How does yeast cause bread to rise?

Yeast is a single-celled microorganism that belongs to the kingdom of fungi. Yeasts are responsible for the process of fermentation, which is the chemical breakdown of sugars into simpler compounds.

In baking, yeast is used to cause dough to rise. This is because when yeast is mixed with water, it starts to feed on the sugars in the flour and breaks them down into carbon dioxide gas and ethanol. The carbon dioxide gas gets trapped in the dough, causing it to expand and rise.

The amount of rise that occurs in dough depends on a number of factors, including the type of yeast used, the temperature of the water, and the amount of sugar in the dough.

There are two main types of yeast used in baking: active dry yeast and instant yeast. Active dry yeast needs to be dissolved in warm water before it can be used, while instant yeast can be added directly to the dough.

The ideal temperature for yeast growth is between 70 and 80 degrees Fahrenheit. If the water is too hot, it will kill the yeast. If the water is too cold, the yeast will not grow well.

The amount of sugar in the dough also affects the rise. The more sugar there is in the dough, the more carbon dioxide gas will be produced and the more the dough will rise.

Once the dough has risen, it is baked in the oven. The heat of the oven kills the yeast and causes the carbon dioxide gas to expand even further, resulting in a light and fluffy loaf of bread.