Definition

• Fermentation refers to the controlled decay of material, usually in food products, resulting in a more desirable product. Fermentation occurs when bacteria and enzymes convert sugars, carbohydrates and starches into alcohol and organic acids through a biochemical reaction.
  
  

How It Starts

• For fermentation to occur, bacteria and enzymes must be introduced into the material that is supposed to ferment. This usually involves using a starter culture. This starter culture includes certain bacteria that are preferred for fermentation of a specific material. A sample from previously fermented foods or a commercial fermentation mixture can be the starter culture. Some materials need special conditions to cause fermentation to occur properly.
  
  

Preservation of Food

• Bacteria used in fermentation inhibit the growth of other bacteria, which cause food to spoil, causing food to undergo less deterioration. In some fermentation processes, the acidity of the fermenting food is raised, preventing harmful microorganisms in the food. In other fermentation processes, good bacteria are encouraged to grow, which fights off bad microbes in the fermenting food. Depending on what fermenting process was used, food can often be consumed years after it was fermented.
  
  

Rising Bread

• Although fermentation is most often used to preserve food, it can also raise bread and dough. Yeast, which serves as the starter culture, eats the sugar in the fermenting material, causing carbon-dioxide gas to be released. The release of carbon-dioxide is what causes the dough to rise and double in size.
  
  

Creating New Flavors

• The fermentation process creates new flavors through the biochemical reaction. You can also change flavors in fermenting food by adding herbs and spices during the fermenting process. This is the case when turning cucumbers into pickles.