When baking bread at home, most people use packaged yeast to make the dough rise. Active dry yeast and fast-acting yeast are the two most common forms of yeast for home use. Either can be used in a bread recipe if a few modifications are made.
There are many names for fast-acting yeast, but they are all the same type of yeast and work in the same way. Fast-acting yeast is sold as instant yeast, bread machine yeast and Fleischmann's RapidRise yeast.
One packet of active dry yeast contains 1/4 oz. of yeast, which is about 2 tsp. When using fast-acting yeast, you should use 25 percent less, which will be 1 1/2 tsp. in most recipes.
Although active dry yeast should be mixed with water before incorporating it into the dough, using this method with fast-acting yeast will negate its benefits. Instead, mix fast-acting yeast with the dry ingredients and add the liquid ingredients that have been heated to about 120 degrees F.
When using fast-acting yeast, the dough should double in size within about 10 minutes after you stop kneading it. At this point, punch it down, shape it into a loaf and let it rise again until doubled in size, about an hour.
Fast-acting yeast can be used for longer rise times, if you prefer. Just use it exactly as you would use active dry yeast, but add a little sugar to the water before mixing in the fast-acting yeast.