What happens when you beat egg whites?

What happens when you beat egg whites?

Have you ever wondered what happens when you beat egg whites? Have you ever succeeded in making egg whites? Your chocolate mousse is more a liquid than a mousse?  So this article is for you.

This is the how to make egg whites!

When you beat egg whites, the aim of the operation is to incorporate air bubbles into the egg white. In fact the egg whites is constituted of a water-protein solution. When the  eggs whites are beaten, it creates two kinds of stress in the solution. The first physical effect creates a force which unfolds the protein molecules of the molecule. This process is called denaturation. The second effect is to put these proteins out of their natural state of equilibrium. So they enter in contact with air and water.

The proteins contained in the white egg are composed of amino acids. This kind of molecule has two physical opposite properties. One of the extremities is hydrophobic, that means that is water-fearing. The second extremity is hydrophilic so it’s water-loving. So before the first effect, all the proteins are curled up, the hydrophobic heads are packed in the center away from the water, and all the hydrophilic heads are outside close to the water.  These kinds of molecules are called surface active agents.

So when an egg protein is up against an air bubble, one part of that protein is exposed to air and the second part is still in water.  Indeed the proteins become uncurled, so the hydrophilic part is immersed in the water and the hydrophobic part is in the air. It creates bonds with each other forming a network that can hold the air bubbles in place. It’s called coagulation.

However if you introduce any form of fat, like cooking oils, your egg white will not beat up. Indeed the hydrophobic part will be attracted by the oils and so not by the air.

So if you don’t want your egg white to collapse, you have to stabilize this structure. You can use copper bowl to reinforce the bonds or add cream of tartar, which is an acid and will change the pH and stabilize your foam.

Now that you’re an expert!    Let’s go cooking a chocolate mousse.