Convert 7g (1 Packet / 2¼ tsp) Fresh Cake Yeast to Sourdough Starter (1000g Flour Recipe)
Zero-drift flour and liquid deduction math for converting 7g of fresh cake yeast into 50%–125% hydration sourdough levain on a 1000g base.
Here is the conversion in one line for a 1000g flour and 700g liquid dough built with 7g (1 Packet / 2¼ tsp) fresh cake yeast: 33.3g of ripe 100% hydration starter, deducted from the main mix as 16.7g flour and 16.7g water, giving 983.3g and 683.3g. Standard 20% baker's math on the same 1000g base wants 200g of starter and 900g / 600g.
- Direct Yeast Equivalent
- 33.3g StarterDeduct 16.7g flour & 16.7g water
- 20% Artisan Inoculation
- 200g StarterDeduct 100g flour & 100g water
- Adjusted Main Flour/Water
- 900g / 600gPreserves 1000g 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
Two Ways to Convert 7g Fresh Cake Yeast: Packet Equivalency vs 20% Inoculation
Starter hydration shifts the deduction asymmetrically: a stiffer levain carries more flour and less water per gram.
| Levain Hydration | Direct Yeast Match (Deductions) | Adjusted Dough (Direct Match) | Standard 20% Levain (Deductions) | Adjusted Dough (Standard Match) |
|---|---|---|---|---|
| [Your Formula]: 1000g / 75% | hidden 19g F + 14.3g W | → 981g / 685.7g | hidden 114.3g F + 85.7g W | → 885.7g / 614.3g |
| Leaner Dough: 400g / 100% | hidden 16.7g F + 16.7g W | → 383.3g / 263.3g | hidden 40g F + 40g W | → 360g / 240g |
| Wetter Dough: 500g / 125% | hidden 14.8g F + 18.5g W | → 485.2g / 331.5g | hidden 44.4g F + 55.6g W | → 455.6g / 294.4g |
| Tighter Dough: 1000g / 50% | hidden 22.2g F + 11.1g W | → 977.8g / 688.9g | hidden 133.3g F + 66.7g W | → 866.7g / 633.3g |
| Looser Dough: 1000g / 100% | hidden 16.7g F + 16.7g W | → 983.3g / 683.3g | hidden 100g F + 100g W | → 900g / 600g |
Dynamic Stoichiometric Workbench (33.3g Starter)
Test custom loaf weights or alternative fermentation schedules directly against the 200g Starter benchmark above.
Why 7g Fresh Cake Yeast Cannot Be Swapped in 1000g Flour Without Deducting Starter Water
Water is the silent variable in this swap. 7g of fresh cake yeast brings essentially no water with it, but 33.3g of levain brings 16.7g. Add that to 700g without deducting it and the 1000g dough lands well above 70% hydration and spreads.
Direct packet scaling of 7g (1 Packet / 2¼ tsp) Fresh Cake Yeast maps to 33.3g starter (-16.7g flour / -16.7g water), while artisan baker's math standardises inoculation at 20% of 1000g (200g starter, leaving 900g main flour and 600g liquid).
3-Step Conversion Checklist (7g Fresh Cake Yeast → Sourdough in 1000g Flour)
- Autolyse First: Combine 900g flour with 600g water (holding back 10% for salt) and rest 45 minutes.
- Add 200g of Ripe Levain: Pinch in the culture, add 2% salt with the reserved water, and mix until the dough is cohesive.
- Four Folds: Space two stretch and folds and two coil folds 30 minutes apart to build gluten without tearing the gas cells.
- Bulk, Shape and Retard: Reach the target rise, shape, and refrigerate 12–16 hours at 38°F before the final bake.
Key Baker's Math Questions (Direct Yeast Equivalent: 33.3g Starter)
How much flour and water do I subtract when adding 200g starter to 1000g flour?
At 100% starter hydration, subtract 100g flour and 100g water/milk from your 1000g flour recipe (leaving 900g flour and 600g liquid).
How do I convert a sweet or enriched recipe with 7g of Fresh Cake Yeast?
The grain and water deduction is identical, but reduce the sugar by about 10%–15%, because the 4.0 – 5.5 hours at 76°F (24°C) sourdough ferment converts more of it than a two-hour commercial rise.
Can I convert a 1000g dough that already contains a preferment or poolish?
Yes, but dissolve the preferment's commercial yeast into the main mix first so the full 7g of leavening power is counted. Then deduct 16.7g flour and 16.7g water for the levain you are adding.