New Radio-Wave Technique Kills Salmonella in Raw Eggs

A new technique developed by USDA scientists can pasteurize raw, in-shell eggs without ruining their taste, color, or texture—potentially rendering raw or undercooked eggs safer for use in foods like Caesar salad and eggnog.

The pasteurization process, now in prototype stage, positions each raw egg between two electrodes that send radio waves back and forth through it. At the same time, the egg is sprayed with water, to compensate for some of the heat created by the radio waves. This process warms the egg from the inside out, protecting the delicate egg white, which is more sensitive to heat.

It also takes only 20 minutes to kill 99.999 percent of Salmonella that the researchers injected into their test eggs, compared with the hour-long hot water immersion process that is currently the only commercially used method of pasteurizing raw in-shell eggs in the U.S.

That process also can compromise egg quality, says David Geveke, PhD, a USDA chemical engineer who was one of the lead developers of the new technique. “Eggs pasteurized with the hot water immersion process are somewhat cloudy and hazy. Our processed eggs come out as clear as a brand-new egg. There are advantages in some of the functional properties as well.”

On April 8, the USDA signed a Cooperative Research and Development Agreement with a company that will scale up the process for commercialization (the company’s name could not yet be disclosed).

“We envision equipment that uses something more like a conventional size washer for egg processing, with at least six eggs in a row on multiple rows,” says Dr. Geveke. “I don’t think the mechanical part will be the most challenging; the hard part will be mating the radiofrequency to the eggs as they’re moving along.”

The CRADA is a two-year agreement, and Dr. Geveke says that the goal is to have the commercial product ready by the end of the agreement period.


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