Yeast

Yeast is a single-celled fungus used as a biological leavening agent in bakery and food production. Baker’s yeast (Saccharomyces cerevisiae) ferments sugars in dough, producing carbon dioxide gas and ethanol. The carbon dioxide becomes trapped in the gluten network, causing the dough to rise and giving baked products their characteristic open, airy crumb structure.
Yeast is available in several forms: compressed (fresh) yeast, active dry yeast, and instant (fast-acting) dry yeast. Each form differs in moisture content, shelf life, and activation requirements. In industrial bakeries, compressed yeast is preferred for its high fermentation activity, while home bakers often use dry yeast for convenience. Beyond leavening, yeast contributes to flavor development through fermentation byproducts and plays a role in dough maturation and gluten conditioning.
Discover more about yeast — including types, dosage guidelines, and fermentation techniques — in the articles below.