CHEMICAL PART OF DOUGH FORMATION
(BAKERY MANUAL. 1913)
All bread products are divided into three types: 1) simple bread 2) rich and 3) confectionery, according to which bread production is also being modified. The purpose of this guide is to focus on the production of plain bread.
Before considering all the operations of grain production, such as making dough, forming loaves, baking bread, etc. (the practical part of it), it is necessary to get acquainted with its theory, i.e., with chemical, physical and biological processes, occurring in the bread during these operations.
As already mentioned in the first part of this book, the dough, before being placed in the oven, is subjected to loosening after kneading, which can be done either by means of yeast or by chemical means, by means of baking powders, or finally by physical means by saturating the dough under pressure with carbon dioxide.With the chemical method (chemical) reaction occurs between the constituent parts of baking powders, flour does not participate in this process. Its loosening is accomplished exclusively by the physical action of the carbonic acid formed in statu nascendi.
The physical method consists exclusively of the physical action of carbon dioxide released under pressure from the dough, which is what it loosens. A completely different thing happens in the first method (the most common), which loosens by fermentation of yeast fungi. Very complex physicochemical and biological processes take place here, caused by the action of little yet studied microorganisms of semi-plant origin, the so-called yeast fungi, which are described in detail in the first part.
But in view of the importance of this process for baking, we will briefly review it again according to the latest investigations published only a few months ago (NOTE: this is in 1912)
During fermentation, carbonic acid is released, which is required by the baker to loosen the dough. The fermentation process is caused by yeasts, which are described in detail in the first part. Yeast fungus is a lower organism consisting of only one cell, about 0.01 millimeters in size. Pasteur considered the yeast fungus as an animal organism that has the ability to breathe, feed and multiply infinitely with such a rapidity that one yeast cell, under favorable conditions, can produce a million cells after 24 hours.
So from the action of the enzymes contained in the flour itself (diastase and cerealin), the starch, being sugared, turns into dextrin, which, together with gum, sugar and albumin, dissolves in the water contained in the dough. At the same time, the dissolved proteins turn into peptones, which impregnate the gluten, which, swelling, binds everything into a common mass.
Then the action of other enzymes contained in the yeast fungus (diastasis, cimaz, etc.) is removed, the decomposition of sugary substances into carbonic acid and alcohol begins (alcoholic fermentation). But since, in addition to (alcohol) yeast fungus, other fungi (from the air or sourdough) get into the dough, the chemical process is not limited to this, but oxidative reactions begin, in which alcohol, being oxidized, turns into acetic acid, sugar into lactic acid, starch in oil and the like.
The resulting acids, together with alcohol, act as a dissolving agent on gluten and pigment, which causes the dough to darken (in rye bread it reaches black).
Each yeast cell formed a colony of asco-spores. Thus, instead of individual cells, obtaining whole colonies of yeast fungi, he was able, by means of calculations, to determine the approximate amount of yeast fungi contained in the originally taken substance. Thus, he calculated that one gram of pressed yeast consumed by Parisian bakers contains from 5 to 6,000,000,000 live yeast cells. Further research showed that the dough after the end of fermentation contains only 5 to 600,000 of them. This amount of yeast grows rapidly in the old dough, which is why it is used in the form of a leaven that replaces the pressed yeast.
So, for example, studies have shown that in one gram of old dough after 4, 6 and 8 days, the number of cells reaches 200,000, 2,000,000 and 17 million. moreover, the yeast fungi increase due to starch. Indeed, after 24 hours in the old dough already from 0.7% to 1.9%, starch turns into sugar. But it must be borne in mind that for the benefit of the yeast fungi should not be allowed to ferment too vigorously, since in this case the yeast fungi quickly get tired and begin to multiply slowly. In addition, other bacteria that are harmful to them can easily develop.
