Once eggs are laid, their natural resistance to pathogens begins to wear down but a Purdue University scientist believes he knows how to rearm those defences.
Kevin Keener, an associate professor of food science at Purdue University, created a process for rapidly cooling eggs that is designed to inhibit the growth of bacteria such as salmonella. The same cooling process would saturate the inside of an egg with carbon dioxide and alter pH levels, which he has found are connected to the activity of an enzyme called lysozyme, which defends egg whites from bacteria.
"This enzyme activity is directly related to the carbon dioxide and pH levels," said Dr Keener, whose results were published in the journal Poultry Science. "An increase in lysozyme would lead to increased safety in eggs."
Freshly laid eggs are saturated with carbon dioxide and have pH levels of about 7. Over time, the pH level rises to 9 and carbon dioxide escapes, Dr Keener said. As that happens, lysozyme becomes less active.
The cooling process would create the same conditions, he said.Dr Keener continued: "When we cool the eggs, carbon dioxide is sucked inside the shell. We're able to resaturate the white of the egg with carbon dioxide, returning it to that original condition when the chicken laid it."
Dr Keener said Food and Drug Administration studies show that if eggs were cooled and stored at 45ªF or less within 12 hours of laying, there would be an estimated 100,000 fewer salmonella illnesses from eggs in the United States each year.
Dr Keener will continue to study the molecular changes that occur with egg cooling.
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