Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 9, 2005
Publication Date: November 1, 2005
Citation: Musgrove, M.T., Jones, D.R., Northcutt, J.K., Harrison, M.A., Cox Jr, N.A. 2005. Impact of commercial processing on the microbiological safety and quality of shell eggs. Journal of Food Protection. 68(9):2367-2375. Interpretive Summary: HACCP regulations are being written for the commercial shell egg industry. In order for these regulations to be effective in assisting shell egg packers in improving food safety, they must be based on scientific information. Eggs were collected from shell egg processing plants at twelve points along the processing chain, from the point where the eggs enter the plant until they were ready to be packaged. Five bacterial populations associated with the shells of eggs (aerobic microorganisms, yeasts/molds, Enterobacteriaceae, E. coli, and Salmonella) were monitored to determine their fluctuations throughout the process. All five of these populations were significantly decreased by the commercial process. This information will be useful to the industry and to regulatory agencies as they formulate HACCP plans and regulations. This foundation research has provided a baseline for five important microbial populations.
Technical Abstract: Egg shell microbiology has been studied extensively over the years though little of it describes how modern U.S. processing conditions impact microbial populations. As regulations are being drafted for the industry, such information can be important in determining processing steps that are critical to product safety. Five different shell egg surface populations (aerobic, yeasts/molds, Enterobacteriaceae, Escherichia coli, and Salmonella) were monitored at twelve points along the processing line (accumulator, pre-wash rinse, washer one, washer two, sanitizer, dryer, oiler, scales, two packer head lanes, re-wash entrance, re-wash exit). 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. 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.