Wheat is one of the most widely used grains today, due largely to the fact that it contains gluten. Gluten is a protein that occurs in many grains, but in none so much as in wheat. The high gluten levels in wheat flour give dough made with the flour elasticity. This trait makes wheat flour useful for baking bread, a common staple in many areas of the world.
Production
Gluten consists of two separate proteins found within wheat flour. When the flour is kneaded into a dough, the water molecules within the mixture combine with the proteins gliadin and glutenin, linking them together to form gluten. This molecular bond has both plastic and elastic properties that are useful when producing certain types of baked goods.
Function
Gluten is the protein that helps bread to rise properly. It is highly plastic, which allows the bread dough to stretch without breaking. This action, combined with tiny pockets of carbon dioxide produced by yeast within the dough, allows the bread to rise when baked. As heat expands the carbon dioxide, the pockets blow up within the dough like little balloons. The gluten allows the dough to stretch while the gas expands, creating a light and airy interior.
Protein Levels
Different types of wheat contain different levels of the proteins that produce gluten. Flours from different wheat varieties are often blended together to produce the right protein level for the type of baked goods being made. Pastry and cake flours are typically low in protein, producing finer and less elastic baked goods while breads, pasta and other bakery products that require a lot of gluten use high-protein flours.
Shortening
In some baked goods, however, the gluten in wheat flour can actually interfere with the proper formation and baking of the dough. This is particularly true in pies, in which the crust should be light and flaky, rather than chewy, as in bread. To overcome the elasticity of gluten, a baker adds some type of shortening in the form of butter, lard or hydrogenated vegetable oil to the flour. This interferes with the gluten binding into long molecular chains, thereby "shortening" them and preventing them from becoming tough and elastic.
Celiac Disease
In some individuals, gluten can trigger an autoimmune response that damages the lining of the small intestine, preventing it from absorbing nutrients properly. Symptoms of celiac disease include abdominal pain, gas, bloating, diarrhea, nausea and vomiting, decreased appetite and unexplained weight loss. While the cause is not known, the most common treatment for the disease is to eliminate gluten from the diet completely.
