I have made bread with a toaster several times. The first two breads were very successful! But the later, the more ... the characteristics of early bread: 1. It has been in the fermentation stage for a long time, but the dough always won't rise. The baking time was over, but the bread didn't swell. When the bread is cut (to be exact, it should be torn), it has a strong sour taste and can hardly be eaten. After making bread like that a few times ago, our family immediately took action to find the root of the problem. The final conclusion is that when making bread, we often open the lid of the bread machine because of curiosity, which leads to the failure of bread; Or because the degree of yeast fermentation is not enough, or there is too little baking powder. But the last time I made bread, I chose a new baking powder, and the amount met the specifications. After putting the materials into the toaster, we never opened the lid from beginning to end. But this time the bread is still not full (but much better than before), and the middle of the bread is still a little sour. Why? (The toaster is aca)