Starch in freshly baked good, however, is still in existence in gel form. A product is said to be “fresh” when the starch remains as a gel. When the starch regains its crystalline structure, the product gets firmer and becomes “stale”. In science, this is referred to as starch retrogradation.
Sourdough bread can be light and fluffy. However, as it ages, it becomes hard and dense. Water migration will continue until there are no more water molecules left for the reaction to occur. Bread that has gone stale will have a hard, dry surface.
The process of leavening occurs when the gluten structure or air spaces is filled with a leavening agent, making the dough or batter to rise and expand during baking. Although carbon dioxide is the primary cause of leavening, other gases, such as ammonia gas, water in the form of steam, and integrated air (added during mixing), also contribute to the expansion of baked goods.
Bread takes 5 days or so until it begins to mold. This depends on several factors such as the storage conditions (is it humid and warm?). Bread can last up to 5 days more in the refrigerator. But this is not ideal (unless you are making breadcrumbs) because the temperature is harsh for the starch molecules.
A long time ago, unleavened bread was more common. Unleavened bread is bread prepared without the using of any rising agents, such as yeast or soda. During the ancient times, bread making involved mixing crushed grains and water, and then