February 23, 2011 - 1:15pm

## KA starter to Peter Reinhart?

Hi everyone,

I recently bought a sourdough starter from King Arthur and got it going. I was wondering how to convert it to be suitable for the recipes in Artisan Breads Everyday. The feedings consist of a 1/2 C water and 1 C flour. If you want to see the more detailed instructions, here's a link: http://www.kingarthurflour.com/tips/sourdough-tips.html#a3

There's nothing in this book about the hydration of the starter so I'm at a loss how to figure it out.

Thanks everyone!

Your bread won't know where your starter came from, it will respond only to the chemistry of the starter formula. But you do have to perform a few calculations to know what the final hydration level is for your bread dough.

Let's say you have 100 grams of 83% hydrated starter, consisting 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.

Last point, and perhaps the most essential. Forget everything you ever knew about bulk measurements and get yourself a scale. Determine the relative of the flour you're using (e.g. 1/2 cup = 2.25 ounces/64 grams) and focus on weighting ingredients. You'll be much more consistent, and a lot happier, in the end.

Artisan breads everyday has all the baker's formulas in the back of the book.(Why are they not with the recipes? Argh!)

Reinhart uses a 75% hydration formula for this book and the recipes in the Whole Grain book, so you will want to work the starter toward this %.

I have to agree with flournwater that a scale will make this easier and more accurate and you'll never again have to scrape honey out of a measuring cup.

KA uses a 1 cup=4.25 oz standard for its AP flour, so 1 cup of flour is about 120 g. A half cup of water is 118 g, so the starter works out to be about 98% hydration.

Chances are, your cup of flour weighs more, so your starter will be less hydrated.

Thanks for the responses! I do have a scale (I only bake bread by weight) so I'll start using that. I need to do some research on percentages since I'm completely in the dark about how to convert my starter to 75% hydration.

=== I need to do some research on percentages since I'm completely in the dark about how to convert my starter to 75% hydration. ===Well, you can do a lot of detailed arithmetic and feeding odd amounts (e.g. 43.217 grams of ...).

Or... you can take 25g of starter of any hydration and feed it with the desired hydration. In this case that would be 116g flour + 84g water, which gives you a nice round amount of 200g starter. Let that ripen, discard 125g, and feed with 58g flour + 42g water. From then on feed by using/discarding 100g of the starter and feeding with 58g flour + 42g water.

You can just ignore that effect of that initial 25g on the eventual hydration: after 3 or 4 feedings the difference will be much smaller than your ability to scrape exactly 100g out for a feeding.

sPh

Suppose you had an old recipe that had it's own starter and you wanted to use your own instead. How do I figure out what the recipe starter hydration is. It uses yeast, etc.

My starter is Peter Reinharts and is about 7 months old and works wonderfully. (100% hydration) I have an old recipe I used to use from time to time and now want to use my own starter. I made it not too long ago using my present starter and it came out great. Then subsequent bakings, not so good. I attributed the change to not correctly adjusting the recipe for the lack of or too much of the liquid in the starter. But when I look at what the recipe originally calls for, it is more than I can figure out.

Any help would be greatly apprciated. Jean P. (VA)

Start a new thread on the forum with your question and provide the "recipe" for the old starter. You'll get a better response to your inquiry if it isn't tagged onto someone elses thread.

Is there any way I can do that without typing it all over again? Thanks, JP

Yes. Just cut your text and save it. You can use your saved text by pasting it into your repost.