The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

Bread Dough Formula Math Dilemma (Some Help, I Hope)

flournwater's picture
flournwater

Bread Dough Formula Math Dilemma (Some Help, I Hope)

From time to time I read posts with questions like this:


"I want to use 435 grams of starter at 70% hydration in a bread dough formula that calls for 500 grams of flour at 60% hydration.  How do I figure out how much flour and water I need to add in order to meet that requirement?"


Here's a primer that should alleviate the headache you might normally experience trying to figure it out.


435 grams starter at 70% hydration means you'll divide 435 by 1.70 for a total of 256.  That means 256 grams of your starter is flour.  Now subtract the known flour weight from the total starter weight and you'll get 179 grams of water.   So your 70% hydrated starter is the product of 256 grams of flour and 179 grams of water.


The bread formula you're working with calls for 500 grams of flour with a 60% hydration level.  So all you have to do is make up the difference between the 256 grams of flour in your starter and the 500 total you need for the bread (500 minus 265 equals 244) and add that much new flour to the mix.  60% hydration for 500 grams of flour requires 300 grams of water.  You already have 179 grams of water in your starter, so all  you need to do is add another 121 grams of water and you've achieved your goal.


Total Starter Weight/Hydration Percentage (as a decimal) = weight of flour content


Total Starter Weight minus Flour content weight = weight of water in the starter


The principal applies, regardless of the hydration level of the starter.  Of course, for an 80% hydrated starter, you'd need to change the hydration percentage figure from 1.70 to 1.80 to identify the comparative weight ration of flour to water in your starter.


 


 

kolobezka's picture
kolobezka

but what about when the recipes just states "200g sourdough starter" without details about the hydratation.  How can one guess?

flournwater's picture
flournwater

It's not necessary (or a good idea) to guess.  If you have 200 grams of sourdough starter on hand you should know what the level of hydration is.  "Starter'" for sourdough breads often infers a sponge (barm), prepared using a seed culture and having a hydration level at or near 100%.

kolobezka's picture
kolobezka

if the recipe doesn´t give details about hydratation, i can simply suppose it is a 100% hydratation starter. ?

flournwater's picture
flournwater

Well, that's what I typically do.  Once you have a sense of how a sourdough formula for the variety of bread you're working on should feel in your hands you will inevitably make adjustments on your own.  Room temperture, humidity, variations between flour types, the health of your yeast, etc. will affect your dough regardless of how diligently you work to maintain consistency so understanding the "feel" of the dough will carry you over that final hurdle.  If you carefully note what you do each time you prepare the dough and compare the differences in ingredients and their temperatures, the atmosphere in the kitchen, etc. each time you work with a particular variety of bread you'll develop a certain intimacy with it and come to know with it's right with your eyes closed.


When I started baking bread I avoided formulas that were non-specific and gave only vague information e.g. 200 grams of starter, preferring to focus on those that offered more specific information like 200 grams of poolish/biga/ etc.  I know how to make a poolish and a biga so I can work with those descriptions -  IMO, "starter" is too generic a term (kinda like saying "pre-ferment" and not describing the type of pre-ferments they used) to handle when first exposed to serious (even for fun) bread making.