Yeast pees alcohol. It farts CO2.
It is highly likely yeast was discovered in the wild on grapes, as part of winemaking. Along came beer and bread. And cultivated yeast.
Yeast is a strange crop.
The crop is a fungus, grown by feeding it sugar, or carbohydrates that become sugar. As a reward, the sugar is turned into alcohol and carbon dioxide. You can use any yeast to make alcohol – and any yeast to make bread!
This is why sourdough works. You’re cultivating the natural yeast found in the flour.
(It is often said you’re capturing yeast from the very air of your environment, but this isn’t really true, but it is a bit more romantic)
Sourdough starter is yeast culture. It hasn’t been selectively bred like store-bought yeast, so it needs longer for the rise to happen.
At the store, there’s plenty of yeast to choose from. Well, there was before the COVID hit and everyone bought all the yeast.
But if there were, you’d have plenty.
Yeast is either slow or fast. It offers two rises or one. Instant Yeast or Active Dry are the two labels most often seen. Instant yeast will usually only need a single rise. Active Dry will need two.
Active Dry is the dough you punch.
This is, of course, a gross simplification.
With yeast, you really want to pay attention to the recipe. If it calls for Instant Yeast, and you use Active Dry, you might run into trouble. In all honestly, sometimes it still works out!
Yeast is a mystery.
I’ve very rarely taken warm water to “proof” the yeast, either. The chances of it not perking up in a bed of warm dough are so small as to be nothing to worry about. Save your minutes!
There are also yeasts that claim to be “better for pizza” or “Bread machine.” In my experience, they are just types of Instant yeast. I am currently using a jar of bread machine yeast because it was all that Meijer had for sale.
Yeasty bread is also a great prank to pull on your friends who insist they don’t like mushrooms.