Chemical Method for Determination of Carbon Dioxide Content in Egg Yolk and Egg Albumen

Abstract

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.

MAP storage of shell hen eggs, Part 1: Effect on physico-chemical characteristics of the fresh product

“…As previously reported, the safety, quality and shelf-life of shell eggs are a function of CO 2 content (Keener, LaCrosse, & Babson, 2001). Actually, the beneficial effects of storage in atmospheres enriched in CO 2 on the quality maintenance of fresh eggs are known for many years (Cotterill & Gardner, 1956;Moran, 1937;Sharp, 1930).…”

New technologies to enhance quality and safety of table eggs: ultra-violet treatment and modified atmosphere packaging

“…In terms of pH ( Figure 2B), the albumen of control samples showed an increasing trend from the beginning to the end of storage caused by CO 2 loss through the shell (Keener et al, 2001;Li et al, 1985). The albumen of samples packed in air evidenced quite constant values of pH during storage, while the use of 100% CO 2 was responsible of a fast and marked pH decrease (of about 1.5-2 points) as a consequence of CO 2 solubilisation in the albumen.…”

Determination of the CO2 mass diffusivity of egg components by finite element model inversion

“…At 0, 24, 48 and 72 h the samples of thin albumen, thick albumen and yolk were analysed to measure the total carbon dioxide content (free and combined) by the chemical method propose by Keener, LaCrosse, and Babson (2001). Brooks and Pace (1938) suggested that the proportion between free and combined CO 2 depends on constituent typology: for the thin albumen the percentage of free CO 2 is about 39%, for the thick albumen is about 40% and for the yolk is about 70%.…”

“…The yolk samples were posed in 25 ml beaker, reaching a thickness of about 10 mm, similar to yolk radius in eggs. The concentration was measured following the method of Keener, LaCrosse, and Babson (2001) on samples packed in 100% CO 2 atmosphere at 0, 24, 48 and 72 h.…”

“…After 0, 24, 48 and 72 h the concentration of total CO 2 present in albumen and yolk was determined by the method proposed by Keener, LaCrosse, and Babson (2001). Is has to be underlined that with the Keener method it is not possible to observe a point value of CO 2 concentration but just a volume averaged value.…”