Asked by: Anonymous
Staling is often attributed to a simple loss of moisture from bread. But on a microscopic scale, there’s a lot more going on.
The flour used to make bread contains high quantities of starch molecules, which, in their natural state, form a crystalline (i.e. highly organized) structure. Adding water to the flour undoes this structure, allowing the starch molecules to take on a more disorganized, gel-like arrangement that gives bread a soft, fluffy texture when it comes out of the oven.
As bread starts to cool, however, water leaves the starch and moves into other parts of the mixture, allowing starch molecules to return to their crystallized state. It’s this recrystallization – not drying – that makes bread go hard, and it happens even in humid conditions.
So why does bread go hard in the fridge? Recrystallization happens more quickly at cooler temperatures (unless it’s below freezing), so bread will go stale much faster when refrigerated.