Yeasts are a key ingredient in baking bread and fermenting many dishes, but as living things, they don't last forever. Here's how to tell if yours expired.

but from the yeast's point of view, alcohol and carbon dioxide are just waste products. As yeast continues to grow and metabolize sugar, the accumulation of alcohol becomes toxic and eventually ...

In baking, the carbon dioxide from the yeast gets trapped ... too hot and you'll kill the yeast. It should take around 5 to 15 minutes for the yeast to bubble, at which point you can use it ...