EFFECT OF RADIATION, HYDROGEN PEROXIDE AND CHLORINE ON BACTERIAL DECONTAMINATION OF BROILER CARCASSES

EFFECT OF RADIATION, HYDROGEN PEROXIDE AND CHLORINE ON BACTERIAL DECONTAMINATION OF BROILER CARCASSES

H.F.A. EL-DOSOKY and SHERIN S. MOSTAFA

Animal Health Research Institute, Mansoura Lab., Mansoura, Egypt.

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                                             ABSTRACT

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Key words: Broiler, irradiation, Staph.aureus, hydrogen peroxide.

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INTRODUCTION

Poultry meat is a nutritious food consumed all over the world because of its relatively low cost and low fat content, however it is highly perishable with a relatively short shelflife even where it is kept under refrigeration. Although poultry constitute an excellent source of high quality and easily digested protein it is liable to transmit different types of potentials to consumers Zahra, (2001).Many attempts were applied to reduce the microbial findings and level of poultry meat contamination through using variable chemicals like sodium hypochlorite which resulted in significant reduction in the number of microorganisms, Ismail et al. (2001).One of the newly emerging technologies to ensure microbiological safety of meat is radiation processing Kanatt et al. (2005).The safety and efficacy of irradiation in food preservation has been thoroughly demonstrated world wide Pelezar et al. (1997). The radiation doses required to inactivate 90% of the common foodborne pathogens associated with meat and poultry are in the range of 1-4KGy,Thayer et al. (1993). Contamination of poultry carcasses with Staph. aureus usually occurs through handling by human, if such products are left without refrigeration for several hours or cooled slowly in refrigerator, growth of Staph.aureus and enterotoxin formation may occur, growth of Staph.aureus in the product is favoured by lack of competitive bacteria which are destroyed by heat,Bryan (1980). The aerobic plate counts (APCs), Most Probable Number of Coliforms (MPN) and counts of Staph.aureus in chicken carcasses collected from different poultry shop were 3.38x10⁶±1.02x10⁶, 2.58x10⁴±0.9x10⁴ and 9.95x10³± 1.56x10³cfu/gm respectively, Morshdy et al. (2008).While the counts were 6.1±0.1,2.7±0.1 and 3.7±0.1 log₁₀ cfu/gm respectively in fresh whole chicken broiler carcasses, Mira; Eskandar, (2007) also Mahmoud; Hammouda (2006) examined thigh and breast and found that APCs and Staph.aureus count were 1.4x10⁶±4x10⁵ and 6x10⁵±2x10⁴ while Staph.aureus count were 8.9x10³±0.3x10³ and 2.7x10³±1.7x10⁴ respectively.May (1974) mentioned that final rinsing of commercially slaughterd broilers with 25 ppm chlorine resulted in significant reduction in TVCs.,Whyte et al. (2001) proved that final rinsing of poultry carcasses with 25ppm chlorine reduce TVCs from 4.98±0.38 to4.52±0.24 and Enterobacteriaceae from 3.37±0.31 to 3.16±0.16 log₁₀cfu/gm. Commercial chlorine chiller on poultry carcasses during processing reduce APCs, Staph.aureus from 6.2x10⁴ and 1.4x10⁴ to 2.4x10⁴ and 6x10³cfu/gm respectively Gelis; Kabul (2006), while Karen et al. (2010)mentioned that significant reduction in APCs and Coliforms by 50 ppm chlorine rinsing for three minutes the reduction were 0.4 and 0.21 log₁₀ cfu/gm respectively. Hydrogen peroxide is highly unstable and breaksdown into water and single oxygen molecule which is strong oxidizing and disinfecting agent Black et al. (2008),also several investigators concluded that chlorine and hydrogen peroxide were most frequently used in commercial poultry processing as antimicrobials due to their availability, low cost and efficacy Bolder, (1997); Hugas; Tsigarida (2008); Northcutt; Jone (2004), also Mostafa (2010) concluded that Hydrogen peroxide 0.1% in chiller reduce APCs, Coliforms and Staph.aureus counts by 97.3%,72.01% and 94.9 % respectively and similar results were recorded by EL-said et al. (2002). Oliveira et al. (2009) mentioned that gamma radiation 1.5 and 3KGy on chicken breast reduce APCs from 3.0±0.01 to less than 1.0 and total Coliforms reduced from 2.9±0.3 to 0.3±0.4 and Staphaureus to less than 0.5 log₁₀ cfu/gm respectively. Also Min et al. (2007) reported that no viable cells were detected after exposure of inoculated chicken thigh and breast to 2KGy radiation. Irradiation with air and vacuum reduce mesophiles from 4 and 3.8 to 3.3 and 2.7 log₁₀cfu /gm at 2KGy and 1.7 and 1.6 log₁₀ cfu/gm at 3KGy while Coliforms reduced from 2.2 and 3 log₁₀ cfu/gm to 0.6 and 0.5 log₁₀ cfu/gm by 2KGy and not detected at 3KGy respectively Mantilla et al. (2011).The results recorded by Mohamed et al. (2008)on fish fillets exposed to radiation on APCs, Coliforms and Staph.aureus were in control samples 6.4,2.68 and 2.38log₁₀ cfu/gm while at 2KGy were 2.6, less than 3 and less than 2log₁₀ cfu/gm and at 3KGy were 2.1, less than 3 and less than 2 log₁₀ cfu/gm respectively.                        

