quick-rise yeast, rapid-rise yeast
Yeast, a living mircoscopic organism, is the driving force behind fermentation—the magical process that allows a dense mass of dough to become a well-risen loaf of bread. (It's also instrumental for making wine and beer.)
Instant yeast came along about 30 years ago and has become more popular as its availability has increased. Because none of the yeast cells die during packaging, it requires 25% less instant yeast than active dry yeast to leaven a loaf. The biggest advantage of instant yeast is that it dissolves directly in dough without having to be hydrated in warm water the way active dry yeast often does.
To substitute instant yeast for active dry, use 25% less instant. When substituting instant yeast for fresh yeast, use one-third the amount called for; that is, for every ounce of fresh yeast, use 1/3 ounce of instant.
Double-check the expiration date on the package before buying and using.
Use straight from the package; no need to hydrate it first.
Unopened, instant yeast stays good for at least a year.