Why I switched to a 36-hour cold retard
For about a year my schedule was simple: mix in the morning, shape in the evening, bake straight out of the fridge the next morning. Roughly 12–14 hours of cold proof. It worked fine. Then a busy week forced me to leave the dough in for a day and a half, and the loaf that came out was the best I'd made in months.
What changed
The flavour got noticeably more sour, but not in the sharp, vinegary way I was afraid of. The crust blistered more and browned faster, which I put down to extra sugars from the longer breakdown of starch. The ear also opened better — the cold, stiff dough held the score cleanly.
The numbers
| 12 h retard | 36 h retard | |
|---|---|---|
| Bulk at 24 °C | 4 h 30 min | 3 h 45 min |
| Fridge temperature | 4 °C | 3 °C |
| Bake | 20 + 22 min | 20 + 20 min |
| Sourness (my scale, 1–5) | 2 | 4 |
The key adjustment was cutting bulk fermentation short. If you take the dough as far as you normally would and then leave it for 36 hours, it overproofs and flattens out. Ending bulk at around 50% rise instead of 75% fixed that.
Under-proof the bulk, let the fridge finish the job.
What didn't change
Crumb structure was basically the same. If anything, slightly tighter. If you are chasing a very open crumb, a longer retard won't get you there on its own.