Submitted to: Poultry Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/13/2007
Publication Date: 6/1/2008
Citation: Koelkebeck, K.W., Patterson, P.H., Anderson, K.E., Darre, M.J., Carey, J.B., Ahn, D.U., Ernst, R.A., Kuney, D.R., Jones, D.R. 2008. Temperature Sequence of Eggs from Oviposition Through Distribution: Processing - Part 2. Poultry Science.87(6):1187-1194. Interpretive Summary: Previous research has found shell egg quality decreases at a greater rate at an internal egg temperature above 7.2 C (45 F). Temperatures above 7.2 C are also more favorable for bacterial growth, including foodborne pathogens. Eggs are often eaten in lightly cooked foods which can pose an increased risk for food safety. The proper cooling of eggs during the production, processing and transportation of shell eggs can help to maintain high physical and microbial quality. This study was conducted to determine the changes in egg temperature during production, processing and transportation. The current portion focuses on temperature changes during shell egg processing. According to federal recommendations, eggs are washing in hot water. Previous research has found egg temperature increases during this time. During this national survey, egg temperature was monitored during the summer and winter. Geographically, egg temperatures were different. Furthermore, eggs produced during the winter had a lower temperature than summer ones. Eggs increased in temperature as they went through the processing line. Winter eggs had a greater internal temperature increase during processing than summer eggs. The results of this study indicate that processors and regulators could consider altering some processing practices seasonally to enhance the physical and microbiological quality of shell eggs as it pertains to egg temperature.
Technical Abstract: The Egg Safety Action Plan released in 1999 raised many questions concerning egg temperature used in the risk assessment model. Therefore, a national study by researchers from CA, CT, GA, IA, IL, NC, PA, and TX was initiated to determine the internal and external temperature sequence of eggs from oviposition through distribution. Researchers gathered data from commercial egg production, processing and distribution facilities. The experimental design was a mixed model with two random effects for season and geographic region, and a fixed effect for operation type (in-line or off-line). For this report, internal and external egg temperature data were recorded at specific points during processing in the winter and summer months. In addition, internal egg temperatures were recorded in pre- and post-processing cooler areas. There was a significant season by geographic region interaction (P < 0.05) noted for both surface and internal egg temperatures. As expected, winter egg temperatures were lower than in summer, but eggs gained in temperature from the accumulator to the post-processing cooler. During all phases of processing, summer egg surface and internal temperatures were greater (P < 0.05) than during the winter. When examining the effect of processing time and conditions, it was found that 2.4 and 3.8 C were added to egg surface temperatures and 3.3 and 6.0 C were added to internal temperatures in the summer and winter, respectively. Internal egg temperatures were higher (P < 0.05) in the pre-processing cooler area during the summer vs. winter months and internal egg temperatures were higher (P < 0.05) in the summer when eggs were considered to be ¾ cool in the post-processing area. This ¾ cool is the point on the cooling curve that internal egg temperature would be at when they reached ¾ cool (temperature change required to meet USDA-AMS storage regulation of 7.2 C). However, the cooling rate was not different (P > 0.05) for eggs in the post-processing cooler area in the summer vs. winter. Therefore, these data suggest that season of year and geographic location can affect the temperature of eggs during processing and should be a component in future assessments of egg safety.