The yeasts have a lot of economic value to the mankind. They have certain beneficial as well as harmful activities.
1. Bread Making:
For the manufacture of bread, yeast is mixed with white flour. Blocks of treated flour are kept at suitable temperature. The process of fermentation starts. Ethyl alcohol and carbon dioxide are formed. The bread swells up and becomes spongy due to the pressure exerted by accumulated carbon dioxide. Flavor and quality of bread is attained by selecting different strains of yeast.
2. Production of alcohol:
Ethyl alcohol is manufactured by the fermentation of potatoes, cereals, molasses etc.
C6H1206 + Yeast zymase > 2C2H5OH + 2C02
(Glucose) Fermentation (ethyl alcohol) + (carbon dioxide)
The breakdown of carbohydrates (starch and sugar) by yeast into carbon dioxide and ethyl alcohol in the absence of oxygen is called alcoholic fermentation. The alcohol is the major ingredient in brewing industry.
3. Yeast as a source of food:
Yeast contains nutritive substances and proteins in sufficient quantities. Dried yeast cells contain 40 – 50% of protein. Some strains of yeast have considerable amount of fat.
4. Yeast as a source of Vitamins and enzymes:
Yeast is used in the preparation of Vitamin – B complex tablets. When yeast cells are irradiated with ultra-violet rays, Vitamin – D is produced. They are also utilized in medicine as a source of enzymes.