To convert regular yeasted bread recipe to sourdough recipe, we need to do three things:
- Calculate the equivalent weight of sourdough starter.
- Calculate how much flour to add on top of the sourdough starter.
- Calculate how much water to add on top of the sourdough starter.
Sourdough starter is the leavening agent which will replace the commercial yeast in the recipe. Since the sourdough starter contains flour and water on its own, we need to recalculate the weight of flour and water to be added into the dough. The remaining weights of any other ingredients in the regular yeasted bread can be kept the same for the sourdough bread.
Is sourdough starter the same as yeast?
Sourdough starter contains many wild yeast and bacteria while bread leavened with commercial yeast only contains yeast, with a very small population of bacteria. The lactic acid bacteria in sourdough starter releases lactic and acetic acids into the dough which brings about some important benefits over breads leavened with commercial yeast.
- Imparts a complex sour flavor to the bread; lactic acid gives us a mild yogurt-like sourness while acetic acid imparts a sharp sour bite akin to vinegar.
- Tightens the gluten in the dough which increases dough strength in weak doughs, allowing the dough to better hold its shape.
- Counteracts the effects of phytic acid, allowing our bodies to better absorb nutrients from the bread; phytic acid inhibits our bodies from absorbing iron, zinc and calcium.
How do I substitute instant,dry and fresh yeast for sourdough starter in breads?
Commercially sold yeast is made available in a highly concentrated form; the yeast population in sourdough starter exists in a much more diluted form. Hence, to achieve the same leavening ability as commercial yeast, we need to inoculate the dough with a much higher quantity by weight of sourdough starter.
|Type of Yeast||Weight of Yeast||Equivalent Weight of Sourdough Starter (100% hydration)|
|Instant & Dry Yeast||10 grams||300 grams|
|Instant & Dry Yeast||20 grams||600 grams|
|Instant & Dry Yeast||30 grams||900 grams|
|Fresh Yeast||10 grams||140 grams|
|Fresh Yeast||20 grams||280 grams|
|Fresh Yeast||30 grams||420 grams|
If the bread recipe calls for 10grams of fresh yeast, you will need 140 grams of 100% hydration sourdough starter to achieve the same leavening ability.
The yeast to sourdough starter conversion table above assumes that your sourdough starter doubles in volume every 4 hours at 25 Celcius after a 1:1:1 feeding. If your sourdough starter takes a longer time to double in size after feeding, you will need to use a higher quantity of sourdough starter from what is stated above.
Fresh yeast is not as strong as instant and dry yeast, hence we need a lesser amount of sourdough starter to get the same leavening ability.
The table gives us a 15 times increase in weight of flour in the sourdough starter for instant and dried yeast, and a 7 times increase in weight of flour in the sourdough starter for fresh yeast.
If the recipe calls for example 10 grams of instant yeast, the weight of flour in our sourdough starter would be 10 grams multiplied by 15 which is 150grams. Since we are using 100% hydration sourdough starter, the total sourdough starter weight would be 150grams (flour) + 150grams (water) = 300grams.
How long should bulk fermentation and final proofing be for the newly converted sourdough bread recipe?
Bulk fermentation is considered complete after the dough has risen by about 30-50%. The time it takes for the dough to reach the desired rise during bulk fermentation will be the same as the final proofing time. If the dough takes 3 hours to rise by 40% during bulk fermentation, final proofing time should be about 3 hours as well.
We should observe and listen to our dough, and it will let us know if fermentation has taken place sufficiently.
An accurate way to gauge the progress of fermentation in the dough is to look at the volumetric rise of the dough, since carbon dioxide gasses from the fermentation reaction causes the dough to rise.
Strictly following the timings in the recipe will lead to inconsistent and inferior breads.
The rate of fermentation is dependent on the strength of your sourdough starter, and the dough’s temperature during fermentation; these two variables varies throughout the year, and hence fermentation time will change as well.
A weaker sourdough starter, and a lower fermentation temperature increases fermentation time. Different dough have different optimal fermentation times throughout the year, and following a strict fermentation timing will lead to underproofing and overproofing of your dough.
If you want to increase the sourness of your sourdough bread, submit the dough through a cold retardation process, which means letting the dough go through final proofing in the refrigerator overnight for 10-12 hours. Do not go past 12 hours, as the dough will start to unravel and have difficulty holding its shape.
How to calculate flour and water requirements for the newly converted sourdough bread recipe?
|Ingredients||Regular Yeasted Bread||Equivalent Sourdough Bread|
|Flour||1000 grams||850 grams|
|Water||700 grams||550 grams|
|Dry Yeast/Sourdough Starter||10 grams||300 grams|
|Salt||20 grams||20 grams|
|Honey||50 grams||50 grams|
Since sourdough starter contains flour and water, we need to recalculate the amount of flour and water to add into the mix to arrive at the same weights of flour and water as the regular yeasted bread. Every other ingredient aside from flour and water will remain the same weight for the sourdough bread as per the regular yeasted bread.
In the table above, we can see that we need 300 grams of 100% hydration sourdough starter to achieve the same leavening ability as 10 grams of dry yeast. The 300 grams of 100% hydration sourdough starter consists of 150 grams of flour and 150 grams of water.
To get the new weights of flour and water in our sourdough bread:
New flour weight = Flour weight in regular bread – Flour weight in sourdough starter
New flour weight = 1000 grams – 150 grams
New flour weight = 850 grams
New water weight = Water weight in regular bread – Water weight in sourdough starter
New water weight = 700 grams – 150 grams
New water weight = 550 grams
Pancakes, waffles and crepes does not need conversion!
Since pancakes, waffles and crepes have about the same consistency as sourdough starter, we can directly replace the flour and water requirements of these recipes with the flour and water in the sourdough starter. Just add or reduce water/milk to achieve the desired batter consistency.