Chemical method for determination of carbon dioxide content in egg yolk and egg albumen

The safety, quality, and shelf life of shell eggs is a function of carbon dioxide content. A commercial process was recently developed for rapidly cooling shell eggs by using cryogenic CO2. The benefit of this new process over existing cooling processes is that the CO2 addition during cryogenic cooling provides additional safety and quality enhancements. In order for these benefits to be fully developed into a process that can be adopted by the egg industry, and thus realized by the consumer, the amount of CO2 absorbed by the egg during this process needs to be quantified. Because the albumen pH of rapidly cooled eggs was reduced to pH <6.5, existing titrametric methods were not adequate for determining CO2 content. They did not prevent CO2 loss during neutralization. A simple and accurate method for determining CO2 content in acidified egg albumen and yolk samples was developed. This method involves the liberation of CO2 from an acidified egg sample into a standardized, dilute sodium hydroxide solution inside a sealed jar. The egg sample and a small beaker containing the standardized sodium hydroxide solution are placed in a glass jar and sealed. Next, a concentrated acid phosphate solution is injected through a rubber septum in the cap of the jar onto the egg sample, while avoiding contact with the sodium hydroxide solution. The sample is then stored at 37 C for 24 h. During this storage period, the carbon dioxide is released from the egg sample and is absorbed into the sodium hydroxide solution. Afterwards, the dilute sodium hydroxide solution is removed and titrated to the phenolphthalein endpoint using a dilute, standardized hydrochloric acid solution. The amount of hydrochloric acid solution required for neutralization can be directly related to CO2 content in the sample.