Bread fermentation means that in the process of making bread, yeast devours the sugar in the dough and converts it into carbon dioxide and alcohol, thus making the dough expand and ferment. The specific principle is as follows:

1. The phagocytosis of sugar by yeast

The yeast added in the bread making process only devours the sugar in the dough and converts it into carbon dioxide and alcohol, thus causing fermentation.

2. Generation of carbon dioxide

After consuming sugar, yeast will decompose it into sugar and produce carbon dioxide through fermentation. A large amount of carbon dioxide will make the dough swell and ferment, resulting in pores.

3. Production of alcohol

Besides carbon dioxide, yeast also produces alcohol. Because of the strong volatility of alcohol, heat energy will evaporate alcohol during baking, making bread taste more diverse.

4. Effect of temperature on fermentation

The optimum growth temperature of yeast is 28-30℃. If the temperature is too high, yeast will die easily and its fermentation capacity will be reduced. If the temperature is too low, the fermentation speed will be slow.

In a word, the principle of bread fermentation is that yeast devours sugar in dough and converts it into carbon dioxide and alcohol, thus making dough expand and ferment.