The purpose of fermentation, as you know, is to produce carbon dioxide, which loosens the dough and makes it rise. - The amount of gas emitted, as studies have shown, depends not so much on the amount of yeast fungi, but on the amount of the Zymase enzyme formed, which they secrete, since the formation of sugar is the result of the action of this very diastasis. Etc. Linde found that one gram of yeast can produce 275 to 360 cc. sant. carbon dioxide depending on the amount of water (33% -45%) in the leaven. The more water the leaven contains, the more fermentation is.
Temperature also has a very large effect on their action: at + 20 ° C, the amount of carbon dioxide is released noticeably more than at 30 ° C. The same effect has the refreshing of the leaven, which promotes the release of this gas. Etc. Linde noted an interesting fact (based on his experiments) that the formation of the enzyme "Zymase" occurs inversely with the multiplication of cells, for example, the ability to produce diastasis is reduced in too rapidly multiplying yeasts.
Then he noticed that with the Viennese method of bread production, where yeast is put directly into the dough without preliminary preparation of the dough (raschin). yeast cells multiply the faster, the less they are in the leaven. In proportion to the content in the dough 1,2,4 or 8 thousand. yeast, each cell gives 8,6,3 or 2 generations in 18 hours. This curious phenomenon is probably explained by the harmful influence of the overcrowding of cells on their ability to reproduce. In practical terms, this has the meaning that the uneven distribution of yeast in the leaven is equalized to some extent by the greater or lesser ability of their cells to multiply.
The sourdough contains the same alcoholic fungus as in the pressed yeast, but somewhat smaller, and therefore it is called "saccharomyces minor", which releases carbonic acid without hydrogen. Other fungi also get into flour, for example, from sourdough, if it lies for a long time in a warm place, which do not form carbon dioxide at all, but cause exclusively acidic fermentation with their enzymes, converting starch into sugar, and sugar into lactic acid. The latter is eliminated by other bacteria that cause oil fermentation.
Therefore, it is very important for baking purposes that for loosening the dough, predominantly pressed yeast containing a pure culture of yeast fungus or, in extreme cases, fresh sourdough, but by no means sour, which can spoil the whole dough, is used.
It is not enough, after kneading the dough and adding loosening agents, to bake it, since this method will result in a very tasteless bread, consisting of a dense crumb with large voids inside. This is due to the fact that with this method, fermentation is often incomplete and not uniform, as a result of which those chemical processes that were described above do not end, and therefore some particles of flour remain unchanged.
As a result, practice has developed another method, where yeast or sourdough is not added immediately to the entire mass of the dough, but first only in a certain part of it, called raschin or dough, which is left alone for some time to give the dough time to come to the maximum state of fermentation. Then just add a fresh portion of flour and water to it. This fractional addition of flour and water to yeast or sourdough has the goal of, as it were, refreshing the yeast fungus, that is, at first giving it less work, and then, when it develops and grows stronger in a small amount of fresh dough, they give it new work, etc. until all the dough has been added. For the uniformity of the bread, after adding each new portion of flour, thoroughly mix the entire dough so that all its particles come into contact with the leaven, which contributes to a uniform and faster fermentation.
As mentioned in the first part of this book, pressed yeast or sourdough can be used to loosen the dough using yeast fungi. The former, containing an almost pure culture of the alcoholic fungus, develop mainly alcoholic fermentation (at least at the beginning of their action), and therefore give a non-acidic dough, which we usually use for white bread.
For black bread, which is usually baked sour or sweet-sour, sourdough is used, that is, an old fermented dough containing, in addition to alcoholic yeast, others that cause sour fermentation, as indicated above. But the leaven quickly deteriorates, and therefore it should be stored, especially in the summer, in a cool place (in the cellar), and its consistency should be in the form of a thick dough (it cannot be stored in a batter).
In the cold season, the leaven can also be stored in the baking room (for several days), but at the same time it is necessary to sprinkle it on top with dry flour and refresh it daily, that is, add to it while stirring fresh flour in the amount of 10% by weight of the leaven. It is common practice to leave about 10 lb. tsta on a sack of flour.
