why does starchy food like bread become hard and stale when it dries out
Staling 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.
Viscoelasticity When subjected to a step constant stress, viscoelastic materials experience a time-dependent increase in strain. This phenomenon is known as viscoelastic creep.
The Pale The word pale derives ultimately from the Latin word
Fire Once ignited, a chain reaction must take place whereby fires can sustain their own heat by the further release of heat energy in the process of combustion and may propagate, provided there is a continuous supply of an oxidizer and fuel.
Small intestine Food from the stomach is allowed into the duodenum through the pylorus by a muscle called the pyloric sphincter.
Small intestine Absorption of the majority of nutrients takes place in the jejunum, with the following notable exceptions: