Submitted to: Poultry Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/3/2008
Publication Date: 6/1/2008
Citation: Patterson, P.H., Koelkebeck, K.W., 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: Production – part 1. Poultry Science.87(6):1182-1186. Interpretive Summary: Egg temperature can play a critical role in the potential growth of microorganisms in consumer eggs. The quicker an egg can be cooled to 7.2 C (45 F) the lower the likelihood of growth of foodborne pathogens. This study was conducted to gain an understanding of the temperature changes that occur in the shell egg from the time it is laid (oviposition) til it reaches the processing facility. The study was a nation-wide effort and conducted across seasons to gain incite into environmental temperature effects. Egg temperature was significantly different between the states monitored. Environmental house temperature and internal egg temperature were higher during the summer compared with winter. Eggs cooled more quickly during the summer compared to winter. The results of this study provide information which egg producers can utilize to enhance the safety and quality of the egg they produce. These enhancements can occur through targeted management practices which will be different for the seasons of the year.
Technical Abstract: During the hearings on the Egg Safety Action Plan in Washington, DC, many questions were raised concerning the egg temperature (T) patterns used in the risk assessment model. Therefore, a national study was initiated to determine the T of eggs from oviposition through distribution. In Part 1 researchers from Extension and USDA-ARS, in CA, CT, GA, IA, IL, NC, PA and TX gathered data on internal and surface egg T from commercial egg production facilities. An infrared thermometer was used to rapidly measure egg surface T, and interior T was determined by probing individual eggs. The main effects were geographic region (state) and season evaluated in a factorial design. Egg T data was recorded at specific locations in the production facilities in order to standardize the comparisons. Regression analysis (P < 0.0001) showed the R2 (0.952) between infrared egg surface T and interior T was very high and validated further use of the infrared thermometer. Hen house egg surface and interior T were significantly influenced by state, season, and the state*season interaction (P < 0.0001). Mean hen house egg surface T was 27.3 and 23.8 C for summer and winter, respectively, with 29.2 and 26.2 C for egg interior (P < 0.0001). Hen house eggs from CA had the lowest surface and interior T in winter among all the states (P < 0.0001) while the highest egg surface T were recorded during summer in NC, GA and TX, and the highest interior T from TX and GA compared to the other states. Cooling of warm eggs following oviposition was significantly influenced by season, state and the interaction. The definition of ¾ cool is the interior T of the egg when it has reached ¾ of ambient hen house T from its initial internal T at oviposition. Egg internal T when ¾ cool was higher in summer vs. winter and higher in NC and PA compared to IA. The time required to ¾ cool eggs was greater in winter (because of lower hen house T) than summer and greater in IA compared to other states. These findings clearly showed seasonal and state impacts on ambient T in the hen house that ultimately influenced egg surface and interior T. More importantly, they show opportunities to influence cooling rate to improve interior and microbial egg quality.