dough from the previous day to use as a form of sourdough starter, as Pliny also reported. The ancient Egyptians, Greeks, and Romans all considered the degree of refinement in the bakery arts as a sign of civilization. The Chorleywood bread process was developed in 1961; it uses the intense mechanical working of dough to dramatically reduce the fermentation period and the time taken to produce a loaf. The process, whose high-energy mixing allows for the use of grain with a lower protein content, is now widely used around the world in large factories. As a result, bread can be produced very quickly and at low costs to the manufacturer and the consumer. However, there has been some criticism of the effect on nutritional value. Types Bread is the staple food of the Middle East, Central Asia, North Africa, Europe, and in European-derived cultures such as those in the Americas, Australia, and Southern Africa. This is in contrast to parts of South and East Asia, where rice or noodles are the staple. Bread is usually made from a wheat-flour dough that is cultured with yeast, allowed to rise, and finally baked in an oven. The addition of yeast to the bread explains the air pockets commonly found in bread. Owing to its high levels of gluten (which give the dough sponginess and elasticity), common or bread wheat is the most common grain used for the preparation of bread, which makes the largest single contribution to the world's food supply of any food. Bread is also made from the flour of other wheat species (including spelt, emmer, einkorn and kamut). Non-wheat cereals including rye, barley, maize (corn), oats, sorghum, millet and rice have been used to make bread, but, with the exception of rye, usually in combination with wheat flour as they have less gluten. Gluten-free breads are made using flours from a variety of ingredients such as almonds, rice, sorghum, corn, legumes such as beans, and tubers such as cassava. Since these foods lack gluten, dough made from them may not hold its shape as the loaves rise, and their crumb may be dense with little aeration. Additives such as xanthan gum, guar gum, hydroxypropyl methylcellulose (HPMC), corn starch, or eggs are used to compensate for the lack of gluten. Properties Physical-chemical composition In wheat, phenolic compounds are mainly found in hulls in the form of insoluble bound ferulic acid,