Glossary

Active dry yeast

Active dry yeast is baker's yeast (Saccharomyces cerevisiae) dried into coarse granules that stay dormant until they meet water. Each granule has a protective outer layer of dried cells, which is why it is traditionally dissolved in lukewarm water before it joins the dough. It matters in baking because it keeps well on the shelf and lets you see foam before you commit your flour. A 7 g (0.25 oz) packet holds about 2¼ teaspoons, according to Red Star Yeast. See also: Instant yeast, Fresh yeast, Proofing and the guide "What Is Active Dry Yeast and How Does It Work?"