I've read somewhere that you can calculate extended rise time with the following:
amount of yeast for original recipe * rise time for original recipe = amount of new yeast * rise time for extended modified recipe
So for grams and minutes it might be something like:
5 * 60 = new yeast * 120 where a doubling of rise time would use half the yeast at 2.5 gr.
My question concerns which rise time? I imagine it is bulk fermentation but does that mean that after shaping proof time would be same as original?
How about when a starter, biga, poolish, or equivalent is involved? Does that yeast get modified too?
thx
Dan
...I don't think it's linear. I recently reduced yeast in a recipe by 1/3 and saw no real change. The next day I cut it by half and saw bulk rise times increase from 45 minutes to 60 minutes.
FF
Doubling time for yeast is a function of temperature (hydration, sugar content, salt, acid, and a lot more). At any given temperature the doubling time will be relatively constant for a given yeast.
A fair rule of thumb would be two hours to double at 80F. So if you halve your yeast you need about 2 hours to get back to where you started the other dough and another hour to get to the same point as one hour on the original - so you need to jump from one hour to three hours - two will be underproofed. But that is only an estimate. Reality will likely be different.
Sure enough, it was here at TFL that I read about the formula and was from Norm, an authoritative source as he was a professional baker for many years. Check out the link below.
http://www.thefreshloaf.com/node/10876/long-slow-bulk-fermentationplease-critique-recipe#comment-58448