'Egg contain 67 per cent proteins (in egg white) and 33 per cent fats and proteins (in egg yolk). Egg white protein is mostly albumin (ovalbumin and Conalbumin) All proteins have primary,secondary and tertiary structures.

Tertiary structure of egg white protein is due to hydrophobic interactions and hydrogen bonding. They also contain Cysteine amino acid, which has sulfhydryl group (SH).

These sulfhydryl groups form covalent disulfide bonds and hold 2 distant sections of proteins in close proximity. Disruption of the tertiary structure (or 3 dimensional structure) due to heat, chemicals or acidity is called ''denaturation''.

When we heat an egg, the, heat breaks the intermolecular forces and the tertiary structure gets broken. The proteins unfold from their nature folded structure and precipitate forming a white solid mass'

Eggs are rich in protein, especially the egg whites. It's this protein that causes eggs to become hard when boiled. Here's how it works:Protein is a chain of amino acids. These amino-acid strings fold back on themselves (the way the strings fold determines the protein's chemical and biological properties). The proteins are held in place by weak bonds (non-covalent) between different parts of the amino-acid string. When you break those strings, by various methods, you are denaturing the protein.

Eggs are made up something called proteins, actually lots of proteins. When the liquid protein of an egg is heated up, it changes its shape and becomes strong. It then forms a chain with all the other proteins around it. This is what we see as a hard boiled egg.

When you heat an egg, the heat causes the amino acid bonds in the proteins to collapse and rebuild stronger bonds. As this process takes place, the bonds grow stronger and tighter (via energy from the heat) and force out the water that made them liquid. Thus, the equation for an egg is the more you heat it, the more water is forced out during the protein bonding and thus the egg becomes harder.

When you heat an egg, the heat causes the amino acid bonds in the proteins to collapse and rebuild stronger bonds. As this process takes place, the bonds grow stronger and tighter (via energy from the heat) and force out the water that made them liquid. Thus, the equation for an egg is the more you heat it, the more water is forced out during the protein bonding and thus the egg becomes harder.

Heat - When you heat an egg, the proteins gain energy and literally shake apart the bonds between the parts of the amino-acid strings, causing the proteins to unfold. As the temperature increases, the proteins gain enough energy to form new, stronger bonds (covalent) with other protein molecules. When you boil an egg, the heat first breaks (unfolds) the proteins, and then allows the proteins to link to other proteins. As the proteins form these new, strong bonds, the water that surrounded each protein molecule when the egg was liquid is forced out. That's why the egg turns hard. (Heat affects all of the proteins in an egg, so it's the best way to cook an egg.)