The Fresh Loaf

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High Hydration Boule: Explosive Fermentation (and size)?

Gadjowheaty's picture

High Hydration Boule: Explosive Fermentation (and size)?

Hi All.

Playing with different hydration rates, to get a loaf I'm really happy with.  Very puzzled by my latest loaf:

Levain Boule - high hydration














Levain boule, crumb -12/15









(clothespin for scale).

-as the size of this monster is through the roof, comparatively speaking, and the fermentation was much more explosive than previously; with the only variable I've changed, beside more time for this starter,***was a slightly higher hydration rate in the finished dough. 

You can see from the pics, while the crumb has, to my eyes, anyway, a nice mix in terms of openness, the loaf profile is very flat.  In truth, all the way through the bulk ferment/folding, to placing the dough on the peel, the dough was very, very "flabby," for want of a better word (I'm sure there's a baker's term for this).  I am confident this isn't due to a lack of gluten development, but would strongly suspect the hydration rate - is this a correct assumption?

Here's the particulars:

Refreshed the starter with 2 tbsp starter, 1/2c water, 1/4c white whole wheat (I'll call it "WWW") flour, 1/2 cup KA bread flour; allow to ferment to 12 hours, feed again, yielding an active, 100% hydration starter.

Day 1 of dough, 1 cup of this starter, 1c/5.5oz KA bread flour, 1.250c/10.4oz water; ferment for 4 hours.

Mix in 29.3 oz. KA bread flour, 3.7oz. WWW, 2.125c/17.7oz. water.

Rest/amylisation for 30 minutes.  Add in 2 tsp. salt, french fold/knead, bulk ferment 5 hours, folding every hour. Shape into boule, placed in floured banneton overnight, 12-15 hours.  Temper for 75 minutes (with other loaves, I temper up to 2 hours, or until 75% bulk; because this dough was going into the banneton already quite expanded, I didn't want to push the tempering time before baking too much).

I get a starter hydration of 101%, poolish hydration of 188%, final hydration of 76%.  Originally, I was getting 151% poolish, and about 70.7% dough hydration, but I wanted a wetter poolish, and to experiment with an overall higher hydration on the finished dough.

Previously, the dough went into the banneton considerably smaller in size - the bulk ferment yielded nothing like this size, and the finished loaf, even with a longer tempering post-retardation, was considerably smaller (about half-volume, by memory); but interestingly, the previous loaves had a much, much higher vertical spring (most of that, it seems, from what folks were saying, was apparently due to my baking the loaves right from retardation, without any tempering/final proofing). 

Any thoughts as to whether the hydration is the key, both to the explosive growth, and the lack of "hold" to the dough, and vertical spring?

Not really disappointed - the bread is really, really chewy (I like it like this), well-developed crust, and delightfully sour.  The only visual I'd hope for would be a bit higher loaf, but I guess, anticipating answers, I expected this, with this level of hydration.  It literally poured out, moved like a blob, on the peel, and it was a dash to slash and drop it on the stone, to attempt to slow the outward movement.  Perhaps a lower hydration?  Different slashing technique?  Different flour, or some wheat gluten?

Thanks for any thoughts, all.


***Meaning, to me, anyway, more "teaching" of the yeast and bacterias to undergo, and complete, the fermentation least from my brewing days, something I learned is that younger yeast will start off like gang-busters, but will typically peter-out when it comes to finishing off the last bit of available free sugar, or chewing off the longer or more branched chains of available complex sugars, to "finish," or "attenuate" the beer...successive generations of propagation/pitching/fermentation always prove better "finishers," up to a certain generation cycle, at which time the population tends to tire, requiring a new master inoculation/propagation, etc.  This was my experience, anyway.


Postal Grunt's picture
Postal Grunt

From what I recall of my homebrewing beer days, the different strains of yeast had their own individual levels of tolerance to alcohol before their effectiveness ceased. The British ale yeasts seemed to be the hardiest with high gravity beers but even they lost their ability to work at around 8-9% alcohol. Many microbrewers have been known to finish off their high gravity beers such as barleywines with a secondary pitching of champagne yeast that can be effective up into the 12-14% alcohol range.

Perhaps what we perceive as a tired teast is only a yeast that has reached the point where the small levels of alcohol produced by the fermentation of the bread have reduced the effectiveness and maybe even viability of some of the yeast cells. Given the varying descriptions of the more popular sourdough strains where some are described as vigorous and others bestial (sp?) when another is considered moderate, there may be some foundation to my speculation. I'll bow to the more learned on this topic when they add to this thread.

