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.
Medieval cuisine Food preservation methods were basically the same as had been used since antiquity, and did not change much until the invention of canning in the early 19th century. The most common and simplest method was to expose foodstuffs to heat or wind to remove moisture, thereby prolonging the durability if not the flavor of almost any type of food from cereals to meats; the drying of food worked by drastically reducing the activity of various water-dependent microorganisms that cause decay. In warm climates this was mostly achieved by leaving food out in the sun, and in the cooler northern climates by exposure to strong winds (especially common for the preparation of stockfish), or in warm ovens, cellars, attics, and at times even in living quarters. Subjecting food to a number of chemical processes such as smoking, salting, brining, conserving or fermenting also made it keep longer. Most of these methods had the advantage of shorter preparation times and of introducing new flavors. Smoking or salting meat of livestock butchered in autumn was a common household strategy to avoid having to feed more animals than necessary during the lean winter months. Butter tended to be heavily salted (5â€“10%) in order not to spoil. Vegetables, eggs or fish were also often pickled in tightly packed jars, containing brine and acidic liquids (lemon juice, verjuice or vinegar). Another method was to seal the food by cooking it in sugar or honey or fat, in which it was then stored. Microbial modification was also encouraged, however, by a number of methods; grains, fruit and grapes were turned into alcoholic drinks thus killing any pathogens, and milk was fermented and curdled into a multitude of cheeses or buttermilk.[47]