Yeast Is a Living Fungus
Yeast is a microorganism used in baking and brewing. It is not a chemical but a single-celled fungus.
Yeast is a single-celled fungus used to raise bread and ferment alcohol. It is alive, and that is the whole point: yeast consumes sugar and produces carbon dioxide and alcohol. In bread the gas raises the dough and the alcohol bakes off; in brewing the alcohol is the product and the gas escapes. People used yeast for thousands of years without knowing what it was — Pasteur established in the 1850s that fermentation was caused by living organisms rather than by a chemical process.
- A leavening fungus. *Baker's yeast.*
- Fermentation — what it does. *Fermentation.*
- Saccharomyces — the genus. *Saccharomyces cerevisiae.*
- Pasteur — who explained it. *Louis Pasteur.*
- Old English — *gist*. *The source.*
Word forms
| Form | Word | Example |
|---|---|---|
| Noun | yeast | Yeast. |
| Adjective | yeasty | Yeasty. |
| Verb | ferment | Ferment. |
| Genus | Saccharomyces | Saccharomyces. |
| Old English | gist | Yeast. |
- Add the yeast to warm water.Baking.
- It is a living fungus.Biology.
- Pasteur explained fermentation.Science.
What yeast does
- Consumes sugars in dough or wort
- Produces carbon dioxide, which raises bread
- Produces alcohol, which is the aim in brewing
- Bread's alcohol evaporates during baking
- Beer's carbon dioxide is either vented or kept for fizz
Old English *gist*, of Germanic origin, from a root meaning to foam or seethe.
Is yeast alive?
Yes. It is a single-celled fungus that consumes sugar and produces carbon dioxide and alcohol as it grows.
Who discovered how it works?
Louis Pasteur established in the 1850s that fermentation is caused by living organisms rather than a purely chemical reaction.