The influence of rapid air cooling and carbon dioxided cooling and subsequent storage in air and carbon dioxide on shell egg quality

Department of Food Science, North Carolina State Univesity, Raleigh, 27695-7624, USA. kevin_keener@ncsu.edu

This study examined the effect of rapid cooling with air and CO2 on shell egg quality over 14 wk. The 240 fresh eggs were initially heated to 47 C for 24 h in an incubator, cooled using rapid air cooling or CO2 cooling, and then stored in air or CO2 in 250-mL jars for 14 wk. The CO2 levels were recorded of the jar atmosphere, of the egg air cell, and of the egg albumen. The Haugh units of each egg, pH, and of albumen from five eggs per group were also recorded. Haugh units are a logarithmic, empirical relationship between albumen height and egg weight (Stadelman, 1995). Haugh units for the control eggs averaged 70.8 over 10 wk of the study. The control eggs were of such poor quality that they could not be sampled after 10 wk. The air-cooled and CO2-stored eggs averaged 70.3 Haugh units over the 14-wk storage period; however, the egg quality significantly deteriorated after 10 wk. The CO2-cooled and CO2-stored eggs averaged 75.9 Haugh units over the 14 wk study, with no observable decrease in quality. Rapid air-cooling produces a lower quality egg than rapid cooling with CO2. Subsequent storage of rapidly air-cooled eggs in C02 may increase shelf life, but Haugh units were not statistically different from rapid air-cooled eggs. CO2-cooling and subsequent storage in CO2 increased Haugh units. The shelf life of shell eggs could be extended to greater than 14 wk when the eggs were CO2-cooled and CO2-stored.