How to Replace 4g (1⅓ tsp) Fresh Cake Yeast with Sourdough Starter in a 400g Flour Recipe
Zero-drift flour and water deduction guide for converting low-yeast (4g fresh cake yeast) artisan or poolish doughs into 80g sourdough levain.
Here is the conversion in one line for a 400g flour and 280g liquid dough built with 4 g (1⅓ tsp) fresh cake yeast: 19g of ripe 100% hydration starter, deducted from the main mix as 9.5g flour and 9.5g water, giving 390.5g and 270.5g. Standard 20% baker's math on the same 400g base wants 80g of starter and 360g / 240g.
- Direct Yeast Equivalent
- 19g StarterDeduct 9.5g flour & 9.5g 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
Gram Weights for 400g Flour Sourdough Built from 4g Fresh Cake Yeast
Every figure is derived from the 400g flour / 280g liquid base formula and the 4g fresh cake yeast dose.
| Starter Water Ratio | Starter Weight & Hidden Flour/Water | Corrected Flour / Corrected Liquid | 20% Inoculation Weight | Corrected Flour / Corrected Liquid |
|---|---|---|---|---|
| 1000g flour @ 75% [Anchor] | 19g starter (10.9g F / 8.2g W) | 989.1g F / 691.8g W | 200g starter (114.3g F / 85.7g W) | 885.7g F / 614.3g W |
| 400g flour @ 100% One Step Down | 19g starter (9.5g F / 9.5g W) | 390.5g F / 270.5g W | 80g starter (40g F / 40g W) | 360g F / 240g W |
| 400g flour @ 125% One Step Up | 19g starter (8.5g F / 10.6g W) | 391.5g F / 269.4g W | 80g starter (35.6g F / 44.4g W) | 364.4g F / 235.6g W |
| 500g flour @ 50% Two Steps Down | 19g starter (12.7g F / 6.3g W) | 487.3g F / 343.7g W | 100g starter (66.7g F / 33.3g W) | 433.3g F / 316.7g W |
| 400g flour @ 100% Two Steps Up | 19g starter (9.5g F / 9.5g W) | 390.5g F / 270.5g W | 80g starter (40g F / 40g W) | 360g F / 240g W |
On-Bench Hydration & Fermentation Adjuster
Modify base flour mass, levain inoculation, or ambient kitchen temperature below to recalculate from this 19g Starter baseline.
Replacing Low-Inoculation 4g Fresh Cake Yeast in 400g Flour Without Shifting Hydration
Flour mass moves too, and bakers tend to forget it. The 9.5g of pre-fermented flour inside 19g of levain means the true total flour of your dough is not 400g but 409.5g once the starter is added, which is what makes 70% the correct target rather than the naive 70%.
If your original recipe used 4g of fresh cake yeast for a sweet or enriched dough, the 19g levain version usually needs its sugar reduced slightly, because the longer fermentation converts more of it and the finished crumb sweetens on its own.
3-Step Conversion Checklist (4g Fresh Cake Yeast → Sourdough in 400g Flour)
- Check the Starter Is Ripe: 80g of levain must be domed, bubbly and at full stretch; a flat starter slows the 4.0 – 5.5 hours at 76°F (24°C) window significantly.
- Combine 400g of Flour with the Adjusted Liquid: Pour 240g, saving 10% to dissolve the salt later.
- Fold in 80g Starter and 2% Salt: Add the levain, pinch through the dough, and work in the salt water.
- Ferment to +50%: Judge by volume in a straight-sided jar, then shape, retard overnight and bake on a preheated stone or in a Dutch oven.
Common Scaling & Troubleshooting Questions (19g Starter)
How do I convert a sweet or enriched recipe with 4 grams of Fresh Cake Yeast?
The flour 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.
Why does my converted 400g dough feel stickier than the original?
Almost always the 9.5g of hidden starter water was not deducted. Correct the liquid to 270.5g and the dough will tighten immediately.
Is a 400g sourdough conversion suitable for a pizza or focaccia base?
Yes, and long cold retarding is often an advantage for pizza. Mix 80g of levain into 360g flour and 240g water and refrigerate 24–48 hours.