Effects of fermentation and soaking question

If I can say it without sounding like a smart-aleck, how about doing a side-by-side of all three techniques (preferment vs. cold retarded ferment vs. soaker) and let us know what you find out?

I'm not really sure what your results might be, but I'd be interested in learning what happens.

Paul

and an invitation to discussion.

First, if you are not at least a somewhat consistent bread baker, just let me respectfully suggest that you are tying yourself up in knots with your questions.  There are many methods of producing bread and they will all have different results in your hands and under the conditions that you bake.   It might be best to pick a method and see how that works for you and then expand your repertoire.   There is no "scientific" explanation on all this as we are dealing with taste and handling qualities that are somewhat subjective.  This isn't formulaic.  Large scale bakeries will go to great lengths and run many analytic tests to adjust to conditions and flours, but we, as home bakers, must learn to respond to the demands of the living organism with which we work.   Anyway to attempt to answer your question. 

I'm going to assume (since you used "yeast" in your questions) that you are asking about breads with commercial yeast. Some of my answers would be different if we are talking about wild yeasts.

In general, the longer the fermentation time, the more "taste."  In theory, breads made with almost no yeast and fermented for very long times would be the "most flavorful."  However, there are tradeoffs that must be made in terms of time and space constraints (and how the gluten in the flour reacts to a very, very long fermentation) and a number of methods have been devised to coax taste from flour.

The poolish or biga (I prefer the term pre ferment) method takes a percentage of the total flour in the formula at a certain hydration, incorporates a small amount of yeast and allows it to completely ferment normally (not in a cool environment - usually at the ambiguous "room temperature") until it is ripe.  Ripeness is judged by the appearance/aroma of the preferment but is usually done "overnight."  So here is the first set of conditions - the amount of the flour that is in the preferment, the hydration of the preferment, the amount of yeast in the preferment, the ambient temperature and the time.  Pre ferments are generally not "retarded" - that is allowed to ripen in a very cool condition - although some people do it.  It is more typical to control the rate of fermentation in the pre ferment by varying the amount of yeast.

Now the question is how much flour to preferment.  I have seen formulas from very low percentages to very high.  When a very high percentage of the flour is pre fermented, the sugars/starches in the flour can be totally used by the yeast in the preferment and then some diastatic malt may need to be added so that the full amount of yeast in the full amount of flour can ferment properly. If too much flour is pre fermented and malt is not added, the resulting bread will not rise well. Perhaps that is what your author meant about "souring" the bread (or the author may have been referring to natural leaven breads - another topic.)

Once again, the longer the fermentation time, the more "flavor" in the pre ferment.

In general (although I know not always - so don't y'all pounce on me...) a bread that has a pre ferment then goes through a normal fermentation process.  It is not given retarded fermentations after mixing the full dough.  In theory this is because the benefits of long, cool fermentation have been obtained through the pre-ferment.  Or that's my story.

What does this do to the taste?  It adds the taste of long fermentation to some of the flour.  What does that do?  Well, pre fermenting a large percentage of the flour will add more "taste", but what I find is that I face tradeoffs in crumb structure with my hands and my altitude.  I tend to pre ferment a smaller amount of the flour than most folks and do a more thorough bulk ferment.  I have worked and tuned these factors until I have exactly the bread that I want (Note that I say "I want."  I am baking for me and a small group of folk who seem to like what I do.  Great tasting bread for me might not be what you want.  This is a subjective business.)  I make a formula, bake, taste, evaluate, take notes, and then tweak.  You will need to do the same. There is theory and there is practice.  This is a hands on craft.

The Gosselin Method as I understand it (and you seem to refer to it in many different ways) is an interesting variant.  It does a retarded partial fermentation with all of the flour and then adds additional water, salt and yeast.  This gives the benefit of a long, cool partial ferment on all of the flour. Note that I say "partial ferment "on all of the flour.  If a complete ferment was given to all of the flour, when additional yeast and water was added, there would be no food left for the yeast.  The bread would not require additional bulk fermentation time and would not rise well.  The cool temperature and small amount of yeast in this method is what drives the partial fermentation. More extensibility?  Probably.  More "taste"? Probably.  In your hands? You must try, bake, and taste. (So in terms of too much pre ferment souring the bread, the Gosselin Method does not actually do a complete pre ferment on all of the flour, so the bread should not be "soured.")

Mixing a complete dough (salt, yeast, and all) and doing a long cool bulk ferment gives the advantage of a long fermentation to all of the flour.  More "taste"? Most likely.  More extensibility.  Probably.  The presence of the salt will have an impact on how the gluten develops, but probably not too much.  This method has certainly been used with good success to give flavorful, very open crumbed baguettes.

