Why do cakes and biscuits go soft when they are stale?

Cakes and biscuits go soft when they are stale due to a process called retrogradation. Retrogradation is the recrystallization of starch molecules over time, which causes them to become more ordered and lose their moisture. This process is accelerated by exposure to air, heat, and light, which is why cakes and biscuits that have been left out or stored improperly will go stale more quickly.

When cakes and biscuits are first baked, the starch molecules are in a disordered, amorphous state. This allows them to absorb water and form a gel, which gives the cake or biscuit its structure and texture. However, over time, the starch molecules will begin to recrystallize into a more ordered, crystalline state. This process causes the gel to break down and the cake or biscuit to become dry and crumbly.

In addition to retrogradation, other factors can also contribute to the staleness of cakes and biscuits. These include the loss of moisture through evaporation, the oxidation of fats and oils, and the growth of mold and bacteria.

Here are some tips to prevent cakes and biscuits from going stale:

* Store cakes and biscuits in an airtight container at room temperature.

* Avoid exposing cakes and biscuits to heat, light, and air.

* If you want to store cakes or biscuits for a longer period of time, you can freeze them.

* When you are ready to eat a stale cake or biscuit, you can try refreshing it by heating it in the oven or microwave for a few seconds.