Effects of Acetic Acid and Hydrogen Peroxide on the Microbiological Quality and Skin Appearance of Poultry Carcasses

The microbiological quality and skin appearance of poultry carcasses were determined after acetic acid and hydrogen peroxide spray. Acetic acid at 1% concentrations showed a significant effect(P<0.05)in reducing total mesophilic bacteria count, total coli form count, Escherichia coli count and Staphylococcus aureus count when compared with a sample without treatment,10.50x10 3 ,1.03x10 3 ,7.5x10 1 ,1.05 x10 2 and 27.47x10 3 , 2.71x10 3 , 4.41x10 2 , 2.74x10 2 cfu/cm 2 respectively. No differences were observed in skin appearance due to 1% acetic acid treatment. Hydrogen perioxide at 1% concentrations did not significantly(P>0.05) effect the microbial load when compared with asample without treatment,26.33x10 3 , 2.61x10 3 ,3.70x10 2 ,2.63x10 2 and 27.47x10 3 ,2.71x10 3 ,4.41x10 2 ,2.74x10 2 cfu/cm 2 respectively. The skin of carcasses treated with H2O2 ,was bleached and bloated. INTRODUCTION Carcasses are contaminated with various spoilage and pathogenic microorganisms at many stages of poultry processing, even though good manufacturing practices are observed during slaughtering[1]. Since the microorganisms are firmly attached on poultry skin and are localized in the capillary spaces, they are not easily rinsed off and are not completely affected by bactericides[2]. For this reason,foodborn diseases associated with poultry meat consumption are frequently reported and the shelf-life of poultry meat is shorter than red meat[3]. Different methods have been studies for controlling the cross contamination and decontaminate in poultry processing plants. Several chemicals such as organic acids[4],chlorine and chlorine derivates[5],hydrogen peroxide[6],ozone[7],and other compounds[8],have been applied by dip or spray methods. However, most of them altered the visual appearance of skin and meat. Some of them are even suspicious with regards to public health. In addition to those chemicals, electrical stimulation [9],irradiation[10],sonication[11]and heat treatment [12] have also been used as decontamination methods. Organic acids such as acetic and lactic acid, and then derivatives were reported as natural alternatives to increase the shelf-life and microbial safety of food products. Acetic acid and lactic acid have been used by adding to scald or chill water during poultry processing and have given relatively reasonable results[13]. Hydrogen peroxide is a well known germicide in the medical field and has been evaluated in various combinations in the poultry industry from the hatchery to the processing plant[14].This study was performed investigate the effectiveness of acetic acid and hydrogen perioxide in improving microbiological quality of poultry carcasses. Bas.J.Vet.,Res.,Vol.7,No.2,2008 98 MATERIAL AND METHODS Spraying procedures A total of six poultry carcasses were used. The spraying procedures was done on the thigh(12 thigh)half of them were sprayed with acetic acid, the other half were sprayed with hydrogen peroxide for 10s at concentrations derived from a response surface central compo site design. The area was swabbed using the rinse swab method [7]. The area used for sampling (using metallic template)was 5cm 2 . Microbiological analysis After the area was swabbed by sterile swab cotton, decimal serial dilutions were prepared using sterile 0.1% peptone water taking aseptic precautions. In Nutrient Agar and MaCconkey Agar,1ml of each dilution was inoculated in duplicate plate and mixed before solidification. In Mannitol Salt Agar and Eosin Methylen Blue Agar 0.1ml of each dilution were surface plated in duplicate plate. Total mesophilic bacteria in Nutrient Agar incubated for 2days at 32Co,total coli form in MaCconkey Agar incubated for 24h at 32C°,Escherichia coli in Eosin Methylen Blue Agar incubated for 2±24h at 1±32C°,Staphylococcus aureus in Manitol Salt Agar incubate ed for 24-48h at 37Co following the incubation, the colonies on duplicate plates with 30 to 300 colonies were counted using aplate counter and the number of microbes were expressed as colony-forming units per cm 2 as recommended by American Public Health Association[15]and all data were analyzed using SPSS statistical software[16] RESULTS AND DISCUSSION Treatment of poultry meat in water containing 1% acetic acid resulted in a significant reduction for total mesophilic bacteria count, total coli form count, Escherichia coli count and Staphylococcus aureus count with 10.50x10 3 ,1.03x10 3 ,7.5x10 1 and1.05x10 2 cfu/cm 2 , respectively but no alteration on appearance and odour were determine (Table1). Similar results were already reported on decontamination with a cetic acid of poultry carcasses[17]. However, some of them observed that carcasses treated with 1% acetic acid exhibited a yellowing or darkening of the skin of carcasses treated after defeathering. contact time of the acetic acid may be determining factor in appearance changes of the carcasses[18]. Hydrogen peroxide at concentrations of 1% had no microbiological effect on the carcasses. The contact time of 10s used in this study was probably not adequate to reduce microbial numbers. Carcass appearance, had a bleached appearance, very white skin and the skin seemed to be bloated and pliable. These results agree with the data presented by [18] on the appearance of defeathered carcasses. Table 1: Microbial Count ± SD of Chicken Carcasses Treated with Acetic Acid and Hydrogen Peroxide (cfu/cm 2 ). Statistical parameters Microbial groups 1% H2O2 1% acetic acid Without treatment 26.33 ±2.784 x10 3 a 10.50±1.313 x10 3 b 27.47± 2.425x10 3 a Total mesophilcbacteria 2.61 ±0.276 x10 3 a 1.03±0.131 x10 3 b 2.71± 0.261x10 3 a Total Coliform Bacteria 3.70 ±0.52 x10 2 a 7.5±0.5 x10 1 b 4.41± 1.03x10 2 a Escherichia coli 2.63 ± 0.72x10 2 a 1.05 ± 0.13 x10 2 b 2.74±0.24x10 2 a Stphylococcus aureus a ,b denote significant difference at P< 0.05 Bas.J.Vet.,Res.,Vol.7,No.2,2008