March 25, 2009 - 7:35pm

## Hydration % question

I'm new with sourdough and awful at math, it makes a wonderful combination for it. I have a question for converting a wet starter to a firm starter. If my starter is at 100% hydration, that means I am feeding it equal parts flour and water....got that. However, I am getting confused as to how to change it to firmer hydration %. For example, if I want to change it to 70%, do I just feed it 100% flour and 70% water? Do I need to adjust those amounts to take in account for the 100% my starter is? I've searched around on the forums and I'm still pretty confused. Sorry if this has been asked a million times before. I appreciate any help....and I hope that I've worded this without being too confusing.

hi i just wanted to tell you there's a site which explains all that very simply and clearly. its: wildyeastblog.com there's a baker's percentage tutorial thats excellent and part four is all about sourdoughs. hope this helps.

That site is great and thank you for pointing it out to me, but I still don't get it. Her example goes with the assumption that you already have an 80% sourdough starter. How do I get mine from 100% to 80%? Next time I feed, do I just start adding 100% flour and 80% water from then on and my starter will eventually adjust itself? Or will that original 100% keep the mixture slighty off that 80 percentage? If I'm thinking correctly, that would be 130% water and 150% flour making an overall 87% hydration, not 80%. I guess what I'm asking is do I ignore the percentage of my seed starter when calculating how much flour and water to add to it to turn it into 80% hydration? I'm so sorry for being dense....I guess I just need it spelled out for me.

You've got it right.... From your figures, I'm assuming you are planing on feeding your starter with 1 part starter, 1 part flour and 0.8 parts water?

What happens is that with each feeding the amount of water/hydration changes, based on a combination of the existing hydration and the new hydration. You got the math for the first feeding right, let's carry it through to the 2nd feeding.

Assume we start with 100% hydration, so we have 100g starter, consisting of 50g flour, 50g water. We add 100g flour, 80g water, so we now have 150g flour, 130g water, for a hydration of 130/150=0.87, or 87% hydration. In 100g of 87%hydration starter, there is 54g flour, 46g water. For the 2nd feeding, we add another 100g flour and 80g water, yielding 154g flour, 126g water, or 82% hydration. 100g of this starter contains 55g floyr, 45g water.

100g of an exactly 80% starter would have 55.56g flour, 44.44g water. I'm certain I can't measure well enough to be sure my supposedly 80% starter wasn't off by a few percetage points either way.

If you switch to adding 100% flour and 80% water it'll quickly get to close enough to 80% hydration it shouldn't be a problem.

You seem to know how much water and how much flour is in your current batch. From this information, there are a couple of ways you can get to your target percentage. The most simple is to base everything on the amount of water.

Example 1: If you have 200 grams of starter, and it's currently at 100% (half water, half flour) you have 100 grams of water, and 100 grams of flour. If you want to get to 80% hydration (that is, 80% total water), you need to increase the % of flour in your mix. Your next question should be - but how much flour should I add? Well, if you have 100 grams of water, and that should be 80% 0f the total (by weight), the total flour should be 125 grams. You find that by taking the water grams (100) and dividing it by the target percentage (80%). That is, 100g divided by .80 = 125g. Keep in mind that you already have 100 grams of flour in the mix, so you need to ADD 25 grams (total of 125 grams less the 100 grams you already have).

Example 2: You have a different, "less even" amount - say 528 grams of 100% starter. That means you have a container with 264 grams of water, and 264 grams of flour. Using the same method, if your target is an 80% starter, divide the water weight by the target percentage. 264g divided by .80 = 330g. Since you already have 264g of flour in the mix, you need to increase it by 330g - 264g = 66g. Again, the final target less what you already have.

Hope this helps.

Thank you all so much, you can't understand how much this helps..for awhile there, I thought I was taking crazy pills. Finally, it has seeped thru and taken root in my brain. Math has never come easy, but I will not let it stop me in my quest for great bread! And Rolls, thank you for introducing me to wildyeastblog.com which I discovered has an awesome recipe for sourdough pancakes!!! B-fast is served!

anytime

Unidentified Fermenting Object, that is.

I acquired some starter - it's very, very wet. Like cake batter. I'm not interested so much in firming it up as I am in just using it 'as is.' It's a pale yellow, so I believe it's been made on unbleached AP flour (I got the starter from the bakery at Whole Foods). In truth, none of the recipes I've looked at really talk about if the starter they are talking about is 'wet' or 'firm' for the most part - so I'm curious how you know how much to adjust the water within the actual dough to make up for the difference in a starter? Just by feel? Hold some water out until done with mixing and try to knead it in if the dough is too dry? Put it all in and just add flour if it's too wet?

