January 20, 2010 - 3:25pm

## Check my Math?

I maintain my starter using 10g previous starter, 50g water and 60g bread flour. This technique has been working well for me, as suggested by MiniOven. She also pointed out in a previous thread that this is no longer a poolish -- since it is not 100% hydration...

My question (Mini or anyone)

Is my starter considered 83% hydration then? (5/6 is ~83.3%) or how do I figure the 1:5:6 ration into a percentage? I realize this is probably 7th grade math, but 7th grade was a LONG time ago. ;-)

What's the simplest way to build it back to 100% hydration for baking?

Thanks to any/all who reply.

Your starter is 83.3%, for exactly the reason you suggested. The 1 in the 1:5:6 ratio gets diluted fairly quickly. If you wanted to return to a 100% hydration, just start feeding equal amounts of flour and water, say 1:5:5 or 1:6:6 (or if you want to continue using 10g starter and end up with 120g of starter, 2:11:11).

I take the mature starter fed at 1:5:6 and mix it with 1:1 w:bf.

So if I have 100g of mature 83% hydration starter, I usually do 100g of w and 100g of bread flour. I guess that gives me a 83% starter and I need to adjust my build by giving it an additional 17% W?

Well, not quite. I didn't get down to splitting fractions, it isn't rocket science, so forgive me if I've assumed an acceptable error of less than 1% in any calculation here.

Your 100 grams of 83% hydrated starter consists of 55 grams of flour and 45 grams of water. 45 = 83% of 55. If you add 100 grams of water and 100 grams of flour your total will be 155 grams flour and 145 grams water or a hydration level of 93%. 145 = 93% of 155. So you'd need to add 100 grams of flour and 113 grams of water to develop a 100% hydrated starter. 55 grams flour + 100 grams flour = 155 grams. 45 grams water + 111 grams water = 155 grams water or 100% hydration.

I should have paid more attention in algebra. ;-)

I follow your math, but how dod you start with 55g of flour and 45g of water when my original refresh contained 50g of water and 60g of flour? Is it because you decreased each by 1/2 of the 10g carried over starter?

You want to take 100g of an 83% hydration starter (whose individual components consist of 45g water/55g flour) & end up w/ 300g a 100% starter (whose individual components consist of 150g water/150g flour)

150-45=105g water

150-55=95g flour

45+55+105+95=300g 100% starter

(the reason flournwater's numbers & mine aren't the same is that with his, you'll end up w/ a tad more than 300g. Preferrable to coming up short)

"Is it because you decreased each by 1/2 of the 10g carried over starter?"

No, it's because you needed only 100g of the resultant 120g after your refresh.

-d

This makes more sense to me than figuring it out the other way.

Thanks to everyone who replied.

Don't get discouraged, Chode. It's onlya bunch of numbers.

When you started your 83% hydrated starter with 50 grams of water and 60 grams of flour your final weight was 110 grams. In your current situation you're using 100 grams of flour. 50 grams of water is roughly 83% of the 60 grams of flour you originall used. But with the 100 grams of starter you're refreshing you're 10 grams short of your original formula total.

Here's a link that you might find useful. If I may suggest, print it out and play with it when you're working with formula adjustments. You can write on it and spill all kinds of things on it in the kitchen cuz it's always hanging here on line to print again if you need it.

But your link didn't come through...?

http://www.thefreshloaf.com/node/15217/bread-dough-formula-math-dilemma-some-help-i-hope