Why don't you use egg yolk in meringue?

There are two parts to today's activity. First you're going to discover how meringue is made. Can you believe it starts out as egg whites and sugar?? Do you know why egg yolk isn't used to make meringue just the white?

Once you've made delicious meringue pieces, you're going to build delicious meringue, cream and strawberry towers.

Build meringue towers - fun kitchen science for kids — Image taken from **Snackable Science**

Did you know egg whites are 90% water? and about 10% protein.

Proteins are made up of amino acids. Some amino acids are are attracted to water while others are repelled. When you whisk the egg white mixture you add air to it. The amino acids which are repelled by water attach to the air. The more you whisk or beat the mixture the more amino acid covered bubbles you create, making the mixture fluff up. The sugar acts as a stabiliser helping the amino acids bond together.

Question: Why don't you use egg yolk in meringue?

Egg yolks contain fat which interferes with how the proteins arrange themselves, stopping the mixture fluffing up.

Meringue Ingredients

4 egg whites

200g caster sugar

Bowl - not plastic as these tend to retain oils which might interfere with the mixture

Electric whisk

Spoon

Parchment paper

How to make Meringue

Pre-heat the oven to 110 degrees, gas mark 1.
Line 2 baking sheets with parchment
Put the egg whites in a bowl and whisk slowly at first then faster as they expand. Once you get stiff peaks the egg whites are ready.

egg white ready to make meringue. Why don't you use egg yolk in meringue

Add the sugar slowly a few tablespoons at a time and whisk after each sugar addition
Place 2 heaped tablespoons of mixture onto the baking parchment, leave a gap and then repeat until all your mixture is used up.
Place in the oven for about an hour and leave to cool.