A good leaven is characterized by the following qualities: it has an alcoholic smell and a sour taste, it should not sink in water; when pressing its surface (with a finger), the formed depression should soon disappear. If baking is carried out continuously and part of the sourdough is constantly taken into work, then, as practice teaches, you should take no more than half of it each time, and immediately add the same amount of fresh dough (mixed in warm water), which, after mixing well, put in a warm place (at + 25 to 30 R.); here they let her stand quietly for two hours to allow the whole mass to ferment. If, on the contrary, the leaven is rarely used and it has to lie for several days (sometimes for weeks without using it, then, as indicated above, it must be refreshed by adding flour.
Some advise sprinkling it with table salt on top, which, on the one hand, delays fermentation, and on the other hand protects it from decay. To what extent the addition of salt (NaCl) delays fermentation, can be seen from the following (Intend. Journal of 1908, No. 5, Art. 85). According to T. Golden's research, an admixture of 16% table salt to the dough delays fermentation for 7 days, and 4% salt - for 14 hours.
If the leaven has deteriorated due to an oversight or due to the duration of storage, then it can be gradually corrected by constantly adding flour with sugar to it or by drying it, which is done as follows: small lumps are made from the spoiled leaven, which are placed in a dry place (Kudryavtsev's method). If there is no leaven left, and sour fermentation is required for black bread, then proceed as follows: Take 30 lbs. rye flour and pour in one bucket of warm water (at 31 R.). in which ¼ pound of compressed yeast is pre-diluted. Having mixed this dough well, let it stand quietly in a warm place (covering the bowl) for a day, and at first alcoholic fermentation is formed, which then turns into sour (like a leaven).
Having prepared the leaven in this way and passing the flour through a sieve to clean it from litter, they begin to prepare the raspin. For this, the required amount of yeast or sourdough is weighed out and stirred in warm (25 ° R.) water (cold water extremely inhibits fermentation), stirring well, especially when fermenting, in order to break all the lumps of dough into an even liquid gruel.
Then to the resulting liquid mass, first part of the flour (for rye bread, usually half of the flour) and water are added, and the dough is thoroughly mixed. After that, the mixed dough is sprinkled with flour on top and, covered with a lid, is placed in a warm place (at + 17 R.), where it is left alone for 6-8 hours so that the whole mass comes into fermentation.The end of the fermentation process is recognized by the bubbles and gas released on the surface of the dough, and the dough, which had almost doubled in volume by that time, begins to fall. Then add the rest of the flour with water to the rasschin in two or three steps, stirring well each time and letting the dough ferment for some time. The dough is considered sufficiently mixed when it does not stick to the fingers. After that, he is allowed to wander for another two hours, so that it rises again.
Many people recommend cooking raschin not with wheat or rye flour, but with potato flour, which presents the next big advantage. Potato flour contains some kind of, still insufficiently examined, nitrogenous substance (apparently an enzyme), which acts as a pathogen on yeast, as a result of which fermentation occurs much more vigorously and rather with a relatively smaller amount of yeast consumed. For this purpose, the potatoes are boiled (by putting steam in a vat with potatoes) and mixed with water to form a liquid gruel, to which, after cooling to + 25 or 30 C, yeast is added. When using potato rasch, the rest is done as usual (above).
It is necessary to pay attention so that fermentation does not last too long, otherwise, on the one hand, the dough will begin to taste too sour, and on the other, there is a risk that cracks will appear in the loaves through which carbon dioxide will escape, as a result of which the dough settles and the bread becomes dense. Therefore, at the moment when the dough finally rises, the loaf should be immediately put into the oven. But if this is not possible, then further fermentation must be stopped, for which it is enough to cool the loaves. For this purpose, they are transferred to a cool room or exposed to cool air.
The loaf, ready for baking, is a raw spongy mass consisting of elastic gluten mixed with starch particles and soaked in a solution of sugary substances and peptonized proteins. The pores of this loose mass are filled with bubbles of carbon dioxide, which keeps the dough from falling. An aqueous solution of this mass contains a small amount of alcohol, acetic and lactic acid, i.e., fermentation products. In this form, the loaves are loaded into the oven, where they undergo further chemical changes.
