Converting High-Yeast 10g (1½ Packets) Fresh Cake Yeast to Sourdough Levain in 500g Flour
High-inoculation conversion math comparing 47.6g direct yeast equivalency vs. 100g (20% baker's math) for 500g 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 500g base. Baker's math instead standardises on 20% inoculation, giving 100g of starter on the same 500g flour with 450g flour and 300g liquid left in the bowl.
- Direct Yeast Equivalent
- 47.6g StarterDeduct 23.8g flour & 23.8g water
- 20% Artisan Inoculation
- 100g StarterDeduct 50g flour & 50g water
- Adjusted Main Flour/Water
- 450g / 300gPreserves 500g 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
Starter Deduction Grid for 10g (1½ Packets) Fresh Cake Yeast in 500g Flour
Exact starter weights and main dough flour/water deductions for 10g Fresh Cake Yeast in 500g flour so True Total Hydration never drifts.
| Starter Hydration Level | Levain Required by Yeast Weight | Flour & Liquid Left in the Bowl | Levain Required at 20% Inoculation | Corrected Main Mix |
|---|---|---|---|---|
| [Anchor]: 500g / 75% | hidden 27.2g F + 20.4g W | → 472.8g / 329.6g | hidden 57.1g F + 42.9g W | → 442.9g / 307.1g |
| One Step Down: 1000g / 100% | hidden 23.8g F + 23.8g W | → 976.2g / 676.2g | hidden 100g F + 100g W | → 900g / 600g |
| One Step Up: 400g / 125% | hidden 21.2g F + 26.5g W | → 378.8g / 253.5g | hidden 35.6g F + 44.4g W | → 364.4g / 235.6g |
| Two Steps Down: 500g / 50% | hidden 31.7g F + 15.9g W | → 468.3g / 334.1g | hidden 66.7g F + 33.3g W | → 433.3g / 316.7g |
| Two Steps Up: 500g / 100% | hidden 23.8g F + 23.8g W | → 476.2g / 326.2g | hidden 50g F + 50g W | → 450g / 300g |
Dynamic Stoichiometric Workbench (47.6g Starter)
Test custom loaf weights or alternative fermentation schedules directly against the 100g Starter benchmark above.
Balancing Osmotic Stress & Hydration When Replacing 10g Fresh Cake Yeast in 500g Flour
Flour mass moves too, and bakers tend to forget it. The 23.8g of pre-fermented flour inside 47.6g of levain means the true total flour of your dough is not 500g but 523.8g once the starter is added, which is what makes 70% the correct target rather than the naive 70%.
Proofing structure matters more once you cross over. A levain at 100% hydration is a paste rather than a liquid, so it disperses differently through the 500g of flour than the measured 350g of water it replaces, and the dough usually needs an extra set of folds in the first hour.
3-Step Conversion Checklist (10g Fresh Cake Yeast → Sourdough in 500g Flour)
- Prepare the Levain Ahead: Build 100g of ripe 100% hydration starter and feed it early enough that it domes before you mix the 500g dough.
- Mix Flour and Liquid (450g + 300g): Combine the adjusted flour and liquid, reserving 10% of the water for the salt.
- Add Starter and Salt: Work in 100g 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 500g batch rise to the target aliquot volume, preshape, bench rest 20 minutes, and shape before a long cold retard.
Key Baker's Math Questions (Direct Yeast Equivalent: 47.6g Starter)
Does the type of commercial yeast change the starter weight?
Yes. Fresh Cake Yeast has its own potency per gram, so 10g of it converts to 47.6g of sourdough culture rather than the 100g that the 20% rule would prescribe on a 500g base.
What salt level should I use on the converted 500g dough?
Keep 2% of the total system flour, which on a 500g base with 50g of starter flour is about 11g of salt.
Is a 500g sourdough conversion suitable for a pizza or focaccia base?
Yes, and long cold retarding is often an advantage for pizza. Mix 100g of levain into 450g flour and 300g water and refrigerate 24–48 hours.