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Taking just a few seconds to rapidly cool freshly laid eggs adds weeks to their shelf life, a new study shows.
The rapid-cooling process uses liquid carbon dioxide to stabilize the proteins in egg whites so much that they could be rated AA—the highest grade for eggs—for 12 weeks. Eggs cooled under current methods lose the AA grade in about half the time. Earlier research showed that the same cooling technology could significantly reduce occurrences of salmonella illnesses.
“There is no statistical difference in quality between eggs as measured by Haugh units just after laying and rapidly cooled eggs at 12 weeks,” says Kevin Keener, professor of food science at Purdue University. “This rapid-cooling process can provide a significant extension in the shelf life of eggs compared to traditional processing.” Haugh units measure an egg white’s protein quality.
The rapid-cooling technology takes liquid carbon dioxide and turns it into a “snow” to rapidly lower the eggs’ temperature. Eggs are placed in a cooling chamber and carbon dioxide gas at about minus 110 degrees Fahrenheit is generated. The cold gas is circulated around the eggs and forms a thin layer of ice inside the eggshell. After treatment, the ice layer melts and quickly lowers an egg’s internal temperature to below 45 degrees, the temperature at which salmonella can no longer grow.