BACTERIOLOGICAL CHARACTERISTICS OF WASHED AND UNWASHED LAYING HEN’S EGGS

Abstract

To assess the bacteriological quality of washed and unwashed eggs obtained in four commercial poultry farms located in the metropolitan area of Goiânia, Goiás, Brazil was the purpose of this study. Farms 1 and 2 were considered as medium and small production capacity, respectively, and washed mechanically the eggs with heated water containing sanitizing while farms 3 and 4 produced unwashed eggs. The sample universe was made up of 576 eggs from farms 1 and 2, 288 obtained from the poultry facilities and other 288 collected in the classification hall, and 132 obtained in farms 3 and 4, half of this collected in the facilities and the other half in the classification hall. It was considered commercial eggs classified as large eggs from 30 to 40 weeks of age Dekalb White hens. The experimental design was a completely randomized design in a factorial arrangement 2 x 2 (washing procedure x collection place) with three replicates and the experimental unit consisted of pool of six eggs. Counts of mesophilic and positive Staphylococcus coagulase and Most Probable Number (MPN) of total and fecal coliforms in shells and internal content of eggs and Salmonella spp. research in eggshells were made. Results of the counts were expressed as log CFU/g and “t” Student test (5%) adopted. Descriptive and frequency analysis was used to analyse MPN of total and faecal coliforms. Counts of mesophilic and positive Staphylococcus coagulase in eggshells of washed eggs in the classification hall of the farm 1 were lower (p <0.05) than that eggs collected in hen’s facilities which showed the efficiency of sanitization and good bacteriological quality of eggshell. The eggshells obtained in the classification hall of the farm 3 showed a higher (p <0.05) counts of mesophilic than in the facilities. Despite the high counting for positive Staphylococcus coagulase in the classification halls of farms 3 and 4, these values are lower than those needed to form toxin capable of causing human intoxication. Although low frequency (2.1%), it was verified the presence of faecal coliforms in number greater than 100 germs/g of eggshell in the classification hall of the farms that washed mechanically the eggs. It was not observe the presence of Salmonella spp. in all the eggshells collected neither contamination in contents of the eggs. It was concluded that washed eggs from commercial egg farms had better eggshell bacteriological quality than unwashed eggs but the washing process adopted was not able to completely eliminate the fecal coliforms.
KEY WORDS: Commercial eggs, egg washing, food safety, microbiological contamination.