Why does steamed bread harden after being heated in the microwave oven and then cooled?

The microwave oven uses the principle of magnetic vibration to make the water molecules in the heated object collide with each other to generate heat, but when the temperature is high, the water molecules will evaporate, so the steamed bread can only be heated once, and the second time it will be as hard as stone.

To keep food soft, two elements must be maintained. Humidity and structure. As a microwave treatment, the structure will certainly not change much, but it is easy to harden because it is not locked with water. Therefore, the patent core of the steamed bread toaster also lies in locking moisture.

How to make steamed bread and cake not harden after heating in the microwave oven? Put steamed bread in a covered container and then put it in the microwave oven, which can reduce the loss of water in steamed bread; Or add a small amount of water to the container, so that the steamed bread will be softer after heating, but it should be noted that the cover is still needed.