History

• Saccharomyces cerevisiae has been used by human cultures for thousands of years to leven bread. It is thought that it was first discovered on the skin of grapes and added accidentally to a bread recipe over 5,000 years ago in Egypt. In comparison to the original unleven, dry bread, the finished product took on a flavorful and chewy texture. Louis Pasteur's research in the 1860s led to commercial production of yeast, which has remained a key ingredient in bread baking.
  
  

Production

• Yeast can grow with or without air to support it. The process takes longer in an airless environment. The main energy for yeast comes from sugars; beat and cane molasses are generally used for commercial production. Yeast also requires vitamins, minerals, and salts, which may be added separately during fermentation. Up to 50,000 gallons of yeast may be produced at one time. The process yields from five to eight times the number of yeast cells.
  
  

Function

• Saccharomyces cerevisiae yeast serves three main functions in baking. Yeast produces carbon dioxide by breaking down sugars in the dough. The trapped carbon dioxide causes the dough to expand, or rise. It also causes the dough to mature into an airy and lighter finished product. Yeast provides flavor to the dough as well. While baking, yeast produces ketones, alcohols, and a variety of other compounds. When these react with one another, new flavors are created in the crust and spread to the rest of the bread.
  
  

Benefits

• Yeast is a beneficial fungi. Nutritional yeast provides fifty-two percent of the daily recommended serving protein in just two tablespoons. It is high in Vitamin B, folic acid and fiber. Yeast by itself is gluten-free, so it can be ingested as a supplement for gluten-intolerant. Glucans found in nutritional yeast act as a stimulate to the immune system. Beta glucans can boost the immune system without over-stimulating it. They have been used in treatment of cancer since 1980.