How to Test Eggs for Freshness? Testing Eggs for Freshness
Four Simple Tricks to Decide Whether to Keep or Toss
Although there is a date stamped on the side of an egg carton, that isn’t always a good indication of whether the eggs inside are fresh. Some dates are when they were packed (and often written in code) while others are best-buy dates. The American Egg Board recommends eggs be used four to five weeks after they were packed, but we may not always know when that was.1 In addition, if you remove the eggs from the carton when you return from the store, or purchase fresh eggs from a farm, you may be uncertain how old they are.
Luckily, there are three easy ways to determine if your eggs are still safe to eat, and all you need are your senses, a bowl, and some cold water. Keep in mind that if one egg tests bad it doesn’t mean the rest of the eggs should be tossed.
1. The Sink or Float Test
The egg float test has been around for a very long time.
It is a useful and fast way to check if eggs are fresh and safe to eat.
The interesting thing is nobody really knows how it came to be and where this test came from.
Is this test accurate or just a myth?
In this article we will explain everything you need to know about the egg float test including how to perform the test, if it is accurate and much more…
Like a fun science experiment you may have done in school, this freshness test is not only simple but also can tell you the approximate age of the egg. All you need is the egg, a bowl, and cold water. Fill the bowl with enough cold water to completely cover the egg, then gently drop the egg into the bowl of water.
Your egg can do one of three things and each will determine its freshness. If it sinks to the bottom, turns on its side, and stays there, it is very fresh. If the egg sinks but floats at an angle or stands on end, the egg is a bit older (a week to two weeks old) but still okay to eat. If the egg floats, it’s too old and should be discarded. (If you are looking for more of a cut-and-dry test, dissolve 2 tablespoons of salt in 2 cups of cold water. Put the egg in the water—if it sinks, it’s good; if it floats, it’s too old.)
The science behind this is that as eggs age, the shell becomes more porous, allowing air to flow through. The more air entering through the shell, the larger the air cell becomes (the pocket of air between the membrane and shell in the larger end of the egg). The air sac, when large enough, makes the egg float.
How To Do The Egg Float Test
The float test is a quick and simple way to check the freshness of an egg. It will take you about ten minutes to check a carton.
You will need a bowl that is large enough to put an egg in the bottom and be able to cover it with two inches of water.
Now before you start the egg float test you need to check your egg for cracks. There should be no cracks in the shell so discard any cracked eggs before testing.
Step 1: Fill your bowl with 2 inches of cold water.
Step 2: Gently put an egg into the water making sure that you do not drop it in.
Now you need to watch the egg to see how fresh it is.
- Egg stays at the bottom of the bowl and is lying on its side: Very fresh.
- Egg touching the bottom of the bowl but one end is slightly raised: Egg is still fresh.
- Egg stands upright but remains underwater: It is a bit older but still fresh enough to eat.
- Egg floats to the top: The egg is very old and could be rotten – you should throw away this egg.
There you have it – could it be any easier to do?
Is The Egg Float Test Real
Put simply, yes.
The egg float test works and is surprisingly accurate.
People who do this test a lot can tell you with great accuracy how many days old an egg is.
However for our purposes all we need to know is the basics, can we use the eggs or should we toss them? And the egg float test answers this questions with a simple but accurate guide to freshness.
Some folks will tell you that they can sex an egg by floating the egg however this is a myth that is right up there with the shape of the egg and the needle and thread method!
How Does It Work
While the test sounds like magic there are some simple physics and breakdown of organic matter at play.
When an egg is very fresh most of the space inside the shell is taken up with solid matter (yolk and albumin). A fresh egg only has a relatively small air sac at this time. Because of this when the egg is placed in water it will stay submerged because the egg is heavier than the water.
However because eggshells are porous, the older an egg gets the more air will enter the egg.
If you want to learn more about chicken eggs then read how do chickens make eggs? egg laying explained.
Over time the solid matter inside the egg will shrink, this leaves more room inside the egg for air. An egg that is very old will have little content since it will have dried, but it will have lots of air inside the shell.
Once enough air fills the inside of the shell the air will give the egg enough buoyancy to float.
When you place an old egg in the water it will float because it is full of air.
2. The Egg White Test
The second easy method is the plate test.
Simply crack an egg onto a plate and watch how it settles.
