Question

I found in a book from 1500's that says that when you cook an egg (I assume a raw egg), it will get softer before it gets harder. Is that accepted by the science community today? Can someone explain to me how this is?

Answer 1

The softening of an egg before it hardens during cooking is due to the denaturation and coagulation of proteins. The albumin proteins in egg whites initially unwind when heated, then aggregate into a solid state as the temperature exceeds 373 K, making this process irreversible and resulting in a hard-cooked egg.

Step-by-step explanation:

Yes, the observation from the 1500s that an egg will get softer before it gets harder during cooking is accepted by the science community today. This phenomenon is explained by the denaturation and coagulation of proteins, specifically albumin found in egg whites.

Initially, as the egg heats up, the tightly packed albumin proteins begin to unravel, breaking the hydrogen bonds and resulting in a more fluid state.

However, as the temperature increases to greater than 373 K (100°C or 212°F), the proteins continue to denature and then begin to aggregate into a disorganized solid, causing the egg white to become firm and opaque.

This process, marked by a positive change in entropy (ΔS > 0), is spontaneous and irreversible at these high temperatures as the free energy of the system decreases (ΔG < 0).

When an egg is fried, this denaturation process is easily observable; the clear egg white becomes solid and opaque.

It's important to note that the structure of these proteins is based on their amino acid sequence, and under the right conditions, it's possible for denatured proteins to refold and regain biological activity—however, this does not apply to cooked eggs, where the process is not reversible.