Reinhart is not at all helpful at points. In one recipe I looked at, he gives the instruction that it should 'feel like French bread dough' - which is only helpful if you've made French bread!

I feed my starter on a feel basis. I never bother weighing starter feed. The % moisture in your flour will vary with humidity anyway, and the "right" hydration in bread dough will depend on the exact characteristics of the flour. A professional baking instructor whose passion is sourdough told me that while you should weigh out your ingredients generally speaking, you need to be flexible with exact water per cent because of those variability factors, and once you have a feel for it you should adjust to suit. Maybe I'm taking it too far, but this makes me pretty comfortable in keeping starter and levains and doughs in the ranges I want based on: feel only in the starter, then weighing plus adjustment-by-feel in the levain and bread dough.

I doubt any lactobacillus or C Milleri ever read up on percentages. Sure, slightly wetter or slightly stiffer will change the way they behave a tiny bit, but not so much as all the other variables in a domestic baking situation... (shut the fridge you kids, or oh look at that, it's 28 degrees C in the house today and was 22 deg yesterday, etc, etc). ANd while using an exact number might give more consistency even if all those factors were constant, why 70% instead of 68.343 per cent? And 100% is just a number in an infinite spectrum, why not 97.9952%, or 102.559%?

I'm very new at all this starter stuff myself, but I've made some nice loaves in the past few weeks and my suggestion, sulablue, would be to take your UFO starter..just a bit, maybe 30grams ..add 60grams each of water and flour and leave for 12 hours. If, after that time it's doubled - repeat. Feed twice a day for couple of days and if it's doubling for you, then it's ready to use.

Just my newbie opinion..there are loads here with years on me :)

Jackie,

Thank you but that wasn't quite the problem :) The 'UFO' meant, simply, that I'm not privy to what went into it. I KNOW it's good. I got it from a local bakery that used it for today's bread and gave me some after feeding it this morning.

My question comes in dealing with recipes from, say, BBA that use a much firmer starter. How does one go about adjusting for this if they aren't aware of the hydration of the starter - and I'm guessing, from other things I've read that 'just guess by feel at the end' is probably the only real way to go in the end.

The second starter I have is a spelt starter which is young, but doing alright. It smells like beer and is very mildly bubbly. Mostly it just has a foamy marshmallow like consistency to it when I stir it. This is the one that I'm going to have to nurse - but at least I know exactly what's gone into it, and at what quantities.

I think that you can adjust your starter to whatever hydration you need without worrying what it was originally at. I think the starter will adjust itself over time (if I understood the above correctly). So, if you need a firmer starter, say, 60% and you have no idea what yours is at, start feeding it 60% water and 100% flour and after 3-4 feedings, it should adjust itself. I think..... Sorry if this doesn't answer your question..

Also, does a "ripe starter" mean that it has reached it's peak of feeding and will soon start to deflate?

This makes sense, actually. Thank you.

I don't know if 'ripe' means it's about to deflate or no. I got the impression from reading wildyeastblog.com that 'ripe' meant that it was at the peak after a feeding though, yes - that the flavor would be best at... I think it said 8-12 hours after a feeding?

If I may take a slight tangent from this post....

My problem is not changing one hydration level to another -

My problem, which I now see as the "Murphy Law of Bread Baking" is that whenever I have a stiff starter going, I will ALWAYS find a bread recipe that I want to make right away, and it calls for a liquid starter.

Of course, as soon as I have my liquid starter ready to go, you know what happens....

I know that I could do all the calculations to use whichever starter I have in the recipe, but it's so much trouble, I am usually too lazy and just pick another recipe. But it is a bit irritating to have this happen all the time. :-)

The answer, of course, is to have 2 starters going at all times - one firm and one wet!

I might just start doing that!

Would it solve your problem if you were to keep 100% starter at all times and convert small quantities of it to lower hydration as you go and the recipe calls for. I believe it would not take more than the overnight fermentation, to have your firm starter ready for the making of the morning dough.

Just a suggestion.

Gosia

My understanding is that your starter percentage doesn't make all that much difference. It becomes the percentage you feed it with. After a few feedings it's whatever you want.

I've tried having a couple of different percentages of starters going, but unless you do an awful lot of cooking, it results in a lot of waste since you're feeding them twice a day on the off chance you may need one of them. I've been using the information in this thread and just keeping a 100% starter. Then I just adjust the recipe starter up/down for the difference and it's working very well.