Why do fresh eggs sink and rotten ones float?

Caution with eggs must be observed throughout the year, but especially in summer. Foods made with raw eggs, such as mayonnaise, can be a breeding ground for germs such as salmonella. This can happen due to poor preservation, even if we used the freshest eggs. But, logically, the situation is even worse if we used spoiled eggs. Therefore, it is worth identifying them before using them. The trick is very famous put a raw egg in water and see what happens. If it sinks, then it is fresh. If it pops up, we have to get rid of it, even if we were going to cook it. But why is this?

The reason is in natural decomposition processn what happens in eggs over time. It is often said that this is because they are filled with gas, but this is not an accurate answer. True gas interferes with the process, but does not remain inside the shellbut it comes out.

In fact, if the gas hadn’t come out eggs don’t swim and we could not have that curious indicator of its freshness. So let’s see what happens, let’s start by finding out what the essential physical quantity in this process consists of: density.

What does gravity have to do with egg freshness?

Roughly speaking, for one substance to float on top of another, it must be less dense. For example, if the ball is cork floats on water because it is less dense than it is. Instead, a ball of become it sinks because it has a higher density.

Density is calculated dividing body weight by volume. In the above case, the two balls can be identical to the eye, with the same volume. However, steel is much heavier than cork, so there will be much more mass in the same volume and therefore a higher density.

In the case of eggs when they are fresh they sinkbecause its density is greater than that of water. On the other hand, when they lose that freshness and are in a bad state to eat, they float. This suggests that its density has decreased.

It is often said that this is because when the albumen and yolk decompose, partly due to the action of microorganisms, a gas is formed. And this is true, but this gas does not remain inside the egg. In fact, if this were the case, the eggs would not float for two reasons. On the one hand, because its volume does not change. hard shellso they cannot inflate like a balloon. And, on the other hand, because the masses of protein and yolk will be the same, whether they are in a liquid state or in a gaseous state. If we have the same mass and the same volume, the density will not change.

But it turns out porous egg shell. This is one of the reasons why they get dirty so easily and are so sensitive to temperature changes. And that’s also the reason why some of these gases can escape. Thus, although the volume of the egg is preserved, its mass is reduced and, therefore, we have a lower density. This density decreases until it is below the density of water, and that is when it floats.

So yes, eggs float because of the gas that forms in them when they are stale. But not because it accumulates, but because it goes abroad. However, you know if it floats, don’t eat it. Your health will thank you.