Several years ago, when Marco (pizzanapoletana) was active on the forum, he said the fermenting the dough in bulk and then doing the division into individual dough balls was mandatory. Over the years, I got to the point where I could be a gadfly and write things intentionally in a way that Marco could not resist responding to. However, I could never get Marco to explain why the two-step process was necessary. I think the reason he did not elaborate on this matter was because at the time he was contemplating writing a book on the Neapolitan pizza style and he did not want to spill all of the beans on this forum, as I so noted in the second paragraph of Reply 63 at http://www.pizzamaking.com/forum/index.php/topic,14038.msg141218/topicseen.html#msg141218. However, from an explanation standpoint, I gave the matter my best shot at Reply 7 at http://www.pizzamaking.com/forum/index.php/topic,7022.msg60428.html#msg60428. You will also see Marco's attempt to defend the two-step process in response to scott r's comment, at Reply 54 at http://www.pizzamaking.com/forum/index.php/topic,2088.msg24291.html#msg24291.
Dear Peter, in my assessment, it is not easy to simply state why the "two-step process" (sometimes referred to as "double-rise") yields better results than the "one-step process"—because of the complexities
involved in this matter. Actual experimentation has fully substantiated, at least to many prominent bakers and pizzaioli, that the two-step process produces superior results indeed, yet they fall short to provide a rationale underlying the phenomenon. Perhaps, to know why, one needs to have a conceptual understanding of the system
, that is, the dough system
In my opinion, under the right conditions, the two-step process, as opposed to the one-step process, brings about:
1. Better dough maturation
(i.e., better balance between the physical attributes of dough extensibility
2. Better dough strength
(which is essentially another interrelated physical attribute of dough maturation), and
3. Better dough flavor
If I am not mistaken, Raymond Calvel also emphasized the importance of using double-rise for the sake of better dough maturation and flavor. However, I do not think he revealed any reasons. I naively believe the reasons lie in the yeast colonies (and their colonial behavior and patterns throughout the dough), yeast metabolism, and dough biochemistry. If I, as an amateur, were to account for all these here, it would probably take me several hours and about twenty pages. So, I will be absurdly brief, hoping that I can get my point across. There are many dots that need to be connected.
Basically, according to my ongoing studies, when the dough is manipulated, subdivided, and formed into dough balls after the first rise or first step, these very acts change the behavior of yeast colonies and the underlying physical structure of the dough
. These acts considerably impact the dough rheology, biochemistry, and metabolic behavior of Saccharomyces cerevisiae
as briefly outlined below:
1. Hydrolysis and enzymatic reduction of starch (amylose and amylopectin) to disaccharides, and reduction of proteins to smaller chains of amino acids;
2. Enzymatic reduction of disaccharides (maltose) to monosaccharides (glucose) in S. cerevisiae
3. S. cerevisiae
catabolic metabolism of glucose (including protein and lipid) molecules:
a. Aerobic cellular respiration (complete glucose oxidation/breakdown
1) Glycolysis (1 Glucose → 2 Pyruvate + 2 Water + 2 ATP + Heat)
2) Pyruvate decarboxylation (2 Pyruvate → 2 Acetyl-Coenzyme A + 2 Carbon Dioxide↑)
3) Citric acid cycle (2 Acetyl-Coenzyme A → 2 CoA-SH + 4 Carbon Dioxide↑ + 2 ATP + Heat)
4) Electron transport chain & chemiosmosis (CAC → 6 water + 32 ATP + Heat) Overall result of aerobic respiration: 1 Glucose + 6 Oxygen → 6 Water + 6 Carbon Dioxide↑ + 36 ATP + Heat
b. Anaerobic cellular respiration (incomplete glucose oxidation/breakdown
1) Glycolysis (1 Glucose → 2 Pyruvate + 2 Water + 2 ATP + Heat)
2) Alcoholic Fermentation (2 Pyruvate → 2 acetaldehyde + 2 Carbon Dioxide → 2 Ethanol) Overall result of anaerobic respiration: 1 Glucose → 2 Ethanol + 2 Carbon Dioxide)
4. S. cerevisiae
anabolic metabolism (which is contingent on aerobic respiration
1) Yeast division/reproduction
2) Yeast growth/biomass
As I mentioned above, the very acts of subdividing and forming dough balls change the behavior of yeast colonies and dough rheology. In the process, some metabolic waste materials (such as carbon dioxide and alcohol) are expelled, which has, to varying degrees, a revitalizing effect on the yeast cells. Most known biological organisms (including humans and S. cerevisiae
