November 4, 2010 - 10:17am
Hydration Level
Please help me with my brain freeze. I thought I was pretty good at math but hydratin levels always confuse me. If I use 8oz. of 100% starter with 16oz. water and 24oz. flour, what is the hydration %. ?
Thanks
Paul
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The 100% starter has 4oz water and 4oz flour. Add the 16oz water to total 20oz, and 24oz flour makes 28oz. 20/28=.71428... or 71% hydration.
cheers,
gary
Following a previous thread on the same topic, the net hydration is about 72%. The formula for this calcuation may be sufficiently inconvenient it's worth capturing it in either a spreadsheet or a "smart" calculator for future use.
What you're trying to calculate is basically this:
overall_hydration = (proportion_of_starter x starter_hydration) + (proportion_of_final x final_hydration)
In your case (assuming those "16 oz water" is a weight because if they're "fluid ounces" then the answer is "I dunno"), your
Calculating out all those fractions gives an overall hydration of 13/18 = 0.722... ~= 0.72 = 72%.
(An alternate method of calculation is to tot up all the flour [both in the starter and in the final] and all the water [the starter and the final and other ingredients].)
Gary's method (which is the alternate method I mentioned of totting up all the flour and all the water) is exact.
The method I gave (mentioned on the earlier thread) is supposed to be easier to deal with, at the cost of being not quite exact. It was intended to be easier to both understand and calculate ...but in hindsight I'm not sure that's true.
Anyway, if you're going to capture the calculation in a spreadsheet or a smart calculator, it makes more sense to use Gary's exact method.
Still confused. Both of these results are different (although only slightly).
Hello,
Gary's answer is correct and I understand it - maybe if I restate it in a little more detail it will help?
First, hydration = water / flour
Now, you gave two components forming the final dough's hydration:
- 8oz. of 100% starter = 4 oz water and 4 oz flour (hydration = 4/4 = 1 or 100%)
- 16 oz water and 24oz. flour (hydration = 16/24 = .66 or 66%)
- You wanted the
combined or final
hydration 20 oz water and 28 ox flour (hydration = 20/28 = 5/7
= 0.7142857142857143
so the combined hydration is 71.43 %
Hope this helps.
Ben
I got it. Now for every ounce of water I add to this mixture I increase the hydration roughly 3%
Thanks
Paul
Paul,
You are correct that "that every additional ounce will increase the total hydration by a FIXED amount" - the FIXED amount is
1/28 = 0.0357142857142857 OR in Baker's % = 3.57 %
bEN