What role does gluten play in bread making?

Gluten is a protein. Bread flour does not contain large amounts of protein (approx. between 10.5 – 13%) but it is very important for the bread making process. When flour is mixed with water, the gluten swells to form a continuous network of fine strands. This network forms the structure of bread dough and makes it elastic and extensible.

Kneading/High Speed mixing in bakeries

• The addition of water to flour causes hydration of the Gliadin and Glutenin proteins and leads to the formation of gluten.
• This stage “works” the dough, stretching the gluten complexes.
• Stress induced by mixing breaks bonds between protein chains, allowing the chains to move and become realigned. The new bonds that are formed allow relaxation of the dough.
• Gluten strengthening (or oxidising) agents, such as, ascorbic acid stimulate the formation of these new bonds, strengthening the dough structure.

Proofing (Rising)

• At this stage starch breakdown and fermentation occur.
• As bread dough ferments and proves, the yeast produces carbon dioxide gas that causes the gluten network to expand.
• This leaves an open cellular structure with the gasses trapped in pockets.

The quality of gluten in dough is very important:

• If gluten is too weak it can’t stretch in thin films around the air bubbles produced during fermentation.
• The gas bubbles would then swell and burst, causing the loaf to lack volume.
• If gluten is too strong then it won’t stretch so the gas bubbles can’t expand causing a very dense loaf.

A model which can be used to explain the mixing and proofing stages is the action of bubble gum. Firstly the gum is hydrated in the mouth by saliva then mixed and softened by chewing until it forms an elastic mass. This is then able to expand and support an air bubble.

Baking

• As bread bakes, the gluten protein coagulates.
• This sets the gluten so that it is no longer elastic and determines the bread size and shape. This change does not reverse when bread is cooled.
• The end result after removal from the oven and cooling, should be a firm but open and light textured loaf of bread.