Radio waves make egg pasteurization faster, less expensive

Scientists have developed a new procedure to pasteurize eggs that could reduce illnesses caused by salmonella bacteria.


David Geveke at the U.S. Department of Agriculture’s Agriculture Research Service has developed a system that uses radio waves to heat eggs without changing the egg whites.


Geveke said the system works similar to a standard microwave oven, but it uses a longer radio frequency wavelength, enabling it to penetrate deeper into the egg.


“In our method, RF has further advantages over microwaves in that it can be applied directly to part of the egg, thus avoiding overheating the air cell,” he said in an email.


He said the new process also leaves egg whites clear. Conventional pasteurization methods, which involve hot water immersion, can make the whites look slightly cloudy, although it does not affect the nutritional content or taste.


“An egg pasteurized using our process will look exactly like an unpasteurized egg,” he said.


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The process developed by Geveke, a chemical engineer at the ARS Food Safety Unit in Wyndmoor, Pennsylvannia, is faster, less expensive to use than existing methods and focuses more heat on the yolks than on white portions.


It is also expected to lower the cost of pasteurization and the price of pasteurized eggs in stores.


The thinking is that if pasteurized eggs are more readily available and less expensive, more consumers will choose them and fewer people will contract salmonella-related illnesses.


Test results published by Geveke’s team showed the radio frequency treatment reduced pathogens by 99.999 percent, which is about the same as the conventional hot water method. 


However, it was three times faster than the conventional method, requiring about 20 minutes. It is also expected to reduce the price of pasteurized eggs, which normally cost about $1.50 a dozen more than conventional eggs.


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Geveke said he expects to have a commercial prototype ready next year.


The salmonella bacteria can be killed by properly cooking food before eating.


Pasteurized eggs accounted for less than three percent of the 74 billion fresh eggs bought by U.S. consumers last year, but they are recommended for nursing homes and institutional use, such as hospitals, and for use where raw eggs are used, such as traditional caesar salads and hollandaise sauces.


Salmonella infection can cause cramps, diarrhea and fever.


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