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 An Unusual Chemical Leavening: Hartshorn The leavening that doesn’t involve an acidbase reaction is ammonium salts — ammonium carbonate and/or carbamate — which were once known as “hartshorn” because they were produced by the distillation of deer antlers (Hartshorn was also a common source of gelatin.) When these compounds are heated to 140ºF/60ºC, they decompose into two leavening gases, carbon dioxide and ammonia, and don’t produce water They’re especially suited to thin, very dry cookies and crackers with a large surface area to release the pungent ammonia during baking Baking Powders and Other Chemical Leaveners Yeast cells produce carbon dioxide slowly, over the course of an hour or more, so the ... distillation of deer antlers (Hartshorn was also a common source of gelatin.) When these compounds are heated to 140ºF/60ºC, they decompose into two leavening gases, carbon dioxide and ammonia, and don’t... Hartshorn The leavening that doesn’t involve an acidbase reaction is ammonium salts — ammonium carbonate and/ or carbamate — which were once known as “hartshorn” because they were produced by the distillation of deer antlers... don’t produce water They’re especially suited to thin, very dry cookies and crackers with a large surface area to release the pungent ammonia during baking Baking Powders and Other Chemical Leaveners