Therefore this study focused on the effect of Chlorine, Hydrogen peroxide and Irradiation on bacterial population, Coliforms and Staph.aureus in whole chicken carcasses from a local poultry plant with comparison between the three methods.

MATERIALS and METHODS

Total number of 80 broiler chicken carcasses from an automatic poultry slaughtering plant in Dakahlia, Egypt were collected after complete preparation (slaughtering, scalding, defeathering and evisceration), just afterwashing in the chiller where they divided into four groups. The first group [control group] were placed in a chiller containing cold water for 60  minutes and left as a control.

The second group were divided into two subgroup (each one ten carcasses) one of them rinsed with 25ppm chlorine (sodium hypochlorite 14% vol./vol.) and the other one rinsed with 50 ppm chlorine for three minutes then sampling.

The third group were also divided into two subgroup (each oneten carcasses) one of them rinsed with 1% hydrogen peroxide and the other one rinsed with 2% hydrogen peroxide for two minutes.

The fourth group divided into two subgroups (each one ten carcasses), 250 gm from each carcass were packed in a sterile polyethylene bags heat sealed then irradiated at National Center for Radiation Research and Technology (NCRRT) Nasr City, Cairo. The irradiation source was Cobalt 60 irradiation model ISS LEDDVATED. The dose rate was established using alanine transfer dosimeter and variation in the absorption of irradiation dose was minimized by placing the samples within a uniform area of the irradiation field. One subgroup exposed to 2KGy and the other subgroup exposed to 3KGy of gamma rays. After irradiation 25gm of each exposed samples were homogenized with 225ml of 0.1% peptone water in a stomacher for 2.5 minutes at 3000rpm followed by ten fold serial dilution in 0.1% peptone water Each of the prepared samples were examined for enumeration of its microorganisms content as follows.

1-Total Colony Count:

0.1 ml of each dilution was evenly spread over the dry surface of standard plate count agar using a sterile bent glass spreader only plates contain 30-300 colonies were counted as the total colony per gram of samples according to APHA (1985).

2-Coliform Count:

 Using most probable number technique (MPN) according toICMSF (1978).

3- Staph. Aureuscount:

Using Baired Parker agar medium with eggyolk tellurite emulsion APHA (1992).

Biochemical Identification of Staph.aureus;

Identification of Staph.aureus according to APHA (1992);films were prepared from the pure culture of isolated organisms stained with Gram's stain and examined microscopically for G+ve cocci.

The tests for identification were motility, catalase test, mannitol test and coagulase test (tube method).

RESULTS

Table 1: Statistical analytical results for effect of chlorine on decontamination process.

APC=aerobic plate count & MPN=most probable number of coliforms & Staph.aureus=staphylococcus aureus count, NG=no growth.

• Means results of decontamination are significantly different (P<0.05)

Table 2: Statistical analytical results for effect of hydrogen peroxide on decontamination process.

