First: too many "flexible materials" (sugar, improver, yeast, oil, etc. ) will cause toast to shrink.

Second: the bread is not ripe. It will also lead to "shrinking the waist."

Thirdly, it may also be caused by incomplete relaxation and excessive fermentation during roll forming.

When the yeast is kneaded into the dough, it will react with the sugar and starch in the dough to produce carbonic acid gas and fragrance, and then the dough will begin to swell after this component enters the gluten network structure film. This process is fermentation. Knead dough is half the battle, and fermentation is the other half of the battle.