Staling is the change in texture and aroma of baked goods due to a change of structure and a loss of moisture by the starch granules. Stale baked goods have lost their fresh-baked aroma and are firmer, drier, and more crumbly than fresh products. Prevention of staling is a major concern of the baker, because most baked goods lose quality rapidly.
As indicated, starch retrogradation begins as soon as the item begins to cool. As starch molecules bond with each other, the starch forces out moisture and becomes harder and drier. Even though this moisture may then be absorbed by other ingredients such as sugar, the result is that the texture of the item feels drier. Because this is a chemical reaction of the starch, breads become drier in texture even when tightly wrapped.