The Water Float Test for Eggs – How to tell if they’re fresh
The Egg freshness Test in Water is used to test whether your eggs are good or bad to use. Some people say “do bad eggs float”. In this post we will answer this question.
So, you’ve got a carton of eggs in the fridge that has gone well past its sell-by date. Now what? All is not lost, as the printed date on the packaging doesn’t actually correspond to an expiration date.
You might have your awesome egg cooker in your kitchen ready to go, but you’re unsure of what to do.
Contrary to popular belief, when it comes to an egg’s freshness, the nose doesn’t always know. And, you can’t rely solely on your eyes and the “best by” date to determine if an egg is still good enough to eat.
So you might be asking yourself how do I check whether my eggs are fresh. A well established and reliable method used by all manner of cooks is the float test.
So what equipment do you need to have to complete the float test? Quite simply a glass and some water, that’s all. No fancy equipment needed at all.
Sink or Swim
The best kept secret in determining an egg’s freshness is to see if it sinks in water. To try the egg water test, simply fill a glass or bowl with cold water and submerge the eggs.
If the eggs sink to the bottom and lay flat on their side, they’re still fresh. However, if they sink, but stand on one end at the bottom of the glass or bowl, they’re not as fresh but still edible.
Of course, if any eggs float to the top, they shouldn’t be eaten. The science behind this is based on the fact that eggshells are semipermeable, which means air can get through.
So the older the egg, the more air can penetrate its shell, causing it to float.
- Fill the large glass with water to the top.
- Then get you eggs one by one and place them in the glass full of water.
- What you will soon notice is that some eggs will rest at the bottom of the glass in a horizontal position, some will rest towards the bottom in a more vertical position and finally some may float towards the top of the glass of water in a more vertical position.
Grouping Good and Bad Eggs
As you complete the test start to group the eggs into those that float, those that sink and are slightly vertical and those that sink and lie horizontally on the bottom of the glass during the float test.
The eggs that sink and settle at the bottom of the glass in a horizontal position are the freshest eggs whilst those that float to the top of the glass are bad.
The group of eggs that sinks to the bottom of the glass but lie in a more vertical position are still good to eat but are less fresher and need to be eaten as soon as possible.
So the answer to the question “do good eggs float or sink” is that the freshest of eggs will sink to the bottom.
Science behind the Float Test
You might be asking yourself why some eggs float in water and others sink. Here’s the science behind the egg freshness test in water. It’s all down to air pockets being present in the egg. When a bird lays an egg at its freshest point the egg will have in most cases a very small air pocket or none at all.
This means that the fresher an egg the more likely it is to sink as there is not enough air on the egg to keep it afloat.
As the egg begins to age both moisture and gases within the egg will seep through the egg’s porous shell. So as it ages more of this moisture will leave, which in turn provides more space for air to enter the egg.
This process ensures that the air pocket grows and grows. So in bad eggs this air pocket will be large enough to allow the eggs to float in water.t
So when you’re ready to cook or boil your eggs whether you use an electric egg cooker or a pan of boiling water use the float test to ensure you only use the freshest eggs.