Gluten is a substance made up of the proteins found in wheat flour that gives bread its structure, strength, and texture. Without these marvelous little proteins, bread would not be bread. It also explains why it is so hard to make bread from rice, potato, or oat flour and why wheat flour has to be added to rye flour to make bread—only wheat has enough protein. The gluten makes the bread.
Gluten is developed in the dough when the proteins absorb water and are pulled and stretched in the kneading process. As the proteins are worked, they become long, flexible strands. As the yeast produces gases in the dough, mostly carbon dioxide, these strands trap the gas bubbles and the dough expands. When we put the bread in the oven, the gluten strands coagulate or solidify much as the protein in eggs solidifies as the egg cooks.
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How is it that we can use flour to make both a tender cake and firm chewy French bread? The gluten makes the difference. In a cake, we want little gluten development. In a chewy bread, we want a high percentage of well-developed gluten. We can control this texture in our baked goods by changing four conditions:
1. Selection of flours: Cake flours are “weak” or “soft” and have a low protein content, probably around 8%. Bread flours and high-gluten flours are “strong” and usually have a protein content of 12 to 14%.
2. Amount of shortening: Any fat is referred to as a shortening because it shortens the gluten strands. It does so by lubricating the fibers so they cannot stick together. The more shortening in the dough, the more tender and less chewy the product will be.
3. Amount of liquid: Gluten must have liquid to absorb and expand. If dough does not have enough liquid, the gluten will not fully form and the product will not be tender. That’s why we put a minimal amount of water in pie crusts.
4. Mixing methods: Generally, the more a batter or dough is mixed, the more the gluten develops. Tender muffins use low-protein flour and are mixed only until the moisture is absorbed while breads are kneaded for a relatively long time.