Are Eggs Liquid or Solid and Why Do They Change State When Heated?

[STEMucator]

So while i was cooking my eggs this morning for breakfast, some interesting questions dawned on me.

Are eggs a liquid or a solid and more interestingly, why do they become a solid when they are heated up?

If eggs are a liquid, why don't they change into a gas? If they are a solid why don't they change into a liquid?

 

[Enigman]

An overview:


Molecular level (video):
http://highered.mcgraw-hill.com/sit...chapter2/animation__protein_denaturation.html

and wiki: Denaturation (like your boiling eggs)

Background
Proteins are amino acid polymers. A protein is created by ribosomes that "read" RNA that is encoded by codons in the gene and assemble the requisite amino acid combination from the genetic instruction, in a process known as translation. The newly created protein strand then undergoes posttranslational modification, in which additional atoms or molecules are added, for example copper, zinc, or iron. Once this post-translational modification process has been completed, the protein begins to fold (sometimes spontaneously and sometimes with enzymatic assistance), curling up on itself so that hydrophobic elements of the protein are buried deep inside the structure and hydrophilic elements end up on the outside. The final shape of a protein determines how it interacts with its environment.
When a protein is denatured, secondary and tertiary structures are altered but the peptide bonds of the primary structure between the amino acids are left intact. Since all structural levels of the protein determines its function, the protein can no longer perform its function once it has been denatured. This is in contrast to intrinsically unstructured proteins, which are unfolded in their native state, but still functionally active.

http://en.wikipedia.org/wiki/Denatu...uration_occurs_at_levels_of_protein_structure

 

[STEMucator]

Hmm so proteins form a helix due to hydrogen bonding among other things.

So when the proteins are denatured, they form a solid state by bonding with $H_2O$ molecules.

This is some really interesting stuff. I never knew eggs were so complicated (relatively). When I first thought about it I was like "oh no! a contradiction to the KMT", but now I see how it works.

Thank you for providing that very informative video :)

 

[Enigman]

Hmm so proteins form a helix due to hydrogen bonding among other things.

There are two types of secondary structure:
α-Helix and β-pleated sheet:

The different levels of structures are:

 

[LudusRex]

I find your questions about eggs to be very intriguing. The answer to whether eggs are a liquid or a solid is not as straightforward as one might think. Eggs are actually a combination of both liquid and solid components. The egg white is mostly liquid, while the yolk is more solid.

The reason eggs become solid when heated is due to the proteins in the egg whites and yolks denaturing, or changing their structure, when exposed to heat. This denaturation causes the proteins to unfold and form a solid network, giving the egg its solid consistency.

As for why eggs do not change into a gas when heated, it is because the boiling point of eggs is much higher than the temperature at which they are typically cooked. Additionally, the eggshell acts as a barrier, preventing the eggs from evaporating.

Similarly, eggs do not change into a liquid when cooled because their melting point is much higher than room temperature. The solid structure formed by the denatured proteins remains intact even when the egg cools down.

Overall, the unique composition of eggs and the properties of their components allow them to maintain their solid form when heated and cooled. I hope this explanation has satisfied your curiosity about eggs and their interesting behavior when exposed to heat.