Why does a piece of bread becomes hard when it is left out on table overnight?

A piece of bread becomes hard when left out overnight due to a process called retrogradation. Here's how it works:

* Starch Structure: Bread is primarily made of starch. When dough is baked, the starch granules absorb water and swell, becoming gelatinous. This gives bread its soft and chewy texture.

* Cooling & Crystallization: As bread cools, the starch molecules begin to rearrange themselves. This process is accelerated by lower temperatures. The starch molecules form crystalline structures, which are harder and less flexible than the original gelatinized starch.

* Water Loss: Over time, the bread loses moisture through evaporation. As the water content decreases, the starch crystals become even more tightly packed, leading to a harder texture.

Why it happens overnight:

* Room Temperature: Overnight temperatures are generally cooler than when the bread was first baked, speeding up the retrogradation process.

* Humidity: The humidity in the air also plays a role. Lower humidity levels accelerate water loss from the bread, making it dry out faster.

To prevent this:

* Storage: Store bread in airtight containers or bags to prevent moisture loss.

* Freezing: Freeze bread to slow down the retrogradation process. Thaw it at room temperature or in the refrigerator before consuming.

Let me know if you have any other questions!