, which are homologous to human cells) can not sustain themselves too long in their own waste materials. To S. cerevisiae
, both carbon dioxide and ethanol (which is toxic) are waste products. The entrapment and accumulation of carbon dioxide in the dough gradually lowers the pH of the dough and, hence, the metabolic functions of the yeast cells. Moreover, the build-up of alcohol in the dough has the same effect on the yeast cells. S. cerevisiae
are acid intolerant. And, sufficient concentration of alcohol is lethal to the yeast cells. Dough manipulation, upon the conclusion of the first rise, will most likely relocate and/or disperse the yeast colonies from the acidification and alcoholization of their immediate surroundings. Keep in mind that, according to our present knowledge of S. cerevisiae
, the yeast cells are not motile
. They are not capable of self-motion.S. cerevisiae
are not able to ferment the fermentable substances of dough outside of their cells, nor can they proteolytically reduce the proteins (e.g., gluten) outside of their bodies. The yeast cells do not have the ability to secrete digestive enzymes into their surrounding environment; hence, they need to ingest the digestible disaccharides, hexoses, proteins, and lipids before they can act upon them. Therefore, the acts of subdividing and forming dough balls can shuffle the dough nutrients and redistribute the non-motile yeast cells for the sake of more uniform catabolic reactions in the dough. This is kind of similar to the "divide and conquer" principle.
The reintroduction of oxygen in the dough by manipulation may shift metabolism of S. cerevisiae
from anaerobic to aerobic or vice versa, and it may be accompanied by the Crabtree effect or Pasteur effect, depending on the levels of glucose and oxygen concentration. Fermentation (which yields no energy, ATP, of its own) is an incomplete
breakdown of glucose molecules, whereas aerobic cellular respiration (which yields about 36 ATPs per glucose molecule) is a complete
breakdown of glucose molecules. Hence, it might be advantageous to shift from anaerobic to aerobic respiration, which does no fermentation; nonetheless, it aids digestion, leavens the dough, and produces weak organic acids which contribute to flavor and bake quality. Naturally, it is all about the right balance between the aerobic and anaerobic reactions.
The yeast colonies behave much like highly organized multicellular entities or even armies. They are able to communicate and coordinate their behavior. Think about it, what happens if every yeast cell in the dough decides to carry out a different metabolic reaction or pathway, of which there are many:http://pathway.yeastgenome.org/SGD_biochemical_pwy_poster.pdf
The yeast cells appear to be much more sophisticated than once we thought. These single-celled eukaryotic organisms are sensitive and responsive to the changes in their environment (motion, pressure, pH, nutrient fluctuations, temperature, light, sound waves)
. According to the microbiology paper "How Saccharomyces
Responds to Nutrients" published in 2008 by the Department of Molecular Biology of Princeton University:
"Yeast cells sense the amount and quality of external nutrients through multiple interconnected signaling networks, which allow them to adjust their metabolism, transcriptional profile, and developmental program to adapt readily and appropriately to changing nutritional states. We present our current understanding of the nutritional sensing networks yeast cells rely on for perceiving the nutritional landscape, with particular emphasis on those sensitive to carbon and nitrogen sources. We describe the means by which these networks inform the cell's decision among the different developmental programs available to them—growth, quiescence, filamentous development, or meiosis/sporulation. We conclude that the highly interconnected signaling networks provide the cell with a highly nuanced view of the environment and that the cell can interpret that information through a sophisticated calculus to achieve optimum responses to any nutritional condition."
This is really a fascinating subject. Please, take everything I communicated above with a grain of salt as I am no professional microbiologist. Good night!
(The picture, below, shows yeast colonies expanding in a malt agar. Each colony is comprise of thousands to millions of yeast cells. In certain areas in the agar, there are individual expanding colonies built on top of one another.)