Well seasoned and floured holiday wishes from the western bank of the Missouri River


Gadjowheaty's picture

That's a consideration, PG, to be sure, and you're right - there are strains that are known to be "high attenuators" relative to their s. cerevisae cousins.  Please forgive the redundancy if the following is known to you or others, or the boredom if it's unknown but eyes gloss over nonetheless to the technical babble which follows, but I do hope some may find it interesting:

Beyond the relative apparent attenuation of different yeast strains, even within a given yeast strain (or mix of strains, and bacterias, as with our sourdough), the yeast population can be induced to "finish" or attenuate a beer, by several things.

Right off the bat, the mix of sugars in the wort (or whatever fermentable we're dealing with) will encourage either a higher or lower apparent attenuation. Depending on the relative concentrations and preferential activity of alpha amylase (randomly cleaving "dextrin limits" from maltose, and making "non-reducing endpoints" available to beta-amylase) and beta amylase (serially chomping on the gluocse chain end-points only, producing maltose), one will get a higher or lower concentrations of dextrins and maltoses.  I never did it, but there are even additive enzymes, to get a beer even lower - all kinds of "-ases." See here, for instance, for some witches' brew of enzymes some of the mega-producers may use (to make higher alcohol, "thinner" brews).  These are exogenous additives, but as you may know, all kinds of things - temperature, pH, even mash thickness and malt crush - will encourage either alpha (branching enzymes) or beta-amylase (end point enzymes) from doing their job.  (If interested, just came across this - see here, for a brief further discussion of brewing enzymes and starch conversion).

Turning to the subject of the thread, however, my question actually goes to a difference between 2 loaves, given the same strains of wild yeast and bacterias - the same population of fermenting critters creating a different result, not 2 different strains producing different results. This kind of stuff, I find fascinating - as with brewing, when you have a biological product, an inherently variable, living thing; analyzing the differences between batches, given the same parameters otherwise, or trying to isolate a causative variable (as here, when I conjecture the hydration level).

I did raise the notion of "teaching," only because it's what I saw on a working basis in the brewery I worked for; beyond enzymatic activity and "engineering" relative sugar concentrations, a given population can be "taught" to finish beer more properly, chiefly by allowing the yeast to do its work, fully, up to a certain critical generation - at the brewery, we monitored each batch (4x50bbl batches to fill a 200bbl fermentor) with something like 20 quality control points, and among them was just this kind of analysis - which generation off a master batch of (20bbl) yeast propagation we were dealing with; and how well and how quickly the population attenuated, reached final gravity. 

Just came across this, by way of example - I always liked White Labs' products.  Their "WLP820," the "Oktoberfest/Marzen" apparently takes a generation or two to "kick in." Wyeast has a similar thing - a brewer asks why his or her beer isn't attenuating, and he or she is asked "what generation are you on?"

Anyway, sorry for the long brewing technobabble; I do hope some might find it interesting....a former student of malting and brewing and practicing brewer, among other things, the science behind fermentation is something I lived with for quite a while, and touching on the subject of this thread, I do find it interesting - why do batches behave differently, given the same population of fermenting beasties?

PS:  Sorry, but find this fascinating...a study I just read concludes by dismissing the effect of serial regeneration on fermenting performance - "attenuation half time" and sensory parameters unaffected by serial the brewery I worked for, we used to re-master after 12 generations, I think it was.  This article suggests this widespread practice is more a dogma or tradition, than anything based on empirical science. The article concludes:

With respect to serial yeast repitching, it was evident
that reuse of the crop up to 13 times did not affect the
fermentation as evidenced by the parameters measured.
Although routine sensory analysis was not designed to
detect an effect of yeast repitching, no effect of repitching
was noted on the flavour of the brand. One could conclude,
as have past studies4,6, that serial repitching does
not inevitably lead to reduced strain performance. Powell
and Diacetis4, when discussing the successful repitching
of a lager yeast crop 135 times, concluded that "...the
effects of genetic variation were diminutive and not of
significance to the production of beer". Their conclusion
supports our findings. Large brewers may find it worthwhile
to re-examine the current practise (perhaps dogma?)
of discarding their yeast after 10 fermentations.

(Warning: pdf).

<<sorry for the side-journey, again!>>


Postal Grunt's picture
Postal Grunt

Thanks for posting your reply. Obviously, you enjoyed that job.

I still miss homebrewing because it was more than just opening a kit, boiling water, pitching yeast, bottling, and then enjoying the fruits of my labors. While there was a lot of craft involved, the longer I brewed, the more I delved into trying to understand the process, the ingredients, and the business side realities. Unfortunately, I got to the point where I realized that the only way to get better was to get bigger, make more batches, and take the fun out of it by spending all my free time on and money on brewing because my friends weren't interested. One friend was in AA and the other was into Dewars scotch. It was starting to become work.

But now I get to play around with yeast again and I've never seen anybody post here that a cop pulled them over for driving under the influence of a sourdough rye, Maybe what went around did finally come back around again in a better way.


Well seasoned and floured holiday wishes from the western bank of the Missouri River. PG