2. Microwave ovens have small fire, medium fire, medium high fire and high fire. If the bread is heated with high fire, it takes about 13 seconds, and it takes about 23 seconds with medium fire. The bread itself has been cooked in the oven, and the moisture content is less than before baking. Generally, freshly baked bread is soft, but with the change of storage time, the softness of bread texture will also change. If you heat the bread, it will harden, indicating that it has been overheated. If you continue to heat it, it will burn and turn into charcoal within 1 minute.