• Question: why do eggs go hard when they are boiled

    Asked by khughes08 to Hermine, Katy, Laura, Nathalie, Paula on 16 Jun 2010 in Categories: .
    • Photo: Paula Salgado

      Paula Salgado answered on 14 Jun 2010:

      Hi there

      Egg whites are mainly made of a protein called albumin. This protein is sensitive to heat, which means that when you heat it, it looses its natural shape or structure and assumes a different, more rigid one. This process is called protein denaturation.

      Basically, when you heat the egg, you are denaturing the albumin in the egg white and that makes the egg white go hard.

      Hope that cleared it for you! 😉

    • Photo: Nathalie Pettorelli

      Nathalie Pettorelli answered on 14 Jun 2010:

      Proteins change properties when they are heated, isn’t it? 🙂

    • Photo: Katy Mee

      Katy Mee answered on 15 Jun 2010:

      Well, i’m sure one of the others can explain this better than me so I’ll just give you a link instead:

      http://recipes.howstuffworks.com/menus/question616.htm

      And the important thing to remember here is that it doesn’t matter why eggs go hard, it’s more important that they DO go hard, otherwise we wouldn’t be able to make cakes!

    • Photo: Hermine Schnetler

      Hermine Schnetler answered on 15 Jun 2010:

      Protein. Eggs are rich in protein. An egg in its natural state has weak bonds holding the proteins in place. When we heat these protein (boil the egg) the bonds are broke apart allowing the proteins to unfold and allows the proteins to make new bonds, stronger bonds, as it does this it forces the liquid (water) that used to surround the proteins, in its natural state, out. Therefore the egg is now hard as there is no longer any liquid.

    • Photo: Laura Dixon

      Laura Dixon answered on 16 Jun 2010:

      Eggs are full of protein and when you heat protein, it changes its structure. So the protein rich liquid inside an egg changes to a solid when the protein is boiled in the water.

Comments