Omid, increasing the yeast count would alter the yeast:bacteria ratio, but I doubt it would reduce the number of bacteria meaningfully. They don't really compete much for food. Would this really reduce the acid production unless the increased yeast activity allowed you to shorten the fermentation time? Would you lose overall flavor if this is the case?
I wonder if you really wanted to give the yeast an unfair advantage vis-à-vis the bacteria if you would allow them to stay in the frothed state for some time before incorporating into the dough? Maybe even feeding them some of the formula flour right before frothing?
I started a batch yesterday employing your froth method (which I had not previously considred). I frothed the yeast with a hand whisk (worked just fine). I then added the rest of the water with the salt already dissolved. I then immediately incorporated the flour. I did this as gently as possible with a spatula and a folding motion to try to incorporate as much air in the dough as possible. I'm curious to see if I notice any difference.
Dear Craig, since the propagation and activities of the extant microflora in a sourdough starter are concealed from direct human perception, and since my knowledge of these microbial organisms is scanty, I am not able to indubitably answer the questions for you and for myself. Additionally, as revealed by various applied microbiology literatures, this issue is further complicated by the fact that different starter cultures are occupied by different species of lactobacillus bacteria and wild yeasts, each of which has its own peculiar growth and metabolic characteristics that make each culture different from one another. How can a layman, such as myself, identify the type of sourdough culture1
one has? Moreover, how can a layman identify the type of lactic acid bacteria2
and fungal micro-organisms that thrive in a culture? Given the scope of this difficulty, I, by necessity, rely on my repeated experiences and observations of these microbial phenomena, and I look therein for patterns and uniformities on which I can base my speculations.
1. According to Modern Food Microbiology, authored by James Monroe Jay, Martin J. Loessner, and David Allen Golden:
"Sourdoughs are placed into three groups and each has its unique fermentation consortium.
Type I sourdoughs are fermented at 20-30ºC [68-86ºF] and the two primary organisms are L. sanfranciscensis and L. pontis.
Type II [sour]doughs employ baker's yeast as a leavening agent, and the dominant lactics are L. pontis, L. panic[/i], and from one to nine other lactobacilli.
Type III [sour]doughs are dried products of traditional fermentations. . . ."
2. According to The Lactic Acid Bacteria: The Genera of Lactic Acid Bacteria, authored by Brian J. B. Wood and W. H. Holzapfel, lactobacilli fall into three groups in terms of their metabolic activities:
"Group A: Obligately homofermentative Lactobacilli"
"Group B: Facultatively heterofermentative Lactobacilli"
"Group C: Obligately heterofermentative Lactobacilli"
Each group has its own particular metabolic pathway and metabolizes certain types of energy sources/carbohydrates/sugars, which result in different lactic acid productions at certain range of temperatures. According to Wikipedia: "Group A LAB ferment hexoses [monosaccharides or simple sugars, each with six carbon atoms], producing lactic acid via the Embden–Meyerhof–Parnas (EMP) pathway. Group B LAB also ferment hexoses via the EMP pathway to produce lactic acid; additionally they may ferment pentoses [monosaccharides or simple sugars, each with five carbon atoms] via the phosphogluconate pathway producing lactic acid and acetic acid. Group C LAB ferment both hexoses and pentoses via the phosphogluconate pathway to produce lactate, ethanol, and CO2."
My point is that, we are dealing with a very complex issue that demands careful consideration. Within this particular context of the microflora ratio, I make the following suppositions
1. The ratio of wild yeast cells to bacteria cells that thrive in a sourdough culture can be modified by refreshing or repeated refreshings, techniques of refreshing, consistency of the refreshed culture, duration of cultivation of the culture, and controlling the temperature during the cultivation.
2. The pH of the culture has an impact on the yeast count and their fermentative activities therein. Disproportionately low acidic environment diminishes the leavening capability of the yeast cells within the culture. In other words, the yeast activity progressively slows down as the bacteria, which usually outnumber the yeasts, generate more and more organic acid beyond a certain threshold.
4. The degree of lacticity and leavening power of the starter culture will fundamentally determine the lacticity and leavening propensity of the pizza dough to which the culture is applied
3. For production of Neapolitan pizza dough, a proper equilibrium between the wild yeasts and bacteria needs to be procured in order to avoid producing unpleasantly sour and unsprung pizzas.
Considering the above-mentioned suppositions and in respect to your statement, "increasing the yeast count would alter the yeast:bacteria ratio", I believe the yeast:bacteria ratio is always naturally in a perpetual state of entropy or flux regardless
! Normally, the bacteria population—which are said to have substantial resistance to acidic environment—triumphs over the yeast population—which are said not to have as much resistance to acidic environment as their counterparts. Hence, I believe, this is one of the reasons that a culture needs to be refreshed periodically in order to reinstitute the ratio to a degree that is suitable toward the desired baked goods
. (Sometimes, I like to think of the lactic acid produced by the lactic acid bacteria as their natural defense mechanism
against micro-organisms, such as mold, that may try to invade their environment.)
In respect to your questions, "Would this [i.e., frothing the culture] really reduce the acid production unless the increased yeast activity allowed you to shorten the fermentation time?" and "Would you lose overall flavor if this is the case?", I make the assumption that aeration of the culture does not reduce the production of lactic acid, for I could still taste the lactic acid (sourness) in the dough with the same intensity as in a previous dough that was inoculated with the same culture, but not frothed. Even if frothing would effectuate a reduction of acid production (which I do not think is the case), it probably would not substantially impact the overall flavor, for the bacteria are ubiquitous (they reportedly outnumber the yeasts by a range between 100:1 and 1000:1) and I would allow a reasonably long fermentation duration, under right temperatures, to generate organic acids that add complexity and flavor to the dough. At this point, I am not primarily concerned with the number of bacteria; I am primarily concerned with the yeast cells and their leavening capacity. And, I do not desire to undermine the essential role of the bacteria. After all, the bacteria are said to be an integral and indispensable part of the equation or symbiosis.
Please, keep me posted in regard to the progress of your dough. Have a great weekend!