yeast or 1 tsp baking powder

Yeast refers to unicellular fungi of the Saccharomyces genus, most commonly Saccharomyces cerevisiae, which are used as leavening agents in baking and fermentation. These microorganisms reproduce through budding and possess the metabolic capacity to convert sugars into carbon dioxide and ethanol, making them essential for bread rising and alcoholic fermentation. Commercial yeast is available in several forms: active dry yeast consists of dormant yeast cells; instant (or bread machine) yeast has smaller particles and faster hydration; and fresh compressed yeast contains higher moisture content. Each variety performs similarly but differs in particle size, moisture content, and rehydration speed.\n\nBaking powder is a chemical leavening agent composed of sodium bicarbonate (baking soda) combined with acid salts (typically cream of tartar or sodium aluminum sulfate) and an inert filler like cornstarch. Unlike yeast, which requires fermentation time and living organisms, baking powder produces carbon dioxide gas immediately upon activation through moisture and heat, creating rapid leavening without fermentation.

Yeast is essential in bread baking, producing the characteristic flavor, texture, and rise through fermentation, which can require 1–24 hours depending on the type of bread and desired flavor development. Beyond bread, yeast is crucial in brewing, winemaking, and the production of foods like tempeh and nutritional yeast. Baking powder, by contrast, is used in quick breads (muffins, biscuits, cakes), pancakes, and pastries where immediate leavening is desired and fermentation flavor is not required. The choice between yeast and baking powder fundamentally alters texture: yeast produces an open crumb structure with complex flavor, while baking powder yields a more uniform, tender crumb with neutral taste.