Dear Jordan, here is some information, however incomplete and erroneous, you asked for on dough zymology and enzymology. Inasmuch as exploration of dough fermentation, along with the indispensible chemical reactions of the participating enzymes, is an elaborate and complex subject (of which my understanding is narrow), I can only briefly touch on a few key aspects in a generalized manner. Yet, I hope this can serve you as a starting point in your explorations. I think that understanding the nature of wheat grains is a good place to start from. Based on some scientific and non-scientific literatures that I have studied, I make the following suppositions
, hopefully in a cohesive and logical order. ("Supposition" because I am not fully certain as to the truth value of my propositions below.)§1. Wheat Flour:
The three principal constituents of a kernel of wheat are:
, the sprouting component of the seed),
(See the 1st picture below.) Germ constitutes about 2.5% of weight of a wheat kernel, while endosperm constitutes about 83% and bran about 14.5% percent.§2. White Flour:
White flour, unlike whole-wheat flour, is commonly made from the wheat endosperm, which is composed of:
a. Complex and simple carbohydrates:
, AKA "complex carbohydrates", AKA "complex sugars", AKA "storage poly-saccharides" (about 68 to 76%)
or dietary fibers
, such as pentosans, (about 2 to 3%)
iii. Trace quantities of simpler sugars
, AKA "simple carbohydrates", AKA "mono-" or "di-saccharides" (less than 0.5%)
b. Gluten and non-gluten forming proteins
(about 6 to 18%)
, AKA oils
(about 1 to 1.5%)
(less than 0.6%), and
(11 to 14%)
For the nutritional parameters of Caputo Pizzeria '00' flour, which is the flour you currently use, see the 2nd picture below. For some of the rest of the Caputo flours, see the following links:
http://brickovenbaker.com/docs/pizzeriatech.pdf (Caputo '00' Pizzeria)
http://image.brickovenbaker.com/pdf/extratech.pdf (Caputo '00' Extra)
http://brickovenbaker.com/docs/rinforzatotech.pdf (Caputo '00' Rinforzato)
http://brickovenbaker.com/docs/pastatech.pdf (Caputo '00' Pasta Fresca e Gnocchi)
According to Paula Figoni (a food scientist and associate professor at the International Baking and Pastry Institute in the College of Culinary Arts at Jonson & Wales University in Providence, Rhode Island):
Starch makes up the bulk of flour (68–76 percent). . . . Starch is present in flour as small grains or granules. Some starch granules are damaged during the milling process or when flour is stored under damp conditions. When this happens, a very small amount of starch [i.e., poly-saccharide or complex carbo-hydrate] is broken down by amylase into sugars [i.e., simple carbo-hydrates] that are readily fermented by yeast. The amount of sugars naturally present in flour (less than 0.5 percent) is rarely high enough for proper yeast fermentation, which is why most yeast dough formulas include at least some sugar or a source of amylase.§3. Starch:
Chunks of protein (6–18 percent) act as the cement that holds starch granules in place in the endosperm. Together, glutenin and gliadin (i.e., the gluten-forming proteins) make up about 80 percent of the proteins in the endosperm. Other proteins in white flour include enzymes, such as amylase, protease, and lipase.
Moisture in flour typically ranges from 11–14 percent. When moisture content rises above 14 percent, flour is susceptible to fungus and mold growth, flavor changes, enzyme activity, and insect infestation. For these reasons, flour must be stored properly, covered and in a cool, dry place.
Other carbohydrates in flour besides starch include gums (2–3 percent), specifically pentosans. It is easy to overlook the importance of pentosan gums in white flour because they are present at relatively low levels. But they have at least one important function in flour. Because they typically absorb 10–15 times their weight in water, a small amount of pentosan gums makes a large contribution to the water absorption value of flour and to the consistency of batters and doughs. The small amounts present in wheat flour also appear to interact with gluten, improving its strength and structure. Pentosan gums are also a source of soluble dietary fiber.
Although only a small amount of lipids (1–1.5 percent)—oil and emulsifiers—are present in white flour, they are necessary for proper gluten development. Yet, because of its nature, wheat oil oxidizes easily and turns rancid, limiting the shelf life of flour. While not dangerous or unsafe, stale flour has a distinct cardboard flavor that is best avoided by storing flour properly and using it promptly.
Ash is composed of inorganic matter—mineral salts—naturally present in wheat kernels. It includes iron, copper, potassium, sodium, and zinc. Besides providing needed minerals to the diet, ash increases yeast fermentation by providing minerals to yeast. Ash has a gray color that carries over to the flour. If properly milled, however, white flour is relatively low in ash (less than 0.6 percent), because ash is concentrated in the bran layer, which is separated from the endosperm when white flour is milled. Ash is measured in flour and grain samples by burning the samples at very high temperatures—over 1000°F (538°C)—and weighing the remains.
