Yeast

Yeast is a biological leavening agent made up of living microorganisms from the Saccharomyces cerevisiae species. When combined with warm water and sugar, the yeast cells produce carbon dioxide, which causes the dough to rise. It is used in the baking of bread, rolls, cakes, sweet braided loaves, and other leavened baked goods. It is available fresh in block form or dried as granules or powder. Fresh yeast has a shorter shelf life and a stronger yeasty flavour, while dried yeast is more shelf-stable and convenient. Activation temperature is critical, water above 50 °C will kill the yeast cells and prevent the dough from rising.