Yeasts are the group of the non-mycelial fungi that multiply asexually by budding or fission. The economic importance of yeast is observed in baker's and brewer's industry. Saccharomyces is an outstanding member of Ascomycetes with the ability to convert sugar into carbon dioxide and alcohol by means of enzymes.
In the brewing industry the yeasts like Saccharomyces cerevisiae (Beer or Brewer's yeast) and Saccharomyces ellipsoidens (Wine yeast) are used to ferment sugars during the manufacture of cider, beers, wines, distilled spirits, and industrial alcohols under anaerobic conditions.
In baking industry the kneaded flour is inoculated with Saccharomyces cerevisiae (Baker's yeast). During leavening three types of enzymes are produced. They are amylase, maltase and zymase. Amylase converts starch into maltose, maltase converts maltose into glucose and zymase acts on glucose anaerobically to produce CO2 and alcohol. These two cause swelling or leavening of the dough. The dough is baked, where the CO2 and ethanol is evaporated and makes the dough soft and spongy.