Affected chicken carcasses are reprocessed, or in extreme cases, condemned, but the reprocessing or the condemnation delays the operation of the processing plant and increases the cost of producing a quality product (NORTHCUTT and others 1997).
When visible contamination occurs, skin with fecal, gastric or bile waste is trimmed. After it, knives must be washed in potable water and immerse in hot water in order to disinfect the blade. This procedure aims the use of carcasses for cutting and processing. However, if the knife is not appropriately washed, removing skin can contaminate the meat, and some microorganisms could be transferred from contaminated skin to meat. Also skinless carcasses pass through the showers and washing machine, aiming to be clean internal and externally before be chilled (NORTHCUTT and others 1997; BRASIL 1998).
According to Food Safety and Inspection Service (FSIS), since 1978 the food industries can proceed the non-contamination by many methods, and washing is allowed for chickens as an alternative to knife trimming. Studies have presented that the first method is equally effective in removing fecal contamination (FOOD SAFETY AND INSPECTION SERVICE 1997).
The aim of this report is to contrast the decreasing of the number of microorganisms of chicken carcasses that were washed after a gastric or fecal contamination with those that were trimmed, in order to evaluate the efficiency of methods for removing contamination. The experiments also aim to evaluate the efficiency of pre-chilling immersion process in the reduction of microorganisms in chicken carcasses.


Materials and Methods
Sampling Criteria
The sampling was done in a company that slaughters male and female birds with approximately 47 days. All chickens were withdrawn from feed at least six hours before slaughter, and stunned through the conduction of electric energy in a tank with water, making the bleeding easier. After bleeding process, they were scalded, in order to remove the feathers. So, they were conducted to evisceration line.
Carcass sampling was done in two stages of the process, that is, immediately after evisceration, and after pre-chilling. All chicken collected presented fecal or gastric contamination before washing. It was collected 158 samples, which five carcasses were taken out after evisceration, and trimming was not done, neither was the washing, in order to evaluate the amount of microorganisms in these samples. Thirty three carcasses were collected after skin removal, not washed; thirty samples were collected after skin removal and washed; and thirty were just washed and collected in the end of the process contrasting with the skinless chicken.
Two types of samples were collected after pre-chilling system, that is, thirty chickens only washed and thirty skinless and washed chicken carcasses, in order to compare the quantity of microorganisms present in the samples. With the results, it was possible to evaluate not only the efficiency of these methods to reduce the contamination, but also the efficiency of immersion chilling system. Samples were put in plastic bags and were individually immersed in a buffer solution (peptone water). Then, they were vigorously mixed into buffer in order to cover the sample completely in this peptone water (external and internally). The resulting bath (buffer and chicken water) was transferred to plastic bags kept in temperature of maximum 4°C.
Microbiological Analyses
Carcasses were submitted to counting standard in plates of mesophilic aerobic microorganisms, total coliforms, Escherichia coli and Staphylococcus aureus, in according to Brazilian regulations. Aerobic Count (AC), Escherichia coli/Coliform Count (EC) and Staph Express Count (STX) PETRIFILM PLATESTM (Minnesota, USA) were used to determine mesophilics aerobics, coliforms and Staphilococcus aureus, and the results were expressed in CFU/g (BRASIL 2003; BRASIL 2005).

Sampling was done in a Brazilian chicken exporter company having some microbiological criteria as internal standard, as shown in table 1.

Table 1: Microbiological criteria used as indicators of quality assurance.
Slaughterhouse Standards "SS" (CFU/g)* - European Standards "ES" (CFU/g)**

Mesophilics aerobics: "SS": 1.00x100000 - "ES": 5.0x1000000
Total coliforms: "SS": 1.00x10000 - "ES": Not available
E. coli "SS": 1.00x100 - "ES": 5.0x100
S. aureus "SS": 1.00x1000 - "ES": Not available

*No standard in Brazilian regulations.
**Comission Regulation (EC) n° 2073/2005


Results and Discussion

The results of all analyses can be observed in the table 2.

Table 2: Average results of microbiological analyses of chicken carcasses.


