<P> Staling, or "going stale", is a chemical and physical process in bread and other foods that reduces their palatability . Stale bread is dry and leathery . </P> <P> Staling is not, as is commonly believed, simply a drying - out process due to evaporation . Bread will stale even in a moist environment, and stales most rapidly at temperatures just above freezing . Bread stored in the refrigerator will have increased staling rates, and therefore bread should be kept at room temperature . However, refrigeration delays the growth of mold and extends the shelf life of bread . </P> <P> One important mechanism is the migration of moisture from the starch granules into the interstitial spaces, degelatinizing the starch . The starch amylose and amylopectin molecules realign themselves causing recrystalisation . This results in stale bread's leathery, hard texture . Additionally, pleasant "fresh" flavor is lost to the air, and often unpleasant flavor is absorbed from it as well, especially in a confined space with other food such as when in a refrigerator . </P> <P> Anti-staling agents used in bread include wheat gluten, enzymes, and glycerolipids, mainly monoglycerides and diglycerides . </P>

Why does starchy food like bread become hard and stale when it dries out