Question

On boiling an egg, why does the outer part become opaque and white?

• A. The heat causes a reaction of the egg with water and makes it opaque.
• B. The heat causes a change in the crystal structure of egg yolk.
• C. The heat causes a change in the structure of egg protein.
• D. The heat causes denaturation, hardening the albumin and colouring it opaque white

Answer 1

Answer:

D. The heat causes denaturation, hardening the albumin and colouring it opaque white

Protein Denaturation and Egg Cooking

• The white part of an egg is primarily composed of albumin, a protein.
• When an egg is boiled, the heat energy causes the protein molecules in the albumin to undergo a process called denaturation.
• Denaturation involves the unfolding of the complex, coiled protein structures into simpler, extended chains.
• These unfolded protein chains then interact with each other, forming a three-dimensional network.
• This network traps water and creates a solid, opaque structure.
• The original clear and translucent appearance of the egg white transforms into a firm, opaque white colour due to this protein aggregation.
• This phenomenon is a classic example of how heat affects protein structure and is a fundamental concept in food science and chemistry.
• The yolk also undergoes denaturation, but it contains different proteins and fats, resulting in a different texture and colour change.