Method for removing contamination: - Group I: Before chiller -
AI: No trimming and no washing - Mesophilics aerobics (CFU/g): 1.12x100000 - Total coliforms (CFU/g): 1.09x1000 - E.Coli (CFU/g): 5.80x100 - S.aureus (CFU/g):1.42x10
BI: Trimming and no washing - Mesophilics aerobics (CFU/g): 1.40x100000 - Total coliforms (CFU/g): 1.49x1000 - E.Coli (CFU/g): 6.59x100 - S.aureus (CFU/g):2.76x10
CI: Trimming and washing - Mesophilics aerobics (CFU/g): 1.44x100000 - Total coliforms (CFU/g): 2.06x1000 - E.Coli (CFU/g): 7.77x100 - S.aureus (CFU/g):1.70x10 -
DI: No trimming and with washing - Mesophilics aerobics (CFU/g): 2.76x100000 - Total coliforms (CFU/g): 2.36x1000 - E.Coli (CFU/g): 1.01x1000 - S.aureus (CFU/g):1.35x10 -

Method for removing contamination: - Group II: After chiller -
CII: With trimming and washing - Mesophilics aerobics (CFU/g):1.96x1000 - Total coliforms (CFU/g): 3.79x10 - E.Coli (CFU/g): 2.19x10 - S.aureus (CFU/g): 9.93x1 -
DII: No trimming and with washing - Mesophilics aerobics (CFU/g): 2.57x1000 - Total coliforms (CFU/g): 5.18x10 - E.Coli (CFU/g): 3.53x10 - S.aureus (CFU/g): 9.19x1 -

In the group I: before chiller, the number of microorganisms is stable for all samples; therefore, contamination is not reduced neither with trimming, nor washing. The final washing of carcasses (external and internally) is done quickly in the process, so probably there is no time enough to reduce the counting of microorganisms. Comparing the samples of group II: after chiller, it can be observed that there are no significant differences between the results of groups CII and DII, so the trimming seems not necessary, since all values are within the limits of table 1.
Contrasting groups I and II in relation to the efficiency of pre-chilling to reduce the level of microorganisms, the results evidence a decreasing in all parameters at group II, showing the importance of immersion system due to the renewable cold water circulating in the process. There was a significant reduction of mesophilic aerobic microorganisms after the chiller tank, showing that the low temperature of water minimizes the presence of bacteria in chicken carcasses. The majority of bacteria that can be found in chicken is the mesophilic aerobic, however just a small amount develop in temperatures less than 7°C (CARVALHO and others 2005).
Considering the others microbiological criteria, the significant counting reduction is also evidenced, indicating that the cold circulating water helps this process. The level of total coliforms is used to evaluate the hygienic conditions of the process, because coliform group is present in the homeothermic animal intestine (FRANCHIN and others 2007). E.coli is an indicator of fecal contamination (COMISSION REGULATION (EC) n° 2073/2005). There is not a standard established to S. aureus, but this microorganism is an excellent indicator of Good Manufacturing Practices, because its presence is related to the hygiene of works.
All samples collected before pre-chilling system (group I) are not in according to the standards of the slaughterhouse for mesophilic aerobic microorganisms and E. coli (table 1). Observing the European regulation, group I samples are not agreeing with E. coli standard, but they are in the interval for mesophilic aerobic bacteria.
On the other hand, the analysis results of all chickens collected after chiller (group II) were within limits (in according to table 1) for all microorganisms, as for the skinless chicken as the carcasses washed. It demonstrates that the type of method for removing contamination (trimming and/or washing) results in a product available for the consumption. The pre-chilling system in tanks is efficient, due to the constant renewal of water and ice since carcasses have presented a reduction in the number of microbes below the acceptable level (table 1).
This paper evidences that the results of samples collected after chiller were satisfactory, being not in according to GALHARDO and others (2006), because their results showed that carcasses had higher limits. Actually, the most of authors consider that pre-chilling tanks are not efficient in decontamination of carcasses and they have observed the lower water flow in those tanks being the determinant factor of inefficiency of the decontamination process.
Otherwise, FRANCHIN and others (2007) report that the trimming procedure is not the unique adequate; washing is equally satisfactory. BLANCK and POWEL (1995) relate the using of pre-chilling tanks as an alternative to decontamination of carcasses. The immersion system can minimize the quantity of microorganisms as long as there is continuous water flow, and adequate temperature monitoring. THOMSON and others (1975) state that immersion tanks can reduce bacteria contamination in carcasses, if they are used appropriately, and with adequate water renewal.