Carotenoid pigments are present in white flour in extremely low amounts (1–4 parts per million). They provide the creamy, off-white color to unbleached flour. The carotenoid pigments in white flour are in the same family as beta-carotene, the orange pigment in carrots. (How Baking Works, 3rd Edition)
The starch content of wheat endosperm is encapsulated in the starch granules
. During germination of a wheat seed, the aleurone
(the membrane surrounding the endosperm) secretes, into the endosperm, alpha-amylase
enzyme which breaks down the endosperm starch into simple sugars in order to nurture the growing seedling. (See the 3rd picture below.)
This phenomenon seems to account for the trace amount of sugars naturally found in the endosperms of non-dormant wheat grains that are inevitably mixed with the sound, dormant grains to be milled into flour. During the milling process, some of the starch granules are inevitably fractured or smashed, which makes their inherent sugars readily available to be metabolized by the fermentative micro-organisms during dough fermentation. As to the unconverted starch, they need to wait to be dehydrated, hydrolyzed, enzyme-reacted, and broken down into simple sugars by the amylase enzymes (alpha & beta amylase) before they can be consumed and digested by the fermentative micro-organisms in dough.
Related to the phenomenon of germination is what is known as "sprouting damage". When it rains just before harvest and/or when damp conditions persist during the harvest, wheat grains may begin to germinate or sprout. The germination of wheat seed causes an increase in alpha-amylase, an enzyme that breaks down starch. Additionally, there is an increase in enzymes (such as protease
) that hydrolyze or break down the bonds that hold large protein molecules (such as the gluten
molecules in dough) together. Of the two, the starch-reducing enzyme has a greater impact on compromising the quality of flour and of products made therewith. The longer the grain sprouts, the greater will be the formation of the alpha-amylase enzyme.
According to Perten Instruments (an organization that specializes in quality control of grain, flour, and other products):
What is sprout damage? Under conditions of prolonged dampness or rain, grain kernels may start to germinate, or sprout, when the crop is still standing. Germination begins when kernels absorb water and generate enzymes that break down stored starch and protein in the endosperm. The enzymes release sugars from starch and amino acids from proteins which nourish the growing embryo.
Alpha-amylase is one of the enzymes produced in the sprouting kernel. Although some alpha-amylase enzyme is present in the embryo or germ of sound wheat kernels, when germination begins the embryo and layers surrounding the starchy endosperm produce the enzyme at an accelerating rate. A severely sprout-damaged kernel contains many thousands of times the amounts of enzyme present in kernels that are in the early stages of germination. Because of this, a wheat sample containing very low levels of severely sprouted kernels may exhibit significant amylase activity. Alpha-amylase converts starch into sugars in the sprouting kernel, and similarly breaks down the starch granules in wheat flour when mixed with water to make bread dough.
According to Wikipedia:
Sprout damage is undesirable germination of wheat kernels that occurs on mature, unharvested wheat when wet field conditions persist just prior to and during the harvest. Mature wheat that has been cut and left lying in the field prior to threshing is particularly vulnerable to sprout damage. Early cold weather in Canada often forces wheat producers there to cut and windrow their crop to allow for drying. Wet conditions can then cause widespread sprout damage. If it has occurred, there is a dramatic increase of the enzyme alpha-amylase. The Falling Number test is a measure of the presence of this enzyme. A high falling number indicates that the wheat is sound and satisfactory for most baking processes. A low falling number indicates that harmful sprouting has occurred and is suggestive of reduced baking quality. In bread, too much alpha-amylase activity will cause wet sticky bread crumb with large voids in the loaf, and too little [alpha-amylase activity] causes dry crumble bread crumb and high loaf density.
To see the distinctions between damaged and sound wheat kernels, see the 4th and 5th pictures below. Sprout damage can have significant ramifications on the performance of white flour in fermentation, baking, and end products—due to the fact that sprout damage causes generation of the alpha-amylase enzyme, excessive amount of which upsets the subtle balance of various enzymes in flour
Upon mixing water, salt, culture or fresh yeast, and flour together, the produced dough undergoes two principal enzymatic reactions:
a) Alpha-amylase breaks down the starch content of the flour into dextrins (a poly-saccharide that is soluble, thick, sticky, and gummy), and later
b) Beta-amylase breaks down the dextrins into maltose sugars (a di-saccharide). (Of course, later, the yeast cells consume and digest the maltose sugars in the process of fermentation, which causes generation of carbon dioxide gas inside dough, which consequently puffs up or rises as a result of the trapped gases.)
