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Eggs are a healthy food choice. They are high in protein, low in saturated fat, and packed full of beneficial vitamins, minerals, and antioxidants. They belong in a well-stocked refrigerator. 

Sometimes though, life happens. We purchase healthy fresh foods then forget to use them. Nothing can ruin your day faster than a rotten egg. 

In this article, we will discuss how to properly store eggs, how long a carton of eggs should last, and provide a few simple tricks to help you learn how to tell if an egg is still good. 

5 Easy Ways to Tell If an Egg Is Still Good

The bad news is that you cannot identify a spoiled egg by sight alone.

The good news is that if you find older eggs in your fridge and suspect they are past their prime, a few simple tests can help you decide if they are safe to eat or should be thrown away.

Here are five easy ways to test if your eggs are still good.

Check the Egg Carton Date

Many states require a sell-by date or expiration date on the side of egg carton packaging. 

The expiration date represents the date when eggs are no longer considered fresh (1). It is meant for retailers to help manage their inventory and does not necessarily mean eggs need to be discarded once it has been reached unless there are noticeable signs of spoilage such as cracks or odors.

Some egg cartons do not have an expiration date printed on them. However, eggs that have been graded by the USDA will be marked as grade AA or grade A on the front of the carton of eggs. Graded eggs are required to have a pack date printed on the carton (2). 

The pack date is different than the expiration date. It represents the date when the eggs were washed, graded, and packaged, and is generally very close to the date when the eggs were laid by a hen. 

The pack date will not be a standard date in the format we are used to seeing on foods. Instead, the pack date is displayed as a three-digit code known as the Julian date. This date represents the day of the year when the eggs were packaged. 

Julian dates go in chronological order so January 1 will be 001 and December 31 will be 365. As an example, if you see 181 printed on the carton this means the eggs were packed on June 30th. 

Other egg cartons have a sell-by date instead of an expiration date on them. Per the USDA, the sell-by date cannot be more than 30 days after the Julian date or pack date (2).

If your eggs have expired based on date displayed on the egg carton but are still within a two to three week window of that date, do not just throw them away. Use the float test described below to determine if they are still good eggs or if they should be disposed of.

Candling

This is the process of using light to determine the quality of an egg. In the old days this process was done with actual candles, now large egg producers use equipment that can detect cracked shells and defective eggs.

To do this test at home, bring your eggs into a dark room. You will need a bright source of light such as a small flashlight (3).

Hold your egg close to the light source between your index finger and thumb. The light should illuminate the shell and allow you to “see” inside the egg. 

Using the light source you should be able to see the air bubble that develops in the top end of the egg. The larger the air bubble, the older the egg, and the more likely it is to float in a bowl of water. 

You should also see very little movement of the egg contents when you move the egg from side to side. This indicates freshness. The contents of an older egg will move more freely within the shell.

While the candle method will allow you to see the size of the air bubble inside an egg and give you some indication of overall freshness, like the egg carton dates it will not tell you if your egg has gone bad. 

The easiest way to be sure your expired eggs or eggs that fail the light test are still ok to eat is to use the egg float test.

Float Test

The egg float test is one of the most popular ways to test if old eggs are still ok to eat.

Freshly laid eggs have no air pocket within the egg shells. The mandated USDA washing and processing of eggs reduces their oxygen barrier and damages the cuticle. Over time, moisture evaporates from the egg whites through the porous shell and a small air cell begins to form. As an egg ages the air cell slowly expands. 

Eventually, the amount of air within the shell increases to the point that older eggs float to the top of a bowl of cold water and are not longer considered good.

To conduct the float test gently drop a whole egg into a bowl of water.

If the egg sinks quickly to the bottom of the bowl and stays there it is a fresh egg. 

As an egg begins to lose its freshness the wide end of the egg will rest on the bottom of the bowl but top will begin to point upward. These eggs are still ok to eat.

As the air sac further expands eventually the egg floats to the surface of the water. Eggs that float in a bowl of water should be discarded. 

Sniff Test

The sniff test is a simple way to help you learn if an egg is bad. 

A rotten egg has a very distinctive odor. That smell is caused by the presence of hydrogen sulfide, a gas created by the decay of nutrients inside the shell. 

If you suspect your eggs have gone bad simply crack one open and give it a sniff. You will smell the distinctive rotten egg smell immediately. 

Even after cooking or poaching the sulfur smell will not go away. This is a sure sign that they are past their prime. 

Very old eggs will smell like sulfur without even being cracked open. Do not even bother trying to cook a bad egg, or conduct any other tests. Dispose of it, and purchase fresh eggs on your next trip to the grocery store. 

Visual Inspection

You can learn a lot from visually inspecting an egg before you crack open the shell. Begin by checking the outside of the eggshell for cracks or dents. Discard eggs with broken eggshells. Bacteria can enter the egg and cause it to spoil. 

