A Guide to Bulk Fermentation (How to Know When Your Dough Is Actually Ready)

Bulk fermentation is where most sourdough bakes go wrong. This guide explains exactly what to look for so you can stop guessing and start reading your dough properly

8/30/20263 min read

Bulk fermentation is the stage between mixing your dough and shaping it, and it is genuinely the trickiest part of sourdough to get right, especially when you are starting out. Overproof even slightly and you will lose a lot of the rise and structure you have worked for. Underproof and your loaf will be dense and gummy as it lacks the structure to hold the gas bubbles released as part of fermentation. The good news is that your dough gives you plenty of visual and physical clues, once you know what to look for.

What Is Actually Happening During Bulk Fermentation

From the moment your levain is mixed into your dough, the wild yeast and bacteria in your starter begin feeding on the sugars in the flour, producing carbon dioxide (which creates the bubbles and rise) and organic acids (which develop flavour). This continues until you shape the dough, which is where bulk fermentation officially ends.

The Signs Your Dough Has Finished Bulk Fermentation

You do not need to rely purely on the clock. Instead, look and feel for these signs:

• The jiggle test. Gently shake the bowl. A dough that has fermented enough will wobble and jiggle, because it is full of trapped gas.

• A domed, pebbled surface. Similar to a starter reaching peak, the surface should look slightly domed with a pebble-dashed texture from air bubbles just underneath the surface.

• Reduced stickiness. The dough surface should no longer feel as intensely sticky as it did at the start.

• Clean release from the bowl edges. If you gently nudge the dough away from the side of the bowl, it should come away cleanly rather than tearing or sticking stubbornly. The biggest test (although it is far to late to go back at this stage) is the 'dough dump', this is where you upend the bowl over your surface and see if the dough gently drops out of the bowl leaving it completely clean.

• Overall size increase. Most doughs will increase to somewhere between 1.5 and 2 times their original size by the end of bulk fermentation, though this varies by recipe and hydration.

How Temperature Affects This Stage

Warmer temperatures speed bulk fermentation up considerably, which is why using warm water when mixing your dough can help maintain a consistent dough temperature throughout, rather than the dough gradually warming up from a cold start. A dough kept in a proofing box or warm spot will finish bulk fermentation faster than one left in a cool kitchen.

When to Stop Folding

Coil folds are generally the gentlest technique to use during bulk fermentation, since they disturb the developing air bubbles the least. Most bakers stop folding altogether for the final 2 to 3 hours of bulk fermentation, once the dough is holding its own shape well, to avoid knocking out the structure that has built up.

What Overproofing Looks Like (And How to Rescue It)

An overproofed dough will feel very sticky again, almost as though it has gone backwards, and will likely spread out rather than holding a domed shape. If you catch this, do not panic. Overproofed dough can often still be salvaged, one popular trick is adding a splash of olive oil, herbs and salt grains, turning it into a rustic focaccia instead of a shaped loaf, since focaccia is far more forgiving of an overly relaxed dough.

A Final Tip

Using the same ingredients and the same temperature setup every time you bake removes a lot of the guesswork here. Bulk fermentation genuinely does become far more predictable once you have baked a handful of loaves under consistent conditions and learned roughly how long your specific setup takes.