Yeast has been associated with the history of human civilization and culture. It has been employed in
brewing and baking since pre-historic time. Microscopic examination of bread kept with Mummies of
Egyptian Pyramids revealed Yeast cells and thus provide evidence of the use of Yeast about 4000 year
back for bread making.
A. Useful Activities
1. In baking industry: Yeast are used in manufacture of bread. Kneaded flour is mixed with Yeast
and allowed to ferment. Yeast converts starch into sugars and sugar into CO2 and alcohol with
the help of enzyme zymase. CO₂ is released when effervescence takes place due to which bread
become spongy (porous) and gets swollen and is of light weight.
2. In medicines: Because of high content of Vitamins B, B12 and C. yeasts are used for preparation
of digestive tablets.