Converting High-Yeast 10g (1½ Packets) Fresh Cake Yeast to Sourdough Levain in 400g Flour
High-inoculation conversion math comparing 47.6g direct yeast equivalency vs. 80g (20% baker's math) for 400g flour recipes.
There are two defensible answers to this conversion, and the difference matters. Packet-equivalency treats 10 grams of Fresh Cake Yeast as a fixed quantity of leavening power, so you need 47.6g of ripe starter and must remove 23.8g flour plus 23.8g water from the 400g base. Baker's math instead standardises on 20% inoculation, giving 80g of starter on the same 400g flour with 360g flour and 240g liquid left in the bowl.
- Direct Yeast Equivalent
- 47.6g StarterDeduct 23.8g flour & 23.8g water
- 20% Artisan Inoculation
- 80g StarterDeduct 40g flour & 40g water
- Adjusted Main Flour/Water
- 360g / 240gPreserves 400g total system flour at 20% levain
- Sourdough Bulk Window
- 4.0 – 5.5 hoursAt 76°F (24°C) vs. 1–1.5 hrs for commercial yeast
Yeast-to-Sourdough Conversion Table: 10g Fresh Cake Yeast on a 400g Base
Use the 100% hydration row as your working formula unless your levain is deliberately stiff or liquid.
| Starter Hydration | Packet-Equivalent Starter (Deductions) | Adjusted Main Dough (Packet Mode) | 20% Artisan Starter (Deductions) | Adjusted Main Dough (20% Mode) |
|---|---|---|---|---|
| [Baseline]: 500g / 100% | hidden 23.8g F + 23.8g W | → 476.2g / 326.2g | hidden 50g F + 50g W | → 450g / 300g |
| Stiffer Starter: 1000g / 125% | hidden 21.2g F + 26.5g W | → 978.8g / 673.5g | hidden 88.9g F + 111.1g W | → 911.1g / 588.9g |
| Wetter Starter: 400g / 50% | hidden 31.7g F + 15.9g W | → 368.3g / 264.1g | hidden 53.3g F + 26.7g W | → 346.7g / 253.3g |
| Lighter Starter: 400g / 100% | hidden 23.8g F + 23.8g W | → 376.2g / 256.2g | hidden 40g F + 40g W | → 360g / 240g |
| Heavier Starter: 400g / 75% | hidden 27.2g F + 20.4g W | → 372.8g / 259.6g | hidden 45.7g F + 34.3g W | → 354.3g / 245.7g |
Real-Time Dough & Starter Scaling Sandbox
Scale this Replacing 10g (1½ Packets) Fresh Cak specification up or down on your digital scale with zero hydration drift.
Balancing Osmotic Stress & Hydration When Replacing 10g Fresh Cake Yeast in 400g Flour
Hydration drift is the most common way this conversion goes wrong. Adding 47.6g of levain to 400g flour and 280g water without the 23.8g deduction pushes the dough to 71.7% true hydration, and the extra free water is exactly what turns a slack dough into a puddle.
The dough weight of the converted batch is lower than the original. Removing 10g of fresh cake yeast and adding 47.6g of sourdough culture changes the total mass of a 400g flour dough, which is why the finished loaf bakes slightly differently even though the flour and water balance is identical.
3-Step Conversion Checklist (10g Fresh Cake Yeast → Sourdough in 400g Flour)
- Prepare the Levain Ahead: Build 80g of ripe 100% hydration starter and feed it early enough that it domes before you mix the 400g dough.
- Mix Flour and Liquid (360g + 240g): Combine the adjusted flour and liquid, reserving 10% of the water for the salt.
- Add Starter and Salt: Work in 80g of levain plus 2% salt, then perform 4 sets of stretch and coil folds at 30-minute intervals.
- Bulk to +50% and Shape: Let the 400g batch rise to the target aliquot volume, preshape, bench rest 20 minutes, and shape before a long cold retard.
Diagnostic Answers: Replacing 10g (1½ Packets) Fresh Cake Yeast
Can I convert a 400g dough that already contains a preferment or poolish?
Yes, but dissolve the preferment's yeast into the main mix first so the full 10g of leavening power is counted. Then deduct 23.8g flour and 23.8g water for the levain you are adding.
Can I halve the recipe and still use 10 grams of Fresh Cake Yeast?
You can, but the effective inoculation doubles, so 47.6g of levain on half the flour ferments faster than the original. Plan for a shorter bulk.
How much longer does sourdough take to rise than 10g of Fresh Cake Yeast?
Expect bulk fermentation on a 400g flour batch to take 4.0 – 5.5 hours at 76°F (24°C), roughly 3 to 4 times longer than commercial fresh cake yeast.