Alcoholic fermentation
Fermentation causes bread dough to rise. Certain yeasts and bacteria are capable of producing energy from sugars through fermentation. Yeast such as S. cerevisiae causes bread dough to rise. - Intro to Biotechnology (Third Edition): Thieman & Palladino
Yeast turns some of the sugar in bread dough into alcohol and carbon dioxide. The carbon dioxide fills the bread with a lot of little bubbles. That makes it easy to eat. Without yeast bread would be like eating raw spaghetti.
Yeast.
Carbon dioxide
Carbon dioxide is the gas produced by yeast cells during fermentation that causes bread dough to rise through the process of leavening. This gas gets trapped in the dough, creating air pockets that expand and make the bread rise.
C02 babe
The yeast feeds on carbohydrates in the dough and produces Carbon dioxide gas, this is what causes all the little bubbles that are present in bread and what causes it to "rise." It is left for a while in order for this process to happen and is usually allowed to double in size. Bread with no yeast in it is called "unleaven Bread."
Yeast added to bread dough produces a gas, and this causes the dough to rise, making the finished bread look like a sponge.
Sourdough bread is sour because of the presence of lactic acid bacteria in the dough. These bacteria ferment the sugars in the flour, producing lactic acid, which gives the bread its tangy flavor. This fermentation process also helps to break down gluten in the dough, making the bread easier to digest.
Retarding is a second, slower rising of your bread dough. It is done by placing the dough in the refrigerator which causes a slower fermentation, or rise, of the dough. Retarding bread dough is often done overnight when the dough is placed in the refrigerator so that it can be freshly baked in the morning. It is also done to increase the flavor of the bread and to give the crust a darker color when baked.
Oxygen is added to bread dough through the process of kneading. When dough is kneaded, the gluten in the flour is formed into a network that traps air bubbles. These air bubbles help the dough rise during fermentation, leading to a light and airy bread texture.
Yes, sourdough bread has a slightly tangy or sour taste due to the fermentation process that creates natural acids in the dough.