Cracking the Date Code on Egg Cartons

Alice Henneman, MS, RD, UNL Extension in Lancaster County
Joyce Jensen, REHS, CFSP, Lincoln-Lancaster County Health Department


Is there a way to tell from the egg carton how old the eggs are? Are there some guidelines for how long eggs are safe to eat?

Pack dates and sell-by datesEGG CARTON

According to the U.S. Dept. of Agriculture (USDA), "Many eggs reach stores only a few days after the hen lays them. Egg cartons with the USDA grade shield on them must display the "pack date" (the day that the eggs were washed, graded, and placed in the carton). The number is a three-digit code that represents the consecutive day of the year (the "Julian Date") starting with January 1 as 001 and ending with December 31 as 365. When a "sell-by" date appears on a carton bearing the USDA grade shield, the code date may not exceed 45 days from the date of pack."

Plants not under USDA inspection are governed by the state laws where the eggs are packed and/or sold. Most states require a pack date as described in this article. For more information about state egg laws, contact your state's Department of Agriculture.

How long to keep eggs

USDA advises (pdf): "Always purchase eggs before the "Sell-By" or "EXP'" date on the carton. After the eggs reach home, refrigerate the eggs in their original carton and place them in the coldest part of the refrigerator, not in the door. For best quality, use eggs within 3 to 5 weeks of the date you purchase them. The 'sell-by' date will usually expire during that length of time, but the eggs are perfectly safe to use."

Use of either a "sell-by" or an "Expiration" (EXP) date is not federally required but may be State required in some states.

"If by chance you have an egg that you have removed from the carton and no longer know when it was packed or purchased, it may be difficult to determine its freshness," according to Marcia Greenblum, MS, RD, Associate Director, Education Outreach, Nutrition and Food Safety, Egg Nutrition Center.

"The test of freshness that involves seeing if an egg floats in a glass of (salt)-water is not a reliable test. In fact, this test has no relationship to the freshness of shell eggs. While eggs do take in air as they age, the size of the air cell varies from egg to egg when they are laid. Therefore, a freshly laid egg and an older egg might react very similarly," says Greenblum.

When unsure about the safety of your eggs, as with all foods, when in doubt, throw them out.

How to cook eggs safely

Proper cooking as well as proper storage is important for egg safety. Cook eggs thoroughly so both yolks and whites are firm, not runny. Casseroles and dishes containing eggs should be cooked to 160° F as measured by a food thermometer. Do not eat raw or undercooked eggs. Once eggs are hard-cooked, they should be refrigerated (in their shells) within 2 hours of cooking and used within a week. Refrigerate them in a clean container, not their original egg carton.

For more information about eggs, check the USDA website.

Eggs and your health

Eggs are a source of high quality protein and are nutrient-dense, containing only 75 calories while providing several essential nutrients. Two carotenoids, lutein and zeaxanthin, are both abundant in egg yolks, and help protect against macular degeneration, the leading cause of blindness in Americans age 65 and older.

Did you know ... today's eggs are lower in cholesterol and higher in vitamin D? Nutritional data from USDA researchers indicates the yolk of a large egg contains 41 IU of Vitamin D which is 64 percent more  than in 2002. Cholesterol is down 14 percent to 185 milligrams from a previous level of 220 milligrams.

The 2010 Dietary Guidelines for Americans recommend individuals consume less than 300 milligrams of cholesterol a day and state:

Independent of other dietary factors, evidence suggests that one egg (i.e., egg yolk) per day does not result in increased blood cholesterol levels, nor does it increase the risk of cardiovascular disease in healthy people. Consuming less than 300 mg per day of cholesterol can help maintain normal blood cholesterol levels. Consuming less than 200 mg per day can further help individuals at high risk of cardiovascular disease.

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