‘Unique’ rapid egg cooling system to cut salmonella risk, extend shelf life

Tuesday 31 August 2010

A rapid egg cooling system that uses carbon dioxide to create a thin layer of ice on the inside of the shell would cut salmonella illnesses and significantly extend product shelf life, said the US scientist spearheading the development.

Associate professor Kevin Keener, of Purdue University in Indiana, said the fast cooling of eggs after laying and processing would “significantly reduce the ability of salmonella to grow inside the egg and potentially keep consumers from becoming sick”.

Egg recall
The US is currently enacting a recall of at least half a billion eggs as people have been sickened by salmonella across the country.

Keener was quick to point out that ‘natural contamination’ from shell eggs was relatively rare and the current problems were more likely to have arisen because of sanitation failures within the processing environment.

"There is a big discussion right now about how food safety in the US is regulated and cooling eggs is part of that debate," he told

Six days
Federal guidelines on how quickly eggs should be cooled do not currently exist – but Keener pointed out that under present industry practices, it can take up to six days for eggs to cool to 45F (7C) – the temperature at which salmonella can no longer grow.

Keener said eggs can be more than 100 F (38 C) after washing and packaging in cartons. Thirty dozen eggs are then packed in a case, and 30 cases are stacked onto pallets and placed in refrigerated coolers. The eggs in the middle of the pallet can take up to 142 hours to cool to 45 F degrees. He said scientists estimate that one in about every 20,000 eggs has salmonella naturally inside.