Plenty of us have eaten meringues made of egg whites. They wouldn't be as popular if they went by their less poetic but more scientifically accurate name: sugared protein foam. Here's how you use chemistry to turn the goo that surrounds the fatty bit of a chicken embryo into a delicious treat.
Step One: Know Your Goo
Inside the goo of an egg white are lots and lots of proteins. The ones we concern ourselves with during this operation are long strands of amino acids which have been curled up into a ball. Also, water is in the egg white. Some of the amino acids in the protein are hydrophobic, meaning they do not mix well with water. They are at the center of the protein ball, surrounded by hydophilic, water-loving amino acids.
Step Two: Add Sugar and Vanilla
This is purely for taste. There's no chemical need for it.
Step Three: Assault the Goo!
Using a whisk, light into that mass of egg white like it's done you a deep, personal wrong. Keep up a fast, steady, circular motion, lifting the whisk clear of the egg white and plunging it back down. The effect of the beating is two-fold. Firstly, it will forcibly unfold the balled-up proteins. Secondly, it will beat air into the entire mixture. When the hydrophobic proteins emerge from their wrapping, they'll naturally migrate towards the air bubbles, away from the water. Once there, they'll lock together. The previously independent strands of protein form a large interconnected network. This will stiffen the mixture. Air will get trapped inside the interlocking segments, puffing the mixture up.
Step Four: Don't Over-Assault the Goo
If you whip the mixture too long, you'll break down the long chains of interlocking proteins. The mixture will soften and collapse.
Step Five: Fossilize the Goo
Put the mixture, either all by itself or in little blobs, into an oven heated to approximately 200°F. The air inside the mixture will heat and expand, puffing the mixture up even more. The heat will solidify the network of protein strands, allowing them to lock the air bubbles in place. The whole thing will solidify into a delicious dessert. Congratulations on your sugared protein foam!
A Final Note: On Acid
Some recipes will ask for something acidic. This isn't to help the egg whites coagulate, but to prevent them from doing so. A little extra acid will keep them from coagulating quickly, so you can beat in more air and make the foam fluffier.