A Composite Protein
Gluten is a composite protein made up of two storage proteins gliadin and glutenin. It’s found in wheat and closely related grains like barley and rye, in the endosperm of the grain. The endosperm is largely made of starch, and gluten is attached to the starch. It forms a continuous framework around the starch granules. Gluten accounts for 75 to 85% of the total protein content in bread wheat and is insoluble in water.
The storage protein glutenin contributes to the elastic character of gluten while gliadin contributes to extensibility. A balance between elasticity and extensibility is necessary for superior baking performance.
Role of Gluten in Bread making
The gluten found in bread flour is strong and elastic and plays a very crucial and important role in bread making.
It contributes to the ability of the dough to rise and the ability of the dough to maintain its shape as the bread is baked.
Gluten forms when water is added to bread flour and mixed into a dough. As the dough is kneaded it forms a gluten network which contributes to viscosity and elasticity of the dough. If yeast is added to the dough, it ferments and produces carbon dioxide gas which is trapped by the gluten network and this causes the dough to rise. The process of baking coagulates the gluten and together with the starch they stabilize the shape of the bread. Gluten also gives bread its chewy texture. The longer you kneed the bread dough the chewier it becomes because kneading enhances gluten development. Moisture also enhances gluten development and that is why very wet doughs left to rise for a very long time do not require kneading. Check out “The Grants- no knead dough”
Generally, bread flours are milled from hard wheat and are high in gluten. Pastry flours are milled from soft wheat have a lower gluten content.
The addition of a shortening agent like butter or vegetable fat inhibits formation of cross links and if the moisture content is also reduced it results in a flaky product such as a pie crust.
Use of Gluten
Gluten can be extracted, dried and milled to powder. Gluten powder can be added to dough to improve it’s elasticity and ability to rise. The dough must be worked vigorously preferably using a bread machine or electric mixer to induce it to rise to full capacity. Bread flours with higher protein content have more gluten.
Wheat gluten is the basis for imitation meat. When cooked in broth, the gluten absorbs broth and flavour and becomes firm to the bite.
Gluten from wheat, barley or Rye is used as a stabilizing agent in ice cream, salad dressings and ketchup. Barley, may be found in food colouring, malt vinegar and beer; and Rye may be found in beer and cereals. It’s important to read product labels before consuming the product if you are intolerant to gluten.