The organic chemical activity whereby yeast changes sugar to carbon dioxide. Fermentation, also known as the first rise or primary or bulk fermentation, is the stage when the dough is still dealt with in one piece before being divided and shaped. It is also during this first stage that most of the desired flavor will develop and, of course, that the dough’s appearance will change dramatically as it rises. Low temperature creates a long, slow fermentation and a complex bread, while a high temperature will cause quick fermentation and, frequently, an unpleasant odor and flavor. It is, in fact, the baker’s ability to elicit proper fermentation that translates to exemplary breads.