How to Check the Freshness of an Egg

Collecting farm fresh eggs from the flock is one of the many reasons why I keep a homestead flock. While I don’t usually have to worry about wondering how fresh an egg is since we go through eggs pretty fast on our homestead, it still helps to have a few tips for checking the freshness of an egg. If you’ve ever found yourself wondering, how old is this egg? Is this egg safe to eat? Then an egg freshness test may be in order! There are several ways you can easily test the freshness of an egg. The four most common egg freshness tests are simple to perform right in the homestead kitchen so you can know how to check the freshness of an egg!

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Why Check Egg Freshness?

Eggs naturally have a pretty long shelf life. If left unwashed, the protective bloom that naturally coats the shell of an egg helps keep bacteria out and keep the egg fresher for longer. Of course, there are various ways to preserve fresh eggs or extend their shelf life, but we won’t go into those methods right now!

Checking the freshness of an egg can be important in these situations:

• Hidden Nest– you found a hidden nest where hens have been laying eggs without you knowing and the eggs haven’t been collected for quite a while
• Counter Eggs– you left eggs out on the counter (which is perfectly fine for unwashed eggs) and you want to see how fresh they are
• Forgotten Carton– you have a carton of eggs that you haven’t dipped into in awhile and are wondering how old the eggs are
• Baking Needs– many baked goods turn out better when fresh eggs are used, so you may want to test the freshness of your eggs when making particular recipes
• Boiling Eggs– while there are ways to successfully boil and peel fresh eggs, sometimes it’s just as easy to boil the oldest eggs in the carton

Like I mentioned before, unwashed eggs naturally have a long shelf life. It would take quite a while for an egg to become un-edible unless it was left in conditions where the egg started to rot. Nonetheless, these egg freshness tests can be helpful to questionable eggs or simply for curiosity’s sake!

The Egg Float Test

The egg float test is a simple egg freshness test you can perform using a glass of water. The float test is based off of the size of an egg’s air cell. Every egg has an air cell located at the blunt end of the egg. The air cell is formed when the contents of the egg cool immediately after being laid. The cooling causes the contents to shrink slightly and form a bubble of air between the eggshell and the inner shell membranes.

In a freshly laid egg, the air cell will be very small. As an egg ages, the contents within the egg shrink even more due to evaporation of the contents through the porous eggshell. The more shrinkage that occurs, the larger the air cell. Since the air cell is full of air, it can cause an egg to float when the egg is placed in water.

How to Perform the Float Test:

1. Fill a clean glass jar or deep bowl with room temperature water.
2. Gently place the egg in the water.
3. See if the sinks, floats slightly, or completely sinks.

The size of the air cell will determine how much the egg floats or sinks, which can then give you a rough estimate of how old the egg is. Here are some general guidelines to use when examining an egg float test:

• sinks completely, flat on its side– fresh
• blunt end is raised slightly but the pointy end still touches the bottom– about 1 week old
• floats vertically near the bottom– about 2-3 weeks old
• floats– very old

While an egg that floats may not be bad, it is probably past the point of being desirable to eat. If you want to test the floating egg further, you can try some of the other egg freshness tests on it!

Candling Eggs

Candling eggs is the method of holding an egg up against a bright light in a dark room. The light will shine through the shell and illuminate the contents. Candling is a practice used when incubating eggs to check on embryo development. However, it can also be helpful for seeing inside an egg to check for freshness.

How to Candle an Egg:

1. Get a very bright, strong flashlight. Preferably one with a narrow lighted end so that it is not bigger than the circumference of the egg.
2. Go to a dark location. A windowless room or closet works well.
3. Turn the flashlight on and hold the egg up to the light. It helps to hold the egg at an angle so that the light is shining at the blunt end of the egg but not directly at the air cell, which could block the light from illuminating the rest of the egg. Holding the egg upright (pointy end up) and at an angle is often the easiest way to see inside the egg.
4. Examine the contents of the egg and the size of the air cell. You can use an egg air cell chart to get a better idea of what the size of the air cell indicates as far as age goes.

Eggs that have a light eggshell color will be easier to see inside of compared to eggs with a dark eggshell color. When you illuminate the egg, you will be able to see the air cell and the yolk floating within the albumen. You may also be able to see hairline cracks in the eggshell, blood or meat spots in the egg, and double yolks. The yolk inside the egg will look like a dark, fuzzy blob that moves slightly when you move the egg.

Here is how candling can give you hints at how fresh an egg is:

• Old Eggs– The yolk can be seen more clearly as the albumen (whites) have thinned out due to evaporation. The yolk will also move more freely when the egg is spun due to the thinness of the albumen. An old egg will have a large air cell.
• Fresh Eggs– The yolk will be a vague, fuzzy, dark blob near the center of the egg. It will move minimally when the egg is spun. A fresh egg will have a thick albumen to hold the yolk in place and it will have a small air cell. A fresh egg will have an air cell that is no more than 1/8th of an inch.

