leavens

Leavens is a term commonly associated with leavening, the set of substances and processes used to make dough or batter rise. In baking, leavening can be biological, chemical, or mechanical, and the resulting gas production creates a light, porous crumb.

Biological leavening relies on living microorganisms, primarily yeast (Saccharomyces cerevisiae) and, in some cases, lactic acid bacteria found in sourdough starters. Yeast ferments sugars, producing carbon dioxide and alcohol. The gas forms bubbles within a gluten network, causing the dough to expand. Sourdough, containing a mixed culture of wild yeast and bacteria, adds distinctive flavor and acidity to bread.

Chemical leavening uses reactants that release carbon dioxide through acid-base reactions. Baking powders, which combine an acid with a carbonate, release gas when moistened and again when heated. Baking soda requires an acid to react, such as yogurt, buttermilk, or cream of tartar. Ammonium carbonate, used in some traditional cookies, decomposes to produce gas and a crisp texture. Chemical leavening is valued for predictability and speed, especially in cakes, cookies, and quick breads.

Mechanical leavening involves physically incorporating air or steam into the batter or dough, as by whisking, creaming butter and sugar, or folding in beaten egg whites. Steam, generated from high-moisture batters during baking, also contributes to leavening in products like pastries and popovers.

Leavens can be used alone or in combination, depending on the desired texture, flavor, and speed of production. The term leavens the broader concept of agents and techniques that raise dough and batter in baking.