Temperature × recipe

Spelt Hearth Loaf at 3640°F

Adjusted timing: 8.7h bulk + 17.4h proof (multiplier 2.90×).

Baseline bulk (76°F)
3h
Adjusted bulk
8.7h
Baseline proof
6h
Adjusted proof
17.4h
Multiplier
2.90×
Activity
dormant
Target hydration
70%
Bake temp
450°F

Why the timing shifts

Refrigerator territory — used for overnight retard during proofing or bulk slowdown. 12-16 hours at this temperature is equivalent to 1-1.5 hours at 76°F baseline. Essential for flavor development in artisan sourdough. Cold retard improves shape retention, enables flexible scheduling, and develops deeper tangy flavors. Place dough in floured banneton, cover, refrigerate at this temperature.

Technique for Spelt Hearth Loaf

Short autolyse (20 min). 2-3 GENTLE stretch-and-folds (spelt gluten tears easily). 3h bulk. Shape carefully, floured banneton, 6h cold retard. Bake in dutch oven 450°F: 20 min lid on, 18 min off.

Calculator pre-set to these values

Multiplier at 38°F
2.9×
Adjusted bulk ferment
8.7 h
Adjusted final proof
17.4 h
How the math works

Multipliers are piecewise-linear interpolations between reference points measured by Myhrvold et al. in Modernist Bread vol 3. 76°F is the baseline (1.0×); every 10°F drop roughly doubles fermentation time, and every 10°F rise roughly halves it.

Sources: Myhrvold, Modernist Bread vol 3 (temperature multipliers); Peter Reinhart — Whole Grain Breads, Spelt chapter.