How quickly an egg ages (and how quickly the air cell increases in size) will depend on how the egg is stored and the density of the eggshell. Thin shelled eggs will age faster than thick shelled eggs. Storage conditions such as temperature and humidity will also play a role in how fresh an egg stays.

Temperature can help preserve freshness while humidity can help reduce evaporation. Not washing fresh eggs can also help prolong their freshness.

Egg Bowl Test

The egg bowl test requires that you break open the egg in question to examine the contents. The egg bowl test can be done after performing a float test or candling the egg if desired. When checking an egg’s freshness using the bowl test, you are relying on your observation skills to see changes in the egg’s yolk and albumen (whites).

How to Perform a Bowl Test:

1. Get a clean, shallow bowl that preferable doesn’t have any coloring or designs on it.
2. Crack the egg into the bowl.
3. Examine the egg yolk and albumen.

A fresh egg will have two layers to the albumen. A thick, somewhat cloudy portion of the albumen will directly surround and support the egg yolk. Around the thick portion of the albumen will be a somewhat thinner portion of the albumen. The yolk of a fresh egg will also be nice and round, full, and less likely to break when you crack open the egg. All this is because the egg is fresh and the contents have not had time to evaporate and thin down.

In an old egg, the albumen will not exhibit the two distinct albumen layers as clearly. The albumen may appear thin, flat, and clear. The yolk in an old egg will also appear more flat and will be more fragile, it may even break when you break open the egg. This is because the contents of the egg have started evaporating. Moisture from the albumen has also started moving into the yolk membrane, which stretches the yolk membrane and makes it weaker.

Even though an egg may have a thin albumen and a flat yolk, the egg is usually still safe to eat as long as it doesn’t smell.

What’s That!?

When doing the egg bowl freshness test, you may also find some other interesting additions. A few interesting additions you might notice in some eggs are blood or meat spots. Both blood and meat spots can occur accidentally when an egg is being formed in a hen’s reproductive tract. A blood spot happens when a spot of blood accidentally gets enclosed with the egg.

Meat spots occur when a portion of the reproductive tract lining gets shed and accidentally enclosed within the egg. Both blood and spots are fine to eat, however, they certainly don’t look too appetizing! Blood spots, meat spots, nor double yolks indicate anything about the freshness of an egg.

Egg Sensory Test

The last egg freshness that you can perform is the sensory test. The sensory test is an old-fashioned method of using your senses of smell, sight, and hearing to get a gauge on the freshness of an egg. Performing the egg sensory test is similar to the bowl test, however, you don’t have to crack the egg open.

For the egg sensory test, pick up the egg in question and evaluate is based on these senses.

What to Look for in a Sensory Test:

• Smell the Egg– if the egg smells rotten or has a sulphury odor than the egg is bad
• Examine the Eggshell– if you see stuff oozing from the eggshell, then the contents of the egg are rotting and starting to build pressure within the egg (Note: cold eggs will condensate when they are removed from the fridge)
• Shake the Egg– older eggs will make more of a jostling, sloshing noise when you shake the egg since the albumen is thinner and the contents can move more freely

The sensory test is a great way to quickly identify an egg that has gone bad and is un-edible!

What to Do With Old Eggs

Obviously rotten or spoiled eggs are un-edible, both for you and your flock. However, if an egg is not visible (give it a smell too!) rotten or spoiled, then more than likely the egg is still safe to eat. Sometimes older eggs look unappetizing to us, but your flock or other homestead animals may enjoy an old egg!

Here are some guidelines for dealing with old eggs:

• rotten/spoiled eggs– throw away, compost, bury
• 1 to 2 weeks old– still edible and appetizing (may depend on storage method), good for boiling
• 3 to 4 weeks old– still edible, probably looking a little less appetizing, good for boiling
• 4+ weeks old– may want to feed them to your chickens, dogs, or other homestead livestock animals that benefit from eggs in their diet

In regards to composting, yes, you can put raw eggs in your compost. If the egg is spoiled or rotten, you may want to bury the egg to prevent your chickens or other animals from consuming the bad egg.

Whether you’ve found that hidden nest of eggs on the homestead, or you just realized you had a forgotten carton of eggs in the fridge, these egg freshness tests should help answer questions in regards to the freshness of any questionable eggs. These tests are also just fun to do for curiosity’s sake! When competing in a National 4-H Egg Grading competition, I had fun trying to gauge the freshness and quality of production eggs. Eggs from the homestead flock are as fresh as you can get though!

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by Alexa