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Title: Effects of processing on the microbiology of commercial shell eggs in the United States.

item Musgrove, Michael
item Jones, Deana
item Northcutt, Julie
item Cox Jr, Nelson

Submitted to: European Poultry Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 8/14/2006
Publication Date: 9/11/2006
Citation: Musgrove, M.T., Jones, D.R., Northcutt, J.K., Cox Jr, N.A., Harrison, M.A. 2006. Effects of processing on the microbiology of commercial shell eggs in the United States.. European Poultry Conference Proceedings.

Interpretive Summary:

Technical Abstract: In the United States, shell eggs are washed and graded prior to retail. Since passage of the Egg Inspection Act in 1970, processing guidelines have been set to ensure that external and internal characteristics are improved. However, less is known about the safety of commercially processed shell eggs. In order to determine genus or species of enteric bacteria entering plants and persisting throughout processing, eggs were collected from three U.S. commercial shell egg processing plants on three separate visits. Five different shell egg surface populations (aerobic, yeasts/molds, Enterobacteriaceae, Escherichia coli, and Salmonella) were monitored at twelve points along the processing line. Three commercial facilities were each visited three times allowing for the sampling of 990 eggs and subsequently analyzed by 5,220 microbiological samples. Though variations existed in levels of microorganisms recovered from plant to plant, the patterns of fluctuations for each population were similar at each plant. On average, aerobes, yeasts/molds, Enterobacteriaceae, and E. coli prevalence were reduced by 30%, 20%, 50% and 30%, respectively, by end of processing. Log10 CFU/ml rinse on eggs collected from packer head lanes were decreased by 3.3, 1.3, 1.3, and 0.5, respectively, when compared to rinses from eggs collected at the accumulator. Also, isolates of Enterobacteriaceae were randomly selected and identified to genus or species by biochemical testing. Several genera and species were detected at each of the three plants. Sites from which the greatest numbers of isolates were identified were those collected from eggs during pre-processing (accumulator, pre-wash rinse) or eggs judged as dirty (re-wash belt entrance or exit). Sites yielding the smallest number of isolates were those during or at the end of processing. Salmonella was recovered from 0–48% of pooled samples in the three repetitions. More Salmonella was recovered from pre-processed than in-process or ready to pack eggs. These data demonstrate that current commercial practices decrease microbial contamination of egg shell surfaces.