And with that, we must consider the effect of the amount of yeast in the final dough - do we want maturity to occur slowly or quickly?  We can use a large amount of yeast and make a long fermentation by retarding the bulk ferment or we can use a very small amount of yeast and make a long ferment without retarding. Each of us has different constraints that will make different methods more desirable.  For example, I must produce bread from the mixing of the pre ferment to the cooled loaf in less than 20 hours.   My process has also been tuned for that.

(And no matter what, I will paraphrase what I have heard from no less a baking luminary than Solveig Tofte  - that getting an open crumb in baguettes is not a function so much of hydration, but of getting the fermentation correct.  In all these methods there is a factor of removing the bread from the particular type of fermentation involved at the correct time and degree of fermentation.)

When you talk of soaking all or some of the flour, you are talking about putting water to the flour in the absence of yeast.  This will allow the gluten to develop without fermentation.  This is often used with whole wheat flours - where it also softens the bran so that it does not slice the gluten strands.  It is used less often with white flours.  Soaking the flour is not a pre ferment.  It can be done at cool temperatures for exactly that reason - to prevent any wild yeasts from getting involved in fermentation.  So, soaking the flour is not really done with goal of adding "taste" - it is done with a goal of getting gluten to develop more thoroughly.  This may have more effect on bread volume than taste.

There are infinite variations and there is no "one true way."  Few of us on these pages have access to precisely controlled environments, but I will repeat my recommendation to try to bake the same bread a few times and only then evaluate and vary.  It is unfortunate that we do not have absolute consistency in terminology for bread baking, but sometimes we need to take a deep breath.  Learn to think in terms of the amount of flour that is pre fermented, the hydration of the pre ferment, the total hydration of the bread and the percentage of yeast in both the preferment and the final dough.  This is a very useful way to think about bread techniques and although some may have interesting variants, you can at least see those variants in the context of "normal" methods.

I hope this helps

I tend to look at all this from a very practical standpoint. so, here goes.

While understanding the theoretical of using  a small enough amount of commercial yeast and a long enough retarded fermentation to allow bacterial action, in essence what we are doing as home bakers is using a moderate amount of commercial yeast and a short enough cold bulk fermentation time (usually no more than 8-12 hours) that I'm just not sure this theoretical occurance has time to occur.  Add to that the fact that high hydration "sourdoughs" kept at relatively cool temperatures tend to encourage yeast growth (as I have been told and sort of expereienced) and we're into the territory of "maybe it happens" in my tiny mind.  Or am I completely off base here?

I'd agree that a yeasted pre ferment develops a flavor, but here we are talking about fermenting at "room temperature" (in general) for 8-15 hours and I'm not yet ready to sign on that it develops the significant lactic/acetic qualities that we would get with a levain.  I would hope that they would be different - because this allows us different taste profiles.  I've taken a liquid levain pre ferment and put it into a commercially yeasted dough.  This is a very different flavor than a commercial yeast preferment in a commercial yeast dough (and I did not find it to be my "best bread ever"...)  I'm open to convincing, but my baking to date does not do it.

I'll go down with the ship over adding a liquid levain or a 100% hydration preferment to the autolyse.  I've talked about this at great length with folks who ought to know what Calvel meant.  I'm not budging on this.  You can't autolyse the full amount of flour with the remaining liquid if you do a high hydration pre ferment.  You cannot.  The pre ferment must be added and it's no crime.  If you think it is, then you must make a firm pre ferment to use autolyse.  The Gosselin method (and I hope this thread doesn't get found on "the Google" when people really want to know about those folks with 8 kids) has a small amount of yeast in the full amount of flour for a long, cold ferment.  I'm not sure that is a real autolyse - but that's where knowing the baseline helps us think a method through.  The method gives a long, cool, but not too thorough ferment at a low hydration to all of the flour.  This flour will have pretty nice gluten development, but since the yeast is starting to drown in its own waste but hasn't completely used all the available food it is a good candidate to get some more water, some more yeast, some knocking about and it will work well.  It should have a nice flavor because of all that flour that was fermented so long and will have good elasticity for the same reason.

I'm also interested in the complete fermentation.  Yes, punching down a dough does re distribute the waste products and allow the yeast to grow again, but at some point, the food is exhausted.  We see this in over proofed dough - or dough that has had too long of a bulk ferment.  Doesn't matter what you do - the thing is not coming back.  I know that if I stir down a fully ripe 100% hydration pre ferment, I won't be seeing much more action from it.  Perhaps the difference in the hydration levels between the pre ferment and the final dough are the difference.  On a practical level, I have seen as much as 42% of the flour pre fermented in a formula.  If that 100% hydration pre ferment is mature, you have not much food left for the yeast in the rest of the flour.  Something must be added. Or so the baker says.  What am I missing here?

