In the 12 Steps of Bread Baking, this is step #3. During Bulk Fermentation, yeast feeds on available sugars and creates two bi-products of fermentation. These bi-products are carbon dioxide and alcohol. These bi-products make the dough rise to double in size and give rue dough flavor. Bulk Fermentation usually lasts 1 hour - 1 hour and 20 minutes at room temperature.