Number 23: Dissolving eggs with washing powder

Biological washing powder contains several types of proteins called enzymes. These are naturally occurring molecules that all living things produce to do particular jobs. They are, if you like, nature’s molecular machines. There are enzymes that digest food, fight infections and replicate DNA. You name a biological process and enzymes are probably involved in it. That’s why the washing powders that contain them are ‘biological’.

The enzymes that are added to washing powders are like molecular scissors that chop up fats, starch and proteins, all of which cause stains on your clothes. The result is cleaner clothes without needing to use hot washes (because the enzymes work at low temperatures).

Its quite easy to see these enzymes in action with a nice simple demonstration using a hard boiled egg.

You'll need

• A hard boiled egg
• 2 or 3 glasses or jars
• A knife
• A teaspoon
• Biological washing powder/liquid
• If you are in the UK you can also buy non-biological washing powder (non-bio is only available in the UK because people here think it causes eczema, it doesn't).

What to do

1) Half fill the glasses with water and then mix in 1 teaspoon of biological washing powder/liquid into the first glass. If you have it add 1 teaspoon of the non-bio powder/liquid into the second glass. And leave the third glass with just water in it.

2) Chop the egg white into small pieces.

3) Place each piece in one of the glasses.

4) Leave the glasses in a warm place (like on a radiator or airing cupboard) overnight.

5) Inspect the bits of egg the next morning.

You should notice that the egg in the water and the non-bio mixture hasn't changed, it still has nice sharp edges where you made the cuts. But the egg in the biological mixture is smaller and the edges are much smoother.

The bits of egg after sitting in the glasses overnight.

What's going on?

One of the enzymes in the washing powder is known as a protease. It's a protein molecule that cuts up other proteins, some of which cause stains. But in this case the egg white, which is mainly protein, gets slowly digested by the protease. The result is a smaller bit of egg white.

I'm a big fan of proteins, they're fabulously intricate, beautiful structures that have evolved the perfect shapes and features required to do their jobs. And so I thought I'd share some of that wonder with you. This is what the protease in your washing powder looks like and (in part) you have it to thank for those nice clean pants.