SCIENTISTS believe they've solved the puzzle of how chicken eggs are strong enough to break from the outside, but weak enough to be broken from the inside when the chick hatches.
A Canadian study found that egg shells develop as strong, but not too weak, due to changes in their nanostructure that occur during egg incubation.
Researchers believe that a better understanding of the events that fuel eggshell hardening and firmness could have important food safety implications.
The McGill University team in Montreal used new techniques to expose the interior of the egg shells and study their molecular nanostructure and mechanical properties.
You said that birds have benefited millions of years of evolution to make the perfect eggshell ̵
Eggs are sufficiently hard to lay and incubate to protect them from breakage. When the chick grows in the eggshell, it needs calcium to form its bones.
During egg incubation, the inner part of the shell dissolves to provide this mineral ion pool, while at the same time weakening the shell to such an extent that it can be broken by the brooding chick.
Using atomic force microscopy and electron and X-ray imaging techniques, the team found that this dual-function relationship is possible thanks to tiny changes in the shell's nanostructure that occur during egg incubation.
In parallel, the researchers succeeded in replicating a similar nanostructure by adding the mineral crystals, osteopontin, grown in the laboratory.
They found that one factor that determines shell strength is the presence of nanostructured mineral in association with osteopontin, an eggshell protein that also occurs in biological composites such as bone.