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 d ioxide content. A commercial process was recently developed for rapidly coo ling shell eggs by using cryogenic CO2. The benefit of this new process ove r existing cooling processes is that the CO2 addition during cryogenic cool ing provides additional safety and quality enhancements. In order for these benefits to be fully developed into a process that can be adopted by the e gg 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 meth ods were not adequate for determining CO2 content. They did not prevent CO2 loss during neutralization. A simple and accurate method for determining C O2 content in acidified egg albumen and yolk samples was developed. This me thod involves the liberation of CO2 from an acidified egg sample into a sta ndardized, dilute sodium hydroxide solution inside a sealed jar. The egg sa mple and a small beaker containing the standardized sodium hydroxide soluti on are placed in a glass jar and sealed. Next, a concentrated acid phosphat e solution is injected through a rubber septum in the cap of the jar onto t he egg sample, while avoiding contact with the sodium hydroxide solution. T he 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 sod ium hydroxide solution. Afterwards, the dilute sodium hydroxide solution is removed and titrated to the phenolphthalein endpoint using a dilute, stand ardized hydrochloric acid solution. The amount of hydrochloric acid solutio n required for neutralization can be directly related to CO2 content in the sample.