Also, check the shell for powdery spots as this can indicate the presence of mold. And if the shell has a slimy feel that can mean that there is bacteria growing on the eggshell. In both cases discard these eggs (4).

When you crack open your eggs there are other visual signs that to look for that can show you if they are no longer fresh or even if they have gone bad. 

As eggs age, the white or albumen becomes thinner and the yolk becomes flatter. These are signs the eggs are no longer fresh but are still safe to eat. Interestingly, thin, older egg whites whip to a higher volume more easily than fresh egg whites and make better a meringue.

Once you have cracked an egg, check for discoloration of the egg white or the egg yolk. If you notice blue-green, pink, or other off colors, your egg has gone bad. Discard it and wash the bowl carefully. 

Best Way to Store Eggs

Eggs are washed and sanitized soon after being laid to prevent contamination with salmonella, a bacteria often responsible for food poisoning. This process can damage the natural protective coating on eggshells called the cuticle (5). 

Sanitized eggs should be stored in the refrigerator. Cold temperatures prevent bacterial growth and keep any bacteria that may be present on the surface of the shell from moving inside the egg (6).

It is recommended that eggs be stored toward the back of the refrigerator where temperatures stay consistently cold. 

Eggs can also be frozen. It is not recommended to freeze them in the shell. Instead, crack eggs into a freezer-safe container then freeze the liquid. They will last for a year or more when frozen. 

How Long Do Eggs Last?

With proper storage, egg quality will very slowly decline over time. It is generally recommended to eat eggs within 3 to 5 weeks of purchase. 

If you forget when you purchased them and find eggs that are well past the date on the carton, use the methods above to determine if they are still fresh.

Try and keep eggs at room temperature for less than 2 hours. Bacteria that grow on the eggshell can quickly pass inside the egg and make us sick if they are not cooked to a proper temperature.

Health Risks of Eating a Bad Egg

Eggs are still safe to eat even if they are not fresh. Once they are past the expiration date be sure to inspect them, drop them in a bowl of water and sniff them to ensure they are still ok to eat.

The main reason people can get sick from eating a bad egg is foodborne illness caused by salmonella or other bacteria. This bacteria, found not only on eggs but meats, fruits and vegetables can cause diarrhea and stomach pains when consumed. When foods are cooked to the proper temperature these harmful bacteria are killed. 

Egg whites will begin to solidify around 145 degrees, however, egg yolks are not fully cooked until they reach 160 degrees. You should never eat raw eggs unless they have first been pasteurized, a process of heat treatment that kills unwanted bacteria. 

Last Words

A little knowledge gained by using the above tips can save you a lot of time and trouble. At the store, look for eggs with the latest sell-by date, or look for a Julian date closest to the day you are shopping. This will help you purchase the freshest eggs for your omelets or egg salad.

Eggs are still perfectly safe to eat even if it is no longer fresh, based upon the egg carton date or light test. Always do a quick visual inspection of your eggs both at the store and when you are ready to cook with them. Do not use eggs that are off-colored or those with bad odors when they are cracked open. 

If you are not sure about the freshness of your eggs there is always the float test to help determine how much air is in the shell. When in doubt, rely on your senses. Throw questionable eggs away if you are not sure and buy a fresh dozen.

Always cook eggs to the proper temperature before eating them because you cannot see or smell harmful bacteria, even if your eggs have passed all the other tests. 

+ 6 Sources

  1. “What Do the Dates on Egg Cartons Mean?” Incredible Egg, www.incredibleegg.org/cooking-school/faqs/egg-carton-dates. Accessed 29 July 2020.
  2. “Food Product Dating.” USDA, www.fsis.usda.gov/wps/portal/fsis/topics/food-safety-education/get-answers/food-safety-fact-sheets/food-labeling/food-product-dating/food-product-dating. Accessed 27 July 2020.
  3. “Egg Nutrition & Fun Facts.” Incredible Egg, www.incredibleegg.org/egg-nutrition/egg-safety/#5. Accessed 27 July 2020.
  4. “Egg Quality.” University of Florida, www.backyardchickenelearning.com/wp-content/uploads/2013/02/Egg-quality.pdf. Accessed 29 July 2020.
  5. Samiullah. “Effects of Egg Shell Quality and Washing on Salmonella Infantis Penetration.” Int J Food Microbiol, 2013, doi:10.1016/j.ijfoodmicro.2013.05.002.
  6. WHILEY, ALICE, et al. “Higher Storage Temperature Causes Greater Salmonella Enterica Serovar Typhimurium Internal Penetration of Artificially Contaminated, Commercially Available, Washed Free Range Eggs.” Journal of Food Protection, vol. 79, no. 7, 2016, pp. 1247–51. Crossref, doi:10.4315/0362-028x.jfp-16-078.
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