About one of every 20,000 chicken eggs produced in the United States has a high risk of being contaminated with Salmonella bacteria. Harmful to people, Salmonella—notably S. enteritidis—has been associated with eating raw or undercooked eggs. This and other pathogenic Salmonella strains can cause diarrhea, stomach cramps, fever and, in some instances, death.

While only a small fraction of shell eggs may harbor Salmonella, the public health and safety risks posed by the consumption of raw or undercooked eggs stem from the fact that millions of eggs are eaten daily. The public health hazard is greatest for people with weakened immune systems, including the very young, the very old and hospital patients. The U.S. Department of Agriculture (USDA) estimates that pasteurizing all U.S.-produced shell eggs could reduce the number of egg-borne Salmonella illnesses by up to 85 percent, or more than 110,000 cases a year.

Researchers at the USDA and Princeton Plasma Physics Laboratory (PPPL) have developed a novel technique that incorporates radio frequency (RF) energy to uniformly heat the egg while simultaneously bathing it in a cool water bath to rapidly pasteurize eggs in the shell without damaging the delicate egg white, thereby preserving sensory and functional qualities. The process can pasteurize shell eggs in about one-third the time that current methods require, and can produce an egg whose taste and appearance are virtually indistinguishable from those of a fresh, unpasteurized egg.

Researchers at the USDA and Princeton Plasma Physics Laboratory (PPPL) have developed a novel technique that incorporates radio frequency (RF) energy to uniformly heat the egg while simultaneously bathing it in a cool water bath to rapidly pasteurize eggs in the shell without damaging the delicate egg white, thereby preserving sensory and functional qualities.

PPPL has over 40 years of experience in the design of RF and plasma systems. In the late 1990s, the USDA’s Eastern Regional Research Center (ERRC) purchased an RF unit to conduct research on non-thermal pasteurization of liquid foods and entered into collaboration with PPPL through an Interagency Agreement. PPPL modified an RF unit in the ERRC pilot plant and assisted with designing additional units. PPPL also assisted ERRC researchers with the development of RF technology for thermally pasteurizing shell eggs. The research ultimately proved that RF treatment reduces Salmonella in shell eggs by 99.999%.

The USDA has continued the Interagency Agreement with PPPL and entered into a Cooperative Research and Development Agreement (CRADA) with a private company to design, research and develop a large-scale RF pasteurization unit to be available to all egg producers. A prototype unit assembled in conjunction with the CRADA partner is now being tested at the USDA lab. Once completed, development will start on a full-scale unit.