The Relationship between the Level of Salmonella Enteritidis and the Temperature at Which Eggs Have Been Held from the Day of Lay until the Day of Processing
University of Georgia
Dr. Jinru Chen
Previous research indicated that storage temperature had a significant influence on the quality and safety of eggs. In Part I of the study Salmonella inoculated eggs were stored at 4°C (39.2° F), 10°C (50° F), and 22°C (71.6° F) and for storage times of 0, 1, 2, 3, and 4 weeks. None of the control eggs were found to be contaminated with Salmonella Enteriditis. Also, the microbial populations were not significantly different in eggs that were laid in different seasons. The populations of artificially inoculated Salmonella were not significantly different in eggs stored at 4° C versus 10° C. In addition, at 10° C there was no significant increase or decrease in the Salmonella numbers in the artificially inoculated eggs. However, eggs stored at 22° C had significantly higher growth and populations of Salmonella, thus showing egg storage should be done at the lower temperatures to prevent the growth of Salmonella. In Part II of the study fresh chicken eggs, both liquid egg and egg shells, were sampled for Salmonella over a one year period. Eggs were stored at 4, 10, and 22° C and sampled during a four week storage period as described in Part I. Out of the 960 liquid egg samples and 960 egg shell samples in the study 14 microbial isolates were found. None of these isolates was Salmonella.
This study reinforced the importance of maintaining low temperatures in controlling and preventing the growth of Salmonella Enteritidis from the point were the eggs are laid until the eggs are processed for human consumption. This should be easy to achieve and cost effective and thus should be of particular value to small and very small egg plants. However, plants will need to validate that their methodology achieves these parameters.
This research should decrease their operating cost while helping them to ensure food safety and public health protection.
The full report on this research can be found on the Fiscal Year 2005 table under the column Food Safety Technologies - Additional Information.