Science gets hard-boiled

QUESTION What is the science behind eggs turning hard when they are boiled? THIS process, unlike other liquids which vaporise, is through denaturation — the breaking of a protein structure by the application of extreme conditions.

Proteins are created by connecting amino acids end to end, then chemical interactions and bonds within the chain cause the proteins to fold into knot-like formations. Each has a unique 3D structure.

Food proteins lose structural shape when an external stressor is applied, as the enzymes won’t work if conditions, such as temperature, aren’t right.

In cooked egg white, the folded chain of amino acids has been shaken apart and entangled with others.

The change from translucent to opaque is due to coagulation — the bonding of proteins into a solid mass.

When proteins denature, the chains become more likely to bond and form a solid network. Water is forced out from between the chains, and a denser association is formed. Coagulation allows us to cook soft or hard-boiled eggs, as the process can be stopped at any time.

But if cooked for too long, the proteins cannot keep water molecules, giving the egg a rubbery texture. Emilie Lamplough, Trowbridge, Wilts. QUESTION Other than Nancy Richey in the Sixties, has any top female tennis player worn shorts, rather than a skirt or a dress? FURTHER to the earlier answer, we saw Martina Navratilova in a ladies’ doubles match at Wimbledon and she was the only one wearing shorts.

She also wore dark underwear. This despite a male player being asked to change into white underwear earlier in the tournament. Maureen and Barry Walker,

Cheadle, Cheshire.