Reason 1: poor quality of flour, reason 2: improper mixing, reason 3: the dough is too hard, reason 4: the fermentation time is too long, resulting in the dough is inelastic, reason 5: the shape is too loose.

For toast, the best internal structure should be that there is almost no gap in the cut surface and it feels smooth. But we don't have to pursue this result too much, as long as the pores are small, fine and vertical, and the size is basically the same.

When the dough is not hit to a certain extent, the ductility of the dough is poor and the gas-holding capacity is weak. Some bubbles are easily broken, resulting in large and small bubbles inside, or many small bubbles are broken and connected into large bubbles. At this time, it is usually seen that the dough is full of large and small bubbles when it is set and exhausted.