Question

How does yeast cause bread to rise?

Answer 1

Hint : The yeast is added to dough along with the sugar and lukewarm water. This helps the yeast to carry out a metabolic process which produces carbon dioxide. This carbon dioxide helps in raising the dough making it soft.

Complete Step By Step Answer:
To solve this question, we must know about the fermentation in yeast.
The fermentation is a chemical process which involves breakdown of carbohydrate or sugar by the help enzymes in the absence of oxygen. The carbohydrate is converted into ethanol and carbon dioxide.
Yeast is a single celled eukaryotic organism which belongs to the fungus family. Under optimum conditions, yeast grow and reproduce very quickly. The bakers use Saccharomyces Cerevisiae which is also known as sugar eating yeast as it has the capacity to undergo fermentation.
Yeast is added to the dough along with the warm water and sugar. The yeast becomes metabolically active in warm conditions. This activated yeast metabolises the sugar in the absence of air and produces ethyl alcohol and carbon dioxide. This carbon dioxide gas generates a network of air bubbles causing the bread to rise. The yeast starts its replication and multiplies. This produces more carbon dioxide.
Uses of yeast:
-Yeast is used in the bread and baking industry as a leavening agent.
-It is used for the preparation of ethanol.
-Yeast is also used for making cheese.

Note :
Fermentation is a very old process which is widely used in the food and beverage industries. This process converts the fruit juices into wine. It is also used for preserving and flavouring vegetables and dairy products. Through this process antioxidants, vitamins and essential amino acids are enriched in food.