Table 3: Statistical analytical results for effect of gamma rays irradiation on decontamination process.

DISCUSSION

The sanitary evaluation of slaughtered birds is based mainly on its microbial findings and level of contamination. Many investigators proved that more than 70 % of poultry carcasses are contaminated and the microbial count being more than 3x10⁵cfu/ml, Tamblyn et al. (1997).

Table (1) shows that the mean log₁₀cfu/gmvalues of APCs in examined control samples, after decontamination with 25ppm and 50ppm chlorine were 5.73 ±3.23,5.71±3.08 and 5.62±3.57 log₁₀cfu/gm. while MPN count were 3.74±1.45, 3.69±1.07 and 3.55±1.44log₁₀cfu/gm and the counts of Staph.aureus were 3.62±1.59,3.58±1.17 and 3.6±1.1 log₁₀cfu/gm respectively, the results in control samples nearly in accordance with Bryan (1980),Tamblyn et al. (1997); Mahmoud, Hammouda (2006); Mira, Eskandar (2007) and Morsh-dy et al. (2008).The higher microbial load could be attributed to the technique of evisceration and poor hygienic levels. The reduction were more than those reported by Whyte et al. (2001) and similar toGelis, Kabul (2006); Stopforth et al. (2007) and Karen et al. (2010)the difference in reduction may be due to the final processing and rinsing before decontamination process. The results were reduced significantly when compared statistically with corresponding controls (P<0.05).

Table (2): The results of decontamination with hydrogen peroxide (H₂O₂) declared that. The mean log cfu value of APCs were 5.73±`3.23,5.34±2, and 5.20±2.47 log₁₀ cfu/gm after decontamination with hydrogen peroxide 1% and 2% respectively while MPN count were 3.74±1.45,3.53±1.46 and 3.30±1.04 log₁₀cfu/gm and the counts of Staph.aureus were 3.62±1.59,3.44±1 and 3.30±1.07 log₁₀cfu/gm respectively similarly with those recorded by Bolder (1997); Northcutt, Jones (2004); Black et al. (2008) and Hugas; Tsigarida (2008),higher results recorded by EL-Said et al. (2002) and Mostafa (2010),while the reduction after 2%H₂O₂ were similar to Northcutt, Jones (2004)and lower than the results recorded by Mostafa (2010). The results were reduced significantly when compared with corresponding controls (P<0.05).

The results in Table (3)declared that the mean log cfu value of APCs were 5.73±3.23,4.92±2.11 and 4.80±0.1 log₁₀cfu/gm in examined control samples, after irradiation with 2KGy and 3KGy respectively while MPN count were 3.74±1.45,2.87±0.1 log ₁₀cfu/gm respectively in control samples and after irradiation with 2KGy and no growth after irradiation with 3KGy and the counts of Staph.aureus were 3.62 ±1.59 and 2.93±0.05 log₁₀cfu/gm respectively in examined control samples and after irradiation with 2KGy and no growth after irradiation with 3KGy the reduction after irradiation nearly similar to Mohamed et al. (2008); Oliveira et al. (2009) and Mantilla et al. (2011), while higher reduction recorded by Min et al. (2007) the reduction after irradiation in APC in addition to no growth of Coliforms and Staph.aureus were similarly to Mohamed et al. (2008); Oliveira et al. (2009) and Mantilla et al. (2011). The effects of irradiation as log viable counts of all the inspected bacteria showed gradual reduction as the irradiation dose increased. The results were reduced significantly when compared with corresponding controls (P<0.05).

In conclusion from the aforementioned results declared that chlorine is a bactericidal, viricidal and fungicidal agent can be successfully applied in the food industry and may conistitute an important factor in reducing losses resulting from food spoilage and human infection.

The use of hydrogen peroxide in chiller used for chicken chilling prior to its packaging greatly reduce its bacterial load. It is a power full sanitizer for poultry carcasses, it enhances its meat quality.

Radiation did not affect the sensory character of chicken carcasses and produces no apparent changes in the organoleptic characteristics, it inhibit microbial growth and so extends the shelf life of the product. From the results it was obvious that the microbial reduction was greater after radiation than after hydrogen peroxide and after hydrogen peroxide than after chlorine.

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