Safer liquid eggs

Researchers at the USDA Agricultural Research Service’s Eastern Regional Research Center (ERRC) have filed a patent on technology that can further protect pasteurised liquid eggs from food safety threats. These threats include both naturally occurring spoilage bacteria and pathogens such as Salmonella enteritidis, the primary cause of egg-related foodborne illness. The technology has also been successfully applied to milk.

The new technology, developed by ERRC scientists Sudarsan Mukhopadhyay, Peggy Tomasula and John Luchansky, may help reduce the 40,000 cases of salmonellosis and other illnesses related to raw egg product consumption that occur every year in the US.

“Current pasteurisation technology is not adequate to remove all pathogens effectively from egg products,” says Tomasula, research leader of the ERRC Dairy Processing and Products Research Unit. “Though pasteurisation eliminates heat-sensitive pathogens, some heat-resistant microorganisms can survive and spoil liquid egg whites.”

However, the research team has found that new technology can compensate for the shortcomings of thermal pasteurisation.

The technology, called ‘crossflow microfiltration membrane separation’ (CMF), removes more pathogens than thermal pasteurisation. And it does so without affecting the eggs’ ability to foam, coagulate, and emulsify — meaning that CMF-treated eggs could be safely substituted for pasteurised eggs in products where those characteristics are desired, such as cakes and mayonnaise. In a pilot-scale study, CMF was shown to remove about 99.9999% of inoculated S. enteritidis from unpasteurised liquid egg whites.

The technology can also be used to remove Bacillus anthracis spores from egg whites. This finding adds to previous work in which ERRC researchers used CMF to remove 99.9999% of B. anthracis spores inoculated into fluid milk. Microfiltration can also protect milk from more common bacterial pathogens, potentially extending its shelf life.

Though effective in its own right, CMF works best when treated as an accompaniment to pasteurisation, not a replacement for it, says Tomasula. Combining the two processes significantly reduces the pathogen load.