Yeast – Why Your Bread Is Fluffy
To make the bread you eat every day, bakers must of course use flour, water and salt, but they also have to add something to make the dough rise. This "something" is usually yeast, a microscopic fungus which gives bread its flavour and lightness.
Bread-making: alcoholic fermentation
1- Mixing all the ingredients, including the yeast known as Saccharomyces cerevisiae
To make yeast breads, microorganisms must be allowed to multiply and exert their effect before baking. To distribute the microorganisms throughout the dough, bakers knead the dough. The most popular bread-making yeast is Saccharomyces cerevisiae.
2- Kneading bread
Kneading gives the dough the necessary consistency, and prevents it from becoming too sticky to be easily shaped.
3- Rising time
The dough is set aside for some time, to allow the yeast to multiply. Yeast digest maltose, the sugar in flour, and transform it into carbon dioxide, which is a harmless gas, and alcohol. Here we can see the effect of allowing the bread to rise: the volume of the dough has increased by a factor of 5!
As the bread bakes, most of the yeast is killed. The alcohol is almost completely burnt off, but leaves behind a pleasant taste.
5- Final result : small gas bubbles are formed in the bread
Carbon dioxide is responsible for the small air bubbles that give bread its light texture.