Junkfood Science: Eggsactly: Fun egg facts to help you keep safe and save money

January 11, 2007

Eggsactly: Fun egg facts to help you keep safe and save money

If you throw away eggs the moment they go past that sell-by date printed on the carton for fear the eggs are unsafe to eat, then you’ll find this study from U.S.D.A. Agricultural Research Service food technologists good news. The researchers specifically looked at the bacteria which can contaminate eggshells: Enterobacteriaceae, which includes salmonella, escherichia, enterobacter, klebsiella and yersinia.

What do egg dates really mean?

...Agricultural Research Service food technologists Mike Musgrove and Deana Jones of the Poultry Processing and Meat Quality Research Unit in Athens, GA, tested the quality and functionality of eggs during 10 weeks of storage — well beyond the current 30-day industry standard for keeping eggs on the store shelf. Properly refrigerated, eggs are considered safe for consumption four to five weeks beyond the date they are packed....

"Most eggs are sterile when formed, but may become contaminated as they exit the hen's body or from any surface they contact," says Musgrove. Fortunately, cleansing procedures protect the consumer from the bacteria. Eggs are washed with water that is between 90 degrees F and 120 degrees F, then rinsed with hot water and chlorine. The eggs are then placed in cold storage and shipped.

"Repeated testing of eggs after washing and packaging showed no Enterobacteriaceae bacteria contamination until the fifth week after processing. Fewer bacteria on the surface of the egg means fewer can get into the egg when they are cracked in preparation for consumption."

...[O]ver time, eggs can lose their ability to fluff up an angel food cake or make mayo creamy. Does this happen at the sell-by date? Not according to Jones. "During our study of egg functionality over 10 weeks of storage, we found no marked decrease in quality," she says. "Angel food cakes were light and fluffy using eggs stored up to 10 weeks."

And safety isn't an issue for eggs that are fully cooked, since the high temperature destroys harmful microbes.

So what are we to make of the sell-by date? "Egg quality isn't affected for quite a long time, which allows for storage beyond the sell-by date," says Jones. Musgrove's data shows that current federal guidelines for producing and processing eggs appear to have a beneficial effect on microbial contamination -- even during long-term storage -- thus giving an extra cushion of safety and quality.

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