envelope active dry yeast

Active dry yeast is a commercial preparation of Saccharomyces cerevisiae, a single-celled fungus that has been dried and granulated for shelf-stable storage and convenient measurement. The yeast cells are dormant but viable; when rehydrated in warm liquid with food (typically sugar or flour), they resume metabolic activity and ferment carbohydrates into carbon dioxide and ethanol. Active dry yeast differs from instant yeast in that its granules are larger and contain more dead cells, requiring a brief rehydration period (called "blooming" or "proofing") before mixing into dough. A standard packet contains approximately 2.25 teaspoons or 7 grams of yeast.

Active dry yeast is the foundational leavening agent in bread baking, where it produces gas bubbles that create rise and texture in dough. It is employed in the preparation of breads, rolls, bagels, pizza dough, sweet doughs, and enriched doughs containing eggs and fat. Beyond bread, it is used in some beer and wine fermentation applications at the home level. Proper hydration and temperature management are critical; yeast is most active in the range of 75–80°F (24–27°C), becomes sluggish below 50°F, and dies above 120°F (49°C). Blooming yeast in warm water before incorporation confirms viability and ensures even distribution throughout the dough.