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 But the difference between 17% and 20% is nothing at all and can be put down to difference in starter speed quite easily. Then you have to take into consideration the length of fermentation for the starter. Most people recommend using the starter when it peaks.

Notice that for 50 F you have to use a lot of starter for an eight hour 'fermentation' I use inverted commas because at this temp it's really a rest rather than a fermentation and I wouldn't use this data for making a dough. But there are recipes out there for this amount of starter, so take your pick. Okay I've probably gone way too far answering part of the question. The short answer is use as much or as little as you like. I prefer to use very little starter. I'm making a loaf at the moment, I started last night using just 14g of starter for 550g of flour just 2.5% a bit more than the salt quantity. It is fermenting out on the counter and will be ready to shape when I get home.

Jim

I don't know if this will help or not but it will work and get you started without all the calculations.

Starter - Use 100% starter and refresh by tripling it. (i.e. 100g starter, 100g water, 100g flour)

Bread - Use enough starter so that 20% of the total flour comes from the starter. If your total flour is 500g, use 200g of starter (which contains 100g flour) and 400g of new flour.

For example if want to make 1000g of dough at 65% hydration using 100% starter.

This means the final dough will have 100 parts flour and 65 parts water for a total of 165 parts. So the flour will be 100/165 times 1000 = 606g and the water will be 65/165 times 1000 = 394g. Now you want your starter to contain 20% of the total 606g flour = 121g. So use 242g of starter (121g flour, 121g water) and just subtract these values from your totals like so:

Flour = 606 -121 = 485g

water = 394 - 121 = 273g

Starter = 242g

Salt = .02 X 606 = 12g

OK, you're right Jim.

How about this simplicity. For making dough at 65% hydration using 100% starter (from above), 25% of the total weight should come from the starter.

I think I'm beginning to understand that it is dependent on various things: the hydration of your starter, the organisms in the starter, the temperature of the dough, etc. The number of organisms in your starter is what you should be looking at, which would be somewhat proportional to the amount of flour in the starter, when the starter is very ripe, that is. So if Jim is using a 2.5% inoculation, he has calculated that the temperature and inoculation allows a certain amount of time for fermentation, which could be a relatively long time compared to what, say, Hamelman may claim in his recipe--haven't read it, but he might say something like, "let ferment about 4 hours, until doubled in volume." And perhaps Jim wants his bread to have certain characteristics that result from those temps, times, etc. Regardless, though for some reason I can't see the graphs he posted, they should be helpful. Inoculum amount B (flour amount in starter) will increase B amount of flour in time t at temperature T. At 2t, the total amount of organisms will be proportional to 4B in your dough. Be kind enough to let me know if i'm off on this.

EW

I've been struggling with these same questions, too. There are various strategies to try to run the various fermentations to get flavor. Some emphasize the flavor in the starter and preferment. In that case, I think the idea is to get a flavorful, maybe more sour preferment, which flavors the rest of the dough. In that case, the starter or preferment that is included in the final dough may constitute a fairly high percentage and is the main contribution to the flavor of the bread, so that the subsequent bulk fermentation would be mainly just to raise the bread and not so muich for flavor and would take less time.

Or as in one of the posters above who generally prefers a much lower percentage of starter, you could have the sour flavor develop in the dough itself, but then you might want to run a much longer rise possibly at a lower temperature, allowing the flavors to develop while the yeast slowly grows and begins to raise the bread after a much longer time, say 24 hrs.

I think these are two prototypical strategies, and one could imagine any number of ways of then combining these. There are a number of constraints, like the gluten has to hold up as the acid levels rise in the dough, the sour flavor can't become too strong and therefore unpleasant, the nutrients that keep the bread rising can't run out before the bread finally is ready to go to the oven, and so on.