A University of Georgia scientist said there is an easy way to keep fresh eggs safe: keep them cold. So even if you stocked up on eggs during the recent sales for Easter, you can keep using them for another month or more.

How long is safe?

"Look on the carton for a 'sell by' or 'use by' date," said Keith Bramwell, an Extension Service poultry scientist with the UGA College of Agricultural and Environmental Sciences. "Eggs, as long as they're kept cold, are safe to eat for about three weeks after that date."

Many shoppers, Bramwell said, don't even know the date is there. "It kind of sneaked up on shoppers," he said. "The date was added without much fanfare. But it's important to know."

Hen decides date

That date, he said, is 30 days after the eggs were packed. And many processors pack them the same day the hen lays them.

"At the farm, the eggs are washed, inspected and cooled within minutes of laying," he said. "Processors keep them cold until they're shipped to stores in two or three days."

Eggs' purpose, and its consequence

That's important because of the basic purpose of eggs, Bramwell said. Eggs are created to support a chicken embryo with nutrients, water and oxygen. "That's perfect for bacteria, too," he said, "if the temperature is warm enough."

Tests show that more than 99.9 percent of eggs don't contain any bacteria, he said, when they leave the processor. But improper handling can contaminate them later.

"If the eggs are kept cold, and that means 40 degrees or colder, any bacteria that might be in the egg can't grow," Bramwell said. "So grocery stores and shoppers need to keep fresh eggs cold, too."

Treat eggs carefully

Elizabeth Andress, an Extension Service food safety scientist with the UGA College of Family and Consumer Sciences, said you should treat eggs like any perishable food.

"Get them from a refrigerated case at the grocery store into the refrigerator at home as quickly as possible," she said.

Though many refrigerators have a built-in egg compartment in the door, that's not the safest place to store them. "Every time someone opens the door," Andress said, "the eggs warm up a bit and lose a little bit of moisture."

Keep them in the foam or pasteboard carton in the coldest part of the refrigerator, she said. The carton provides an added layer of protection.

She also advises against washing eggs before storing them. Washing removes a thin protective layer on the shells that keeps moisture in and helps keep bacteria out.

And cook them completely

And just to be sure they're safe, always eat eggs thoroughly cooked. For fried or scrambled eggs, including omelets, cook them until the white and the yolk are firm, Andress said.

Though it's hard to check the temperature of some egg dishes, she said, that's the best way to check for doneness. Cook custards, puddings, casseroles and other soft egg dishes to 160 degrees to make sure they're safe.

"We used to think cooking eggs, especially hard-cooking eggs, kept them safe longer," Andress said. "Now we know that cooking eggs shortens their storage life to just three or four days."

Other effect time has on eggs

However, unless they get contaminated, the most noticeable effect time has on eggs is a drop in the protein quality.

The usually high-quality protein deteriorates slightly over time, Bramwell said. "And the white, the albumen, gets thicker," he said, "as moisture is lost out of the pores of the shell."