This test is a good choice if you plan on cracking the egg before cooking it or adding to a baked good recipe. Crack the egg onto a plate or other flat surface and look closely at the consistency of the egg white—it should be slightly opaque, not spread out too much, and appear thick and somewhat sticky. If it is watery, clear, and runny, the egg has lost its freshness. This is due to the fact that as eggs age, the white turns liquidy and breaks down. You will also notice the yolk will be slightly flat on top instead of rounded.
If the yolk sits bold and upright with a good color and the albumin (white) stays well held together, then your egg is fresh. If the yolk seems tired and slumped and the albumin spreads far and wide then the egg is old. If the egg is bad or rotten you will also be able to do the sniff test. The smell of a rotten egg is unmistakable.
Lastly, some people swear that shaking the egg will tell you how fresh it is.
The science behind this is suspect at best and I really would not rely on this particular test.
3. The Sniff Test
Often when there is a sulfur odor—whether it has to do with eggs or not—it is described as “rotten eggs.” That is because eggs that have gone bad emit a strong sulfur smell. If the egg is really past its prime, you may smell it through the shell; but if not and you’re concerned about freshness, take a whiff after you crack it.
4. Manufacturing Date
Printed Ways To Tell If Eggs Have Gone Bad
There are a couple of other ways to tell how old your egg is.
The easiest is reading carton dates if you buy your eggs from the store. Each carton that the eggs are packed in comes with three pieces of information. These are the packing date, plant number and best by date.
Just keep in mind that the best by date does not mean that the eggs will be rotten, just that they are past their prime.
Manufacturer Dating Decipher
- The long number is the packing plant number.
- This three digit number is the day on which the eggs were packed (January 1st is day #1).
- The last one is the best by date. The eggs should be taken off the shelves by this date.
Whether to Toss or Use
Obviously, if your egg fails any of these tests, you should get rid of it. But if the egg is showing signs of age but not ready for the trash, you can still use it. Older eggs are ideal for hard boiling—since the air cell is larger, there is more space between the shell and the egg, making it easier to peel.
Proper Egg Storage
Eggs should be stored in the refrigerator in the carton they came in.1 The packaging helps keep out odors and flavors from other foods in the fridge and protects the eggs from breakage. Also, you can use the date stamped on the carton as a guide. Make sure to keep the eggs upright, so the larger end is facing up; the yolk is more prone to spoiliage than the white, and this position keeps the air cell at the top, reducing the chances of harmful bacteria from making its way into the yolk. You can also freeze eggs for longer storage.
Other Ways To Store Eggs
Freezing: Freezing eggs is probably the quickest and easiest way to store eggs. Your eggs should be cracked open and now you can choose whether you want the yolks and whites separate or mixed together. Most people mix them up and decant into large ice cube trays for freezing. The larger cube trays hold just about one egg per cube. Eggs preserved like this will keep for about one year in the freezer.
Salt Cure: Salt cured eggs are an acquired taste and a small amount goes a long way so you really should not need many of them. Here is a nice little video on how to salt cure your eggs:
Oiling: This is a quick and simple way to extend the life of your eggs. Using warm mineral oil you should thoroughly coat the egg and place it pointy end up in a clean egg carton. You can keep these eggs in a fridge for up to twelve months. Just remember to turn the carton over once a month just to ensure yolk integrity.
Dehydration: There are several methods to dehydrate eggs but the easiest is the cook/dehydrate method. Scramble your egg in a pan and cook until done. Once they are cooked place them in the oven at 160°F for ten hours. Next you should blend them down to flakes or powder You can now store them in airtight containers.
Water Glass: Eggs preserved using this method can last for up to 12 months! The following video is a really nice clear and concise how to guide:
Egg Cooking Safety
Because salmonella and other pathogenic bacteria are present in most eggs, it is recommended that you should always cook your eggs to well done.2 The bacteria can be inside the shell, so even if you wash the egg or soft-cook it, you could get sick if it’s undercooked. Always cook fried eggs to well done, cook scrambled eggs until they are 165 F, and cook hard-cooked eggs until they are completely firm. And always refrigerate cooked eggs.3 While it’s true that most eggs are not contaminated, if one is, you can get very sick.
If someone in your home has a compromised immune system, is pregnant, or is young or elderly, consider buying pasteurized eggs. (Pasteurized eggs are also good to use in recipes calling for raw eggs, like hollandaise sauce.) These are eggs that have been quickly heated to a temperature high enough to kill bacteria but low enough so the egg remains uncooked. Follow expiration dates to the letter with this product.