In his Classic Focaccia recipe, author Peter Reinhart sings the praises of the long, slow rise. But at the same time, he uses instant yeast (also called quick-rise, rapid-rise, or fast-rising yeast) to leaven the dough. At first, that might seem contradictory, yet it isn’t. “Quick-rise yeast is really misnamed,” Reinhart explains. “Cell for cell, the yeast is no more potent than active dry yeast or fresh compressed yeast.” But because of the way it’s processed, instant yeast grains are small enough to be mixed directly (“instantly”) into dry ingredients without first being dissolved in water and proofed, a requirement with active dry yeast.
More important, instant yeast is highly concentrated, so you can use 25 percent less of it:
3/4 teaspoon instant yeast = 1 teaspoon active dry
So with instant yeast, you can abide by the artisan baker’s maxim and “use just enough yeast to get the job done and no more.” Using less yeast can prolong the rising time, but “this allows time for natural sugars in the flour to break out of the starch molecules and produce more flavor,” Reinhart says—precisely why bakers love the long, slow rise.