Leavening

Yeast fermentation helps gluten development because the expansion of air cells by yeast stretches the gluten just as mixing does. After a period of fermentation, the gluten in yeast dough is stronger and more elastic.

While it strengthens gluten, leavening also tenderizes the product. This is because the cell walls become thinner as they are stretched, making the finished product easier to chew.

Too much fermentation, on the other hand, can hurt the gluten structure, because the gluten becomes overstretched. Gluten strands tear and lose their elasticity. Overfermented doughs have poor texture, similar to overmixed dough.