Understanding culture elaboration
In BREAD 2nd edition, p148-149, he discusses the process for scaling up your starter significantly (aka, "elaborating" your starer). He offers a pseudo-scientific explanation for why this is optimal for the yeasts and bacteria in the culture, which, OK... sure! If it works, it works.
That said, I'm curious if anyone has had any experience -- or can offer a better scientific explanation than he does -- for why the two-step process he describes is actually necessary? The example he gives of how to get from 1lb mature culture --> 8lb --> 16lb mature culture entails mixing a first stage of 1 : 3.12 : 3.9 (mature starter/flour/water), letting that sit until it's ripe, and then adding additional flour/water, this time at a 8 : 3.55 : 4.44 ratio. Or, if you prefer the starter in the ratio to always be 1, that 2nd feed would be a 1 : 0.44 : 0.56
The takeaway from this example, for me, is that "when it's ripe, it's ripe." The fact that he uses such wildly different ratios in steps 1 and 2 doesn't do much to convince me that this multi-stage process is actually necessary. Could it really be the case that 1 : 3.12 : 3.9 is a fine ratio, and that 1 : 0.44 : 0.56 is also fine, but that 1 : 6.7 : 8.34 -- which is how you'd get from 1lb mature starter to 16lbs in one step in his example -- is not?
Thank you in advance for schooling me on this, if in fact I've totally misread the implications of this section of the book!
I think he is speaking from experience, although he himself reduced the 2-step elaboration from Calvel (who reduced it from the traditional French 3 step elaboration to the modern 2 step elaboration) to one step-elaboration himself when he created his recipe for Vermont Sourdough Bread, where he builds his culture by feeding it 1:11 and letting it stand for 12-15hrs in a relatively cold place.
Even then, the dough begins to recede at 12hrs mark and needs to be punched down if it is not time yet to mix bread dough, or else the gluten will reach the limits of its tolerance to stress, weaken significantly and will spoil the bread dough.
The issue is the same with the bread starters, they are sometimes created in one step process, like mix flour and water and let it stay untouched for days, then come back to the ready starter. Here inoculation is not just 1:15, or even 1:150, it's unimaginably smaller, because there are so few of those useful to us microbes in the flour or on the surface of the fruit. They grow from undetectable amounts to billions of cells per each gram of flour in the ready to use starter. In one step.
Sometimes it's daily feedings or even every 2-3 hours feedings are prescribed to create a starter from scratch. Some feedings are 1 : 0.5, yet others are 1:10 which was experimentally established as the safest limit. I tried them all and they create different starters. Among bakers there is this opinion that smaller feedings, more frequent refreshments, are safer for the culture, they preserve it better, and create more flavorful outcomes.
The smallest ratio I saw as recommended by a professional baker about 10 years ago is 5% inoculation, feeding 1:20, it still safely preserves the culture from being overwhelmed by the microbes from the flour itself. Although not for long if you feed it with whole grain flours. The culture will change eventually. So such feedings are left for an occasional starter storage, not for building levain for baking per se.
These days microbial cultures for sourdough can be bought and deployed within hours, so preserving something carefully is not so important for the steady bread production for sales, while preserving trademark flavors of bread, therefore we can relax a bit and explore one step methods.
Maybe there is something I need to learn (and happy to do so), but my approach is very simple. My starter is active. The only reason that I would make more than one build for a levain is because I don't have enough of my original culture to build the required amount of levain.
As far as feed ratios during levain builds --- if I want it quick levain the feed is 1 to 1 and it proofs for 4 hours at 80F. If the levain needs to ferment longer (for convenience), maybe overnight, the feed ratio is increased and the ferment temp is much cooler.
Most experienced SD bakers will tell you that starters are not fussy. They are resilient and easily altered. That has been my experience. As an example, my white starter is often changed to a whole rye or whole wheat starter is a single feed. It readily eats whatever is offered.
Well said Danny, too many bakers try to over complicate the process.