Conclusion
Both methods (trimming and washing) for reducing contamination can be applied, aiming the use of chicken for cutting and processing. So, immersion pre-chilling system is the determinant to the decreasing of number of microorganisms, as long as it is following all legislation requirements. If the chicken carcass is only washed (without the trimming) it can be commercialized intact with quality assurance. Economically, to keep the carcasses with skin is more interesting for the company.





References

1. BLANCK, G. POWELL, C. 1995. Microbiological and hydraulic evaluation of immersion chilling for poultry. Journal of Food Protection 58(12):1386-1388.

2. BRASIL, Ministério da Agricultura, Pecuária e Abastecimento. 1997. Regulamento da Inspeção Industrial e Sanitária de Produtos de Origem Animal (RIISPOA). Título IV. Registro e relacionamento de estabelecimentos. Capítulo I, artigo 62.

3. BRASIL, Ministério da Agricultura, Pecuária e Abastecimento. Portaria n° 210, de 10 de Novembro de 1998. Regulamento Técnico da Inspeção Tecnológica e Higiênico Sanitária de Carne de Aves.

4. BRASIL, Ministério da Agricultura, Pecuária e Abastecimento. Instrução Normativa 62, de 26 de Agosto de 2003.

5. BRASIL, Ministério da Agricultura, Pecuária e Abastecimento. Instrução Normativa 40, de 12 de Dezembro de 2005.

6. CARVALHO, A.C.F.B.; CORTEZ, A.L.L.; SALOTTI, B.M. and others. 2005. Presença de microrganismos mesófilos, psicrotóficos e coliformes em diferentes amostras de produtos avícolas. Arquivos do Instituto Biológico 72 (3): 303-307.

7. COMISSION REGULATION (EC) n° 2073/2005 of 15 November 2005 on microbiological criteria for foodstuffs. Official Journal of European Union.

8. FOOD AND AGRICULTURE ORGANIZATION (FAO). 1997. Codex Alimentarius. Principles for the Establishment and Application of Microbiological Criteria for Foods. CAC/GL 21.

9. FOOD SAFETY AND INSPECTION SERVICE (1997). FSIS Clarifies and Strengthens Enforcement of Zero Tolerance Standard for Visible Fecal Contamination of Poultry. Publication on line, available in:

10. FRANCHIN, P. R.; STEINMULLER, A.; DEGENHARDT, R. and others. 2007. Eficiência da lavagem de carcaças de frango com contaminação fecal aparente, comparada ao corte das áreas afetadas, para redução de contagem bacteriana. Higiene Alimentar 21(152): 106-110.

11. GALHARDO, J.A.; LOPES, M.; OLIVEIRA J.T. and others. 2006. Eficácia dos tanques de pré-resfriamento na redução de contaminação bacteriana em carcaças de frango. Ciências Agrárias 27(4): 647-656.

12. JIMÉNEZ, S.M.; SALSI, M.S.; TIBURZI M.C. and others. 2002. A comparison between broiler chicken carcasses with and without visible fecal contamination during the slaughtering process on hazard identification of salmonella spp. Journal of Applied Microbiology: 593-598.

13. MEAD, G.C. Microbiological quality of poultry meat: a review. 2004. Brazilian Journal of Poultry Science 6(3): 135-142.

14. NORTHCUTT, J.K.; SAVAGE, S.I.; VEST, L.R. 1997. Relationship between feed withdrawal and viscera condition of broilers. Poultry Science 76: 410-414.

15. THOMSON, J.E.; COX, N.A.; WHITEHEAD, W.K. and others. 1975. Bacterial counts and weight changes of broiler carcasses chilled commercially by water immersion and air-blast. Poultry Science 54:1452-1460.

Authors: Valéria Castro Cardoso Guerra and Cleber Rabelo da Roza

*Valeria Castro Cardoso Guerra

**Cleber Rabelo da Roza

*Hygiene and Food Processing UERGS/UCS Rua Francisco Getulio Vargas, 1130 Bairro Petropolis CEP 95070-560 Caxias do Sul Brasil e-mail: [e-mail]

** The University of Queensland School of Land, Crop and Food Sciences St Lucia Campus QLD 4072 - Australia - e-mail: [e-mail]

Previous address(es): **State University of Rio Grande do Sul Avenida Julio de Castilhos, 3947 Bairro Cinquentenario CEP 95010-005 Caxias do Sul Brasil email: [e-mail]