Oats, barley, and some breads made from them.
Bread is a popular food in Western society. It is often made from wheat
flour that is allowed to ferment by the addition of liquids and yeast,
and then baked in an oven.
Adding yeast, which is the process of leavening bread, gives it lightness and improves digestibility. But there is also unleavened bread which has important symbolic use in Judaism and is used by some Christian churches.
An alternate technique for leavening bread is the use of baking powder, which typically consists of bicarbonate of soda and rising agents. These are called quick breads and soda breads. Some wheat flours are sold with baking powder mixed in; this is known as self-rising flour. These are also used for cakes and biscuits.
A third technique for preparing leavening bread is known as sourdough. Instead of leavening directly from cultivated baker's yeast, sourdough bread is leavened with a starter. The starter is made of flour, water and wild or cultivated yeasts that is kept in an active state. Only part of the starter is used each time the bread is made and fresh flour and water is added to the starter to keep it active for future use. Similar to the solera system for sherry, this ensures that some of the starter used has fermented for a very long time. The dough is allowed to ferment for a longer period. The starter imparts a slightly sour flavor to the dough (hence the name) and the extended fermentation serves to partly break down the complex carbohydrates in the flour, making the bread more digestible. Sourdough breads have a slightly different texture than conventional yeast breads and are said to keep their freshness longer. San Francisco is known for its really sour sourdough bread. In France, the pain au levain is leavened bread which a far less sour taste than sourdough bread, due to the use of different yeasts.
Owing to its high levels of gluten (which give the dough sponginess and elasticity), wheat is the most common grain used for the preparation of bread, but bread is also made from the flour of rye, barley, maize (or corn), and oats, usually, but not always, in combination with wheat flour.