December 22, 2012 - 10:41am

## starter build maths

here is hoping i did the maths right - i need 100g of starter @ 100% hydration.

please could anyone check it for me.

thanks - John.

take 20G of starter @ 60%hydration. then add 50g of flour and 55g of water and let it double @100%hydration at 70f.

sounds a bit strange to me.

If you have 20g starter @ 60% hydration, that's 7.5 g water and 12.5 g flour. Well we can round it up to 12 g flour and 7 g water (half a gram water would most certainly have evaporated while you're handling it, anyway).

You need 100g starter at 100% hydration - that's 50 g water and 50 g flour.

Therefore you need to add (50-7=)43 g water and (50-12=)38 g flour.

... that's unless you want to have 100g total, as opposed to, use 100 g and keep some. In that case you could say add 53 g water and 48 g flour and you'd have 120g starter at 100%, use 100 g and retain 20 g starter @100%.

ah you wanted to end up with 125 g starter total, sorry I missed that. In that case you're right :)

Thanks for checking.

John

Looks good to me.

Thanks for checking Polo.

my next task is to build a spreasheet that calculates how long a sponge mix will take to mature.

i mature my sponge overnight, but what would the best maturing period be?

any ideas?

John

Can you tell me the components of the sponge as well as their amounts.

here it is - i normally give it 8 hours overnight at 70f-80f to ferment.

Well I don't know the rising habits of your starter, but I will give you my uneducated opinion. You are feeding your sponge at a 1-2-2 rate (1 part starter, 2 parts water, and 2 parts flour), if I were to feed mine at that rate and keep it at that temperature, I feel that it would be past its prime after 8 hours. If your starter is past its peak after 8 hours at that temperature, then I feel your sponge would be past peak also.

Since I am making such a large amount, I build mine in two stages and I build it at a 1-4-4 rate. I know that my starter will be short of its prime after 12 hours when I feed it at this rate, so I can plan my schedule around that.

For instance, this morning I started with 48 grams of starter and fed it 192 grams of flour and 192 grams of flour (432 grams). This evening I will increase this sponge by feeding the 432 grams I made earlier with 1728 grams of water and 1728 grams of flour. This total amount (3,888 grams) in turn will be short of peak in 12 hours if kept at 68 to 70 degrees. I definitely rather use the sponge while it is immature, but only by an hour or so. I will use the 3,888 grams of sponge to make 48 lbs. of dough tomorrow morning and bake tomorrow evening. Oven is being fired as a preheat now, kind of cold here.

No retard this time around, I ran out of time :(

Mark

Hi,

70f - 80f is quite a large range! I would argue that 10f make a difference of a few hours easily. To be more exact about it you can take flour and room temparature into account so you can calculate the water temperature (since that is the only one you manipulate):

The formula goes like this:

(4x desired temperature) i.e.: 280f

- flour temp -65

- room temp -68

- starter temp -68

gives you the needed water temperature: 79

More here: http://www.thefreshloaf.com/node/22008/dough-temperature

100g starter to 200g flour is a lot and I agree with the other poster that I would assume it peaks in less than 8 hours. For this time I usually go with about 30 - 40 g of starter for 200g of flour. It largely depends on the temperature and the activiy level of your starter, i. e. has it been fed every day or does it just come from 1 week in the fridge.

Hi,

I agree the temp range is quite large. I use my airing cupboard to proof / mature my baking. The temperature range is normally towards 80f, but during the night it drops towards the 70f mark.

I have followed the link you suggested and I will read through it carefully. I am a bit slow on the uptake and may need to ask you questions after I have read it - hope its OK to message you.

I normally use a jug with a thermometer to get the water temp to exactly 70f.

I have had problems with the potency of my starter. I was storing starter @ 100%, I was having problems with alcohol. I now store 80g of starter @ 60% in the fridge. I carry out 2 builds to get to 100% prior to making the sponge.

My starter is now very potent and I think I can drop the amount I add to the sponge. I can experiment with making sponge and checking timings.

I'm hoping that with all the talk about HYDRATION some one here might help me. I want to know what hydration level my starte is; when I feed/refresh it I take 16 oz (1 lb) of starter and add 8 oz flour with 8 oz (1 cup) water. In fact it's from Peter Reinhart's "Bread Baker's Apprentice," page 232. Given those ingredients, what is the HYDRATION please?

Bruce

Brookings, OR

If the 1 pound you are starting with is made of the same ratio, then your starter is 100%. Equal weights of flour and water would equal 100%.

Grams Flour Grams Water = Starter Hydration

100 100 100%

100 90 90%

100 80 80%

100 70 70%

............and so on