Cold fermentation
Dough chilled at about 4°C (39°F) for 12 to 72 hours ferments slowly. Cold slows the yeast a lot, but bacteria and enzymes keep working. Bacteria build acids, and enzymes turn starch and protein into sugars and flavor compounds.
Deeper crust color
Enzymes turn starch into sugars, and those sugars brown at the crust, so cold-fermented loaves bake darker. Cold dough is also firmer, which makes it easier to shape and score cleanly.
Test yourself
Questions from the interactive lesson, with the answer and the why.
Why does cold fermentation build more flavor?
Slow yeast gives acids and enzymes time to work. More time lets bacteria and enzymes make acids, sugars and flavor compounds.
True or false: In the fridge the yeast slows, but enzymes in the flour keep breaking starch into sugars.
True. Enzymes in flour keep working slowly in the fridge, turning starch into sugars.
Fill the blank: Cold slows the yeast, but bacteria and ___ keep producing flavor.
Cold slows the yeast, but bacteria and enzymes keep producing flavor. Enzymes keep freeing sugars and flavor compounds from flour.
What went wrong? You check your dough after eight hours in the fridge, see it has barely grown, and toss it.
Cold slows yeast, so little growth is normal. The dough is fermenting slowly and building flavor.
You want a deeper brown crust without raising the oven temperature. What do you try?
Chill the dough for a day or two first. A long cold ferment builds sugars that brown at the crust.