Hypothetically, if there is deficient amount of alpha-amylase in the dough, there won’t be sufficient amount of dextrin to be converted to maltose for the yeast cells to digest (cf. under-fermentation); hence, the pizza dough would poorly rise. On the other hand, hypothetically, if there is excessive alpha-amylase in the dough, it converts more starch into dextrin than can be converted to maltose by the beta-amylase (cf. over-fermentation). Subsequently, imbalance of the enzymes can cause disproportionate amount of unprocessed dextrin in the dough, which can lead to poor oven-spring and/or a chewy and gummy pizza crust (not excluding the crumb) beneath the sauce.
Pure starch, which is tasteless
, and insoluble in cold water, chemically consists of two types of molecules: amylose
(about 20-25%) and amylopectin
(about 75-80%). Both are comprised of several glucose
(i.e., simple sugar, C6
) units linked together by glycosides or glycosidic bonds. (The word "glucose" is a derivative of the Greek word glukus
, γλυκύς, meaning "sweet".) As "resistant starches", amylose and amylopectin are resistant to digestion
, and the former is more resistant than the latter. The amylopectin’s bond-branching takes place at 24 to 30 glucose units, which renders it as a soluble molecule that can be rapidly degraded as it has many end points for enzymes to attach themselves to. Unlike amylopectin, amylose contains fewer bond-branches, which cause it to be denser and to be hydrolyzed slower.
I think it is beneficial to have a rudimentary understanding of carbohydrates, as they are the fuel
for dough fermentation. I have formulated below a general, ad hoc
classification of carbo-hydrates, Cm
a. Complex Carbo-hydrates:
i. Oligo-saccharides* (meaning "few-sugars"):
a. Tri-, tetra-, penta-, hexa-, hepta-, octa-, nona-, & deca-saccharides ("saccharides" = simple sugars)
ii. Poly-saccharides* (meaning "many-sugars"):
a. Storage poly-saccharides (such as starch and dextrin)
b. Structure poly-saccharides (such as cellulose)
b. Simple Carbo-hydrates:
i. Mono-saccharides* (meaning "one-sugar", hence "simple sugars"), such as glucose (dextrose), fructose (levulose), galactose, xylose, and ribose
ii. Di-saccharides* (meaning "two-sugars"), such as maltose, sucrose, and lactose. (Some may deem simple carbo-hydrates exclusive of di-saccharides.)
*Mono-saccharides are the building blocks of di-saccharides, oligo-saccharides, and poly-saccharides. For example, both dextrine (a poly-saccharide, (C6
) and maltose (a di-saccharide, C12
) are respectively comprised of many units and two units of the simple sugar glucose (a mono-saccharide, C6
). The word “saccharide” is a derivative of the Latin word saccharum
, meaning "sugar".
As indicated above, various proteins are extant within the wheat endosperms, such as amylase enzyme (which breaks down starch to simple sugars), protease enzyme (which breaks down the bonds that hold gluten molecules together), glutenin (a gluten-forming protein, not an enzyme), gliadin (another gluten-forming protein, not an enzyme), and etc. Not every protein secreted to and/or generated in the wheat endosperm is an enzyme. Further, not every existing protein in white flour is a gluten-generating protein.§5. Enzymes:
Enzymes catalyze or substantially increase the rate of certain chemical reactions occurring in dough. In such enzymatic reactions, the complex molecules of starch and gluten (technically known as "substrates") are reduced to simpler molecules (technically known as "products"). Enzymes require a range of necessary
conditions—such as the proper pH levels, temperatures, specific substrate(s), and etc.—in order to properly carry out their functions. For instance, amylase and protease enzymes simplify their specific substrates, the specific molecules of starch and gluten respectively, under proper pH levels and temperatures. Note that salt acts as an enzyme inhibitor, meaning that it slows down the enzymatic reactions of the aforementioned enzymes. That is a principal reason for the absence of salt in the classic autolyse.
According to Wikipedia:
Enzymes catalyze chemical reactions involving the substrate(s). In the case of a single substrate, the substrate binds with the enzyme active site, and an enzyme-substrate complex is formed. The substrate is transformed into one or more products, which are then released from the active site. The active site is now free to accept another substrate molecule. (See the 6th picture below.)§6. Glutenin and Gliadin Proteins:
A viscous, sticky, and elastic substance is formed when glutenin and gliadin proteins of wheat flour are mixed with water. This substance is known as "gluten", which technically does not exist in the flour antecedent to hydration thereof. When the generated gluten in dough is appropriately kneaded, a gluten network forms throughout the dough which traps gases (i.e., carbon dioxide) produced during fermentation. As the gases are produced in volume, the gluten structure expands, causing the dough to rise or leaven
(derived from the Latin verb levare
, meaning "to lift" or "to levitate").§7. Amylase Enzymes:
Amylase catalyzes the simplification of the large endosperm starch molecules (poly-saccharides) into simpler and smaller sugar molecules, such as dextrin (a poly-saccharide with many units of glucose), maltose (a di-saccharide with two units of glucose), and later glucose (a mono-saccharide). The texture, digestibility, and flavors of these saccharides are generally proportionate to how much they have been broken down.
Therefore, a Caputo Pizzeria dough (composed only of water, salt, commercial yeast or culture, and flour) that had been subjected to 8 hours of fermentation is more likely to bear less favorable texture, digestibility, and flavor than the same dough that had been fermented for a longer period of time. As mentioned earlier, the timely and proper functionality of the enzymes necessarily require suitable pH levels, temperatures, and substrates.§8. Protease Enzyme:
Protease catalyzes the reduction of the large gluten molecules (hence the gluten structure) into simpler and smaller molecules that are more digestible to human stomach and intestine. (Lactic acid bacteria can also contribute to the protease activity in weakening the gluten and rendering it more extensible. lactobacillus bacteria produce enzymes that degrade gluten molecules.) The gluten breakdown by protease also generates amino acids that contribute to the browning (i.e., Millard browning) and flavor. (For "Millard browning", see http://en.wikipedia.org/wiki/Maillard_reaction
) Excessive protease activity can compromise the gluten structure and the leavening propensity of dough to the point of tearing or collapsing. The timely and proper functionality of protease necessarily involve befitting pH levels, temperatures, and substrates. The light texture, digestibility, and flavor of the pizza crust and cornicione are generally proportionate to the degree of breakdown of the gluten molecules.§9. Dough Maturation:
Within the above-constructed framework, "maturation"
of Neapolitan dough is significative of a point in time whereby the starch (i.e., complex carbo-hydrates) and protein (e.g., gluten) molecules of dough have been broken down—as a consequence of the enzymatic and fermentative processes—into simpler molecules, which contribute to the flavor, soft and fluffy texture, and digestion of the end product
. In this sense, maturation is an offspring
of the enzymatic and fermentative transformations.
If the Caputo Pizzeria flour, or another isotropic flour, is characterized with low amylase enzyme activity
(which I personally believe is the case with the Caputo Pizzeria flour), then a fermentation of short duration
may not give the amylase enzymes sufficient chance (without adding any enhancing additives) to timely and adequately de-synthesize the starch content of flour into dextrin and maltose in order to fuel fermentation, i.e., digestion of the simple sugars by the yeast cells. (Also, keep in mind that the enzymatic reactions of protease are symbiotically affected by the enzymatic reactions of amylase.) Theoretically, it does not matter how much fresh yeast or culture is poured in the dough, for it seems to me that dough maturation, to put it very briefly, is a result of (the reductive fermentation pathway):
1. Enough time and proper range of temperatures
for the starch to break down into simple sugars;
2. Enough time and proper range of temperatures
for the simple sugars to be digested by the fermentative micro-organisms into ethanol and carbon dioxide gas;
3. Enough time and proper range of temperatures
for the fermentative micro-organisms to generate an adequate level of lacticity (flavor), which contributes to weakening of the gluten molecular bonds;
4. Enough time and proper range of temperatures
for the gluten molecules to be simplified and, hence, the gluten structure to be physically palliated and relieved up to a point.Such simplicity—or molecular simplification—cultivates soft texture, digestibility, flavor, and elegance!
As a partial support for the claimed "low amylase enzyme activity" of the Caputo Pizzeria flour (which is reportedly milled by using gradual
grinding mechanisms in order to minimize breakage of starch granules), I quote Caputo’s officially reported falling number
: "340-360". In the flour industry, "falling number" is commonly used as a statistical likelihood of enzymatic activity of alpha-amylase in a wheat sample. It is a test that provides an indication of the amount of sprout damage that has occurred within a sample. Generally, a falling number value of 350 or above indicates low enzyme activity and sound wheat. As the amount of enzyme activity increases, the falling number decreases. Values below 200 indicate high levels of enzyme activity. A mill can certainly decrease the falling number of its flour by adding diastatic malt or fungal amylase in order to engineer and increase the level of enzymatic activity of its flour for the sake of a specific dough performance. For instance, the King Arthur Sir Lancelot flour is reportedly a malted flour, with a falling number value of 250 ± 30. The Caputo Pizzeria flour is said to be unmalted, with a falling number value, as quoted earlier, of 340–360.
Please, notice that in this post I have substantially neglected the indispensible roles of yeasts and bacteria (collectively, the engine
of fermentation), which produce their own vital enzymes in the process of fermenting dough. Have a great day!