Peter’s Blog, Sept. 15th, Cold Fermentation
He’s raised an interesting question: does long, cold, overnight fermentation create a flavor that would universally be considered superior; that is, an inarguable benefit? To answer this, I think, requires more than a simple yes or no, but an explanation as to what happens during the fermentation stage that would lead to the opinion that this is a way to improve flavor. We’ve discussed this here in the past, though in an abbreviated manner, so let me draw it out more completely and, hopefully, address Scott’s question at the same time.
My belief (and remember, this is just my opinion — no one owns the whole truth in these matters) is that the key to the value of long fermentation is the enzyme activity, in particular the alpha-amylase and beta-amylase action that slowly releases glucose, maltose, and other sugars from their starchy chains in the flour. This takes time, anywhere from 6 to 12 hours minimum, but it is not a biological fermentation since enzymes are not alive, they are simply part of the grain (protein fragments, but not living organisms, if I understand the chemistry of them properly, but then I’m no chemist). The process of sugar break-out from the starch is slower at colder temperatures but is not subject to the same rules as yeast and bacteria (which essentially go nearly dormant when they get cooler than 40 degrees F.). Anyway, pizza makers have known for a long time, whether by accident or intentionality, that their dough balls are better tasting and more beautiful to look at when used the following day (or even over a number of days, within reason) than if used on the same day in a fast rising method. It is not only because the fermentation is better in the slow method but, I believe, because more natural sugar has been evoked from grain by the enzymes and that improves both color and flavor, as well as providing new, ongoing food for the yeast and bacterial fermentation (so, in a way, it does elicit more fermentation flavor as well as releasing sugar). Bottom line: yes, Scott, I do believe long, cold fermentation improves flavor but, I have to say this too, it is not the only way to release flavor — that is, it is time more than coldness that is the key.
I say this because, as we discussed in the long comment thread a few weeks ago, Philippe Gosselin (and I’m sure others) uses a method that doesn’t require any yeast during the overnight period and, more importantly, pizza masters like Chris Bianco are able to achieve amazing flavor and texture by making their dough on the same day, not using any refrigeration. But in Bianco’s case, and others who can pull it off, the dough is made early enough in the day to allow the enzyme activity to occur without over-fermenting the dough by using a smaller amount of yeast. In other words, the “baking triangle” consisting of time, temperature and ingredients can be manipulated in many ways to achieve great results. Some methods and formulas might, for example, use a pre-ferment like a biga, poolish, or pate fermentee’ to add enzyme-evoked flavor in a shorter period of time.
So, to summarize, Scott123 is correct in asserting that long, cold fermentation achieves superior results to short, fast fermentation but let’s not forget the possibility of long, room temperature fermentation too, or the use of pre-ferments to shorten fermentation time (I won’t even touch the matter of commercial dough conditioners that spike the dough with added enzymes to speed things along — that’s another can of worms but one worth visiting in the future). If I’m not mistaken, Jim Lahey uses the room temperature method in his so-called “NY Times French Bread” method (and I believe also in his pizza dough — BTW, I think we should stop calling it the NY Times method and let Jim have it named after him, the Lahey method — I’m okay with that since he’s the one who first brought it to light and Jim is a good guy!). The fact that his French Bread dough sits overnight before going into a hot Dutch oven is for convenience more than because it is “overnight” — you could mix it in the morning and bake it at night just as easily; it is time, that very critical point on the baking triangle, that affects the flavor, as long as it is properly balanced by the other two corresponding points (ingredients = small amount of yeast; temperature = either cold or, possibly, ambient room temperature). For a pizzeria, though, it makes sense to work a day or two ahead for any number of reasons and, from what I observed at Pizzeria Bianco, it may simply be a matter of lack of space and refrigeration that necessitated the ambient method rather than a philosophical or anti-cold fermentation dough method. That is, we can almost always make the situation work to our advantage if we keep the three points on the “baking triangle” in the proper balance.
Okay, that’s my take on it — what do you all think?
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Peter,
Your statement: “…as the lactic acid bacteria (LAB)continue to work on the dough the more chance of dough structure degradation due to the acids …” stimulated me to go back to the books and try to uncover the root of the gluten degradation process. You suggest that there is a mechanism that is driven by lactic acid, or at least acid, and I am unable to find any definitive reference that attributes gluten degradation to acid. In fact, everything I searched for looped back to protease activity or glutathione as the source. I am open to acid playing a role, but I can’t find any peer reviewed papers that attest to that as a fact. If you can point to something authoritative I would like to read it but until then I have to go with the hypothesis that gluten is degraded by the activity of glutathione and proteases.
I did find some data (peer reviewed) indicating that protease activity does not decline as fast as yeast growth rate as the temperature declines.
Acids play a crucial role in gluten degradation:
http://microsour.com/pdf/4-gluten-hydrolysis.pdf
“Thus, hydrolysis of glutenins is mainly dependent on the pH and was not related to specific proteinases of lactic acid bacteria, in accordance with previous observations that wheat proteinases that degrade gluten proteins have their optimum activity at pH values of
…less than 4.0″
ie the proteolytic action of LAB is minimal compared to that of cereal enzymes already present in the flour but LAB fermentation provides the optimal acidic environment for those enzymes to hydrolyse gluten.
@TonyC
Thanks for the reference. That is a great piece of work that I had not come across previously, and it addresses a lot of issues beyond the role of pH (not total acid) in degradation of gluten. I have added it to my library. So we should expect gluten degradation to be more extensive in sourdoughs than in non-acidified doughs. It is not the acid so much as the acidic environment that facilitates the proteolytic activity that is naturally present in wheat doughs. The pH