On Food and Cooking

in the 1920s, has been removed from the
fermentation tank and dried into granules
with a protective coating of yeast debris.
The yeast cells are dormant and can be
stored at room temperature for months.
The cook reactivates them by soaking
them in warm water, 105–110ºF/ 41–
43ºC, before mixing the dough. At cooler
soaking temperatures, the yeast cells
recover poorly and release substances
that interfere with gluten formation
(glutathione).
Instant dry yeast, an innovation of the
1970s, is dried more quickly than active
dry yeast, and in the form of small
porous rods that take up water more
rapidly than granules. Instant yeast
doesn’t need to be prehydrated before
mixing with other dough ingredients, and
produces carbon dioxide more vigorously
than active dry yeast.