VARIATIONS IN EXTERNAL AND INTERNAL MICROBIAL POPULATIONS OF SHELL EGGS DURING EXTENDED STORAGE

Authors: Jones, Deana; Musgrove, Michael; Northcutt, Julie

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/19/2004
Publication Date: 12/1/2004
Citation: Jones, D.R., Musgrove, M.T., Northcutt, J.K. 2004. Variations in external and internal microbial populations of shell eggs during extended storage. Journal of Food Protection. 67(12):2657-2660.

Interpretive Summary: Unwashed and washed shell eggs were compared for external and internal microbial contamination during extended storage. Total aerobic bacteria, yeast and mold, Enterobacteriaceae and pseudomonads were enumerated. Washed eggs had fewer bacteria present on the shell surface throughout the 10 weeks of storage for all populations monitored. The contents of both unwashed and washed eggs had low levels of organisms present during the storage period. The results indicated that while previous work has shown plant sanitation practices to be less than effective, current shell egg processing procedures produce clean, safe eggs for the consumer.

Technical Abstract: The current project was conducted to determine the microbial quality of commercially processed shell eggs during extended storage. Control eggs (CE) were collected at the accumulator before entering the processing line. Washed eggs (WE) were retrieved after placement in flats. All eggs were stored on pulp flats at 4ºC for 10 weeks. Twelve eggs from each treatment were rinsed on the day of collection and each week of storage. After rinsing, eggs were sterilized in ethanol and contents aseptically collected. Total aerobes, yeasts and molds, Enterobacteriaceae and pseudomonads were enumerated for shell rinses and pooled egg contents. During storage, no differences were found between CE and WE for Enterobacteriaceae and pseudomonads in either shell rinses or contents. No differences were found between treatments for population levels of total aerobes or yeasts and molds in the egg contents throughout the storage period. Significant differences occurred at each week of storage for external shell contamination by total aerobes between treatments. The greatest level of CE contamination occurred at 8 wk of storage and lowest at 0 and 1 wk of storage. The highest level of shell contamination with aerobic bacteria in the WE was found at 0 wks of storage and the lowest level at 7 wk. Yeast and mold contamination levels were also significantly different during each week of storage between treatments for shell rinses. Although previous plant sanitation sampling indicated high levels of bacterial contamination, commercially washed eggs were significantly less contaminated than unwashed eggs for the populations monitored.