I'm not a scientist (although I are an engineer).  I tend to try to do "single factor" experiments (although, my baking has reached a point where I can consistently turn out the same bread with the same formula week after week) but I know if I were a scientists I would find them replete with flaws.  What I have found useful though is to set parameters: I need to get the baking done from pre ferment to cooled loaf in 20 elapsed hours.  I want to use natural leaven.  Then I establish my desired mixing technique - by hand.  By this very set of parameters I have eliminated certain techniques (reatrded bulk fermentation and pseudo Gosselin for example...).  Then the variables that I mentioned can be varied to design the bread.  As in any discipline if we leave things too open ended we can glide into the paralysis by analysis mode and neglect making excellent bread in the pursuit of "perfect bread" (and if "my teacher" heard me say that he/she would not believe it.  Perhaps my time at "the place" did me good, after all)  What I have focused on in my bread evaluations is to identify the probable source of the problem.  Insipid taste?  Probably a problem with fermentation.  If I was careful about my bulk fermentation, this is probably an issue with how I conducted my preferment.  If I know that it was ripe, I will try to vary the percent of flour that I pre ferment.  Just can't get the thing to hold its shape?  Well, if I've been careful at all of the other steps, perhaps I have pushed the hydration too high.  That's why I emphasize baking a single formula (even if it is sub optimal) until you have achieved reasonable consistency.  That way when you vary one factor you have the memory of how the thing has performed in the past and can judge if you are closer or further from your goal.  When that bread is consistent and if you want to "improve" it - then you can vary one factor at a time once again.  Bear in mind that because of the tender age that I started baking bread and my own "decrepitude" I've been messing with bread now for a half a century.  I won't say I'm an expert, but I've had a lot of dough pass through these hands and frankly that colors my thinking.

Jeez we can get going on this stuff.  :>)  That's why, while I won't cop to ignorance on a lot of these topics, I tend to endorse putting them to back of the mind and let the bread do the talking.  But it is fun to chew over some of the more theoretical...

It's true that there are bacteria that convert alcohol to acid. In the food industry the most common example would be vinegar (primarily acetic acid) is created by exposing alcohol to a specific acetic acid producing bacteria that "eats" ethanol. However, this is not the bacteria that is present in sourdoughs.

Some bacteria, just like yeast convert sugars into their respective waste products, i.e., CO2 and acids, CO2 and alcohol respectively. So some acid producing sugar eating bacteria may live side by side in some environments with some yeasts and compete for the available sugars. But eventually, due to different reproduction rates one species would dominate.

So how do sourdough starters continue to live stable lives for alledgely hundreds of years--if you believe the folklore? Therein lies the beauty of sourdough starters.

Sugar molecules aren't all the same. We've all seen, on food labels, words like fructose, glucose, sucrose, maltose, dextrose, and who-knows-what-ose. These are all different sugars, and their difference is evidenced at the molecular level. Rather then spend our time looking at the myriad differences, for this discussion it's important to know that some yeasts can't eat some sugars, and similarly some bacteria can't eat some sugars. If a particular yeast lives side-by-side with a particular bacteria, in an environment that contains sugars that each can eat, and each can't eat the other's preferred sugar; Eureka! we've got the Jack Spratt and his wife relationship. They can exist side-by-side, and lick the platter clean.

To get slightly more specific, from my Google derived reading--I'm not a biologist, neither micro nor macro, but I am a scientist, and I can read, and math is math--the most scientifically studied sourdough is--surprise, surprise--San Fransciso sourdough. The biologists have discovered the primary bacteria in SF sourdough is unique--appropriately, they included sanfrancisco in its appointed name, and it can, and does eat maltose. It's teamed with a variant of a relatively common yeast that can't eat maltose. Moreover, the SF bacteria produces other byproducts that prevent other organisms from living in the same environment--much like penicillin--that its yeast neighbor is immune to. There is a lot more going on too in a flour and water environment: e.g., temperature tolerance, pH tolerance, enzyme production, ionic bonding, and so forth; but this is the gist of their relationship: they can coexist, and so long as there is food for both, they coexist in a stable environment--for centuries, if you believe the folklore. So, simply put, we feed our starters, and keep them comfortable.

An aside: Subsequent reasearch has found the sanfrancisco bacteria in sourdough starters im many other places throughout the world, teamed with similar yeasts.

That is not to say there aren't other stable yeast, bacteria relationships in other starters, however, it is safe to say that to be stable their coexistance requires similar attributes.

David G