Bulk fermentation

Bulk fermentation is the period after the dough is fully mixed, when it sits together as one mass and rises for the first time. This is when the wild yeast produces most of the gas that will become the loaf's structure, and the bacteria in the starter build the acidity that gives sourdough its characteristic tang.

Judging bulk fermentation by time alone is unreliable because room temperature, starter strength and hydration all change how quickly dough ferments. Most experienced bakers watch for visual cues instead: the dough should look noticeably puffier, feel jiggly when the container is nudged, and may show some bubbles at the surface, often having grown by 30 to 75 percent in volume depending on the recipe and temperature.

A straight-sided container with volume markings makes it much easier to judge rise consistently from bake to bake. A common mistake is ending bulk fermentation purely by the clock from a recipe written for a different kitchen, which can leave dough under-proofed in a cold house or over-proofed in a warm one. Pulling dough too early leaves weak structure and a dense crumb, while